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<span>Example</span> </div> </a> <button aria-controls="toc-Example-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Example subsection</span> </button> <ul id="toc-Example-sublist" class="vector-toc-list"> <li id="toc-Attempt_at_cryptanalysis" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Attempt_at_cryptanalysis"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>Attempt at cryptanalysis</span> </div> </a> <ul id="toc-Attempt_at_cryptanalysis-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Perfect_secrecy" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Perfect_secrecy"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Perfect secrecy</span> </div> </a> <ul id="toc-Perfect_secrecy-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Problems" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Problems"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Problems</span> </div> </a> <button aria-controls="toc-Problems-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Problems subsection</span> </button> <ul id="toc-Problems-sublist" class="vector-toc-list"> <li id="toc-True_randomness" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#True_randomness"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>True randomness</span> </div> </a> <ul id="toc-True_randomness-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Key_distribution" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Key_distribution"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Key distribution</span> </div> </a> <ul id="toc-Key_distribution-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Authentication" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Authentication"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.3</span> <span>Authentication</span> </div> </a> <ul id="toc-Authentication-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Common_implementation_errors" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Common_implementation_errors"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.4</span> <span>Common implementation errors</span> </div> </a> <ul id="toc-Common_implementation_errors-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Uses" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Uses"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Uses</span> </div> </a> <button aria-controls="toc-Uses-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Uses subsection</span> </button> <ul id="toc-Uses-sublist" class="vector-toc-list"> <li id="toc-Applicability" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Applicability"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Applicability</span> </div> </a> <ul id="toc-Applicability-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Quantum_and_post-quantum_cryptography" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Quantum_and_post-quantum_cryptography"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>Quantum and post-quantum cryptography</span> </div> </a> <ul id="toc-Quantum_and_post-quantum_cryptography-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Historical_uses" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Historical_uses"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.3</span> <span>Historical uses</span> </div> </a> <ul id="toc-Historical_uses-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-NSA" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#NSA"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.4</span> <span>NSA</span> </div> </a> <ul id="toc-NSA-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Exploits" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Exploits"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.5</span> <span>Exploits</span> </div> </a> <ul id="toc-Exploits-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">10</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">One-time pad</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 32 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-32" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">32 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%84%D9%88%D8%AD%D8%A9_%D8%A7%D9%84%D9%85%D8%B1%D8%A9_%D8%A7%D9%84%D9%88%D8%A7%D8%AD%D8%AF%D8%A9" title="لوحة المرة الواحدة – Arabic" lang="ar" hreflang="ar" data-title="لوحة المرة الواحدة" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/One-time_pad" title="One-time pad – Bosnian" lang="bs" hreflang="bs" data-title="One-time pad" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Bloc_d%27un_sol_%C3%BAs" title="Bloc d'un sol ús – Catalan" lang="ca" hreflang="ca" data-title="Bloc d'un sol ús" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Vernamova_%C5%A1ifra" title="Vernamova šifra – Czech" lang="cs" hreflang="cs" data-title="Vernamova šifra" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/One-time_pad" title="One-time pad – Danish" lang="da" hreflang="da" data-title="One-time pad" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/One-Time-Pad" title="One-Time-Pad – German" lang="de" hreflang="de" data-title="One-Time-Pad" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/%C3%9Chekordne_%C5%A1ifriplokk" title="Ühekordne šifriplokk – Estonian" lang="et" hreflang="et" data-title="Ühekordne šifriplokk" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%A3%CE%B7%CE%BC%CE%B5%CE%B9%CF%89%CE%BC%CE%B1%CF%84%CE%AC%CF%81%CE%B9%CE%BF_%CE%BC%CE%B9%CE%B1%CF%82_%CF%87%CF%81%CE%AE%CF%83%CE%B7%CF%82" title="Σημειωματάριο μιας χρήσης – Greek" lang="el" hreflang="el" data-title="Σημειωματάριο μιας χρήσης" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Libreta_de_un_solo_uso" title="Libreta de un solo uso – Spanish" lang="es" hreflang="es" data-title="Libreta de un solo uso" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%BE%D8%AF_%DB%8C%DA%A9%E2%80%8C%D8%A8%D8%A7%D8%B1_%D9%85%D8%B5%D8%B1%D9%81" title="پد یک‌بار مصرف – Persian" lang="fa" hreflang="fa" data-title="پد یک‌بار مصرف" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Masque_jetable" title="Masque jetable – French" lang="fr" hreflang="fr" data-title="Masque jetable" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%9B%90_%ED%83%80%EC%9E%84_%ED%8C%A8%EB%93%9C" title="원 타임 패드 – Korean" lang="ko" hreflang="ko" data-title="원 타임 패드" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Jednokratni_klju%C4%8D" title="Jednokratni ključ – Croatian" lang="hr" hreflang="hr" data-title="Jednokratni ključ" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Cifrario_di_Vernam" title="Cifrario di Vernam – Italian" lang="it" hreflang="it" data-title="Cifrario di Vernam" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A4%D7%A0%D7%A7%D7%A1_%D7%97%D7%93-%D7%A4%D7%A2%D7%9E%D7%99" title="פנקס חד-פעמי – Hebrew" lang="he" hreflang="he" data-title="פנקס חד-פעמי" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Vienkartinis_bloknotas" title="Vienkartinis bloknotas – Lithuanian" lang="lt" hreflang="lt" data-title="Vienkartinis bloknotas" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/Cifrari_del_Vernam" title="Cifrari del Vernam – Lombard" lang="lmo" hreflang="lmo" data-title="Cifrari del Vernam" data-language-autonym="Lombard" data-language-local-name="Lombard" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/One-time_pad" title="One-time pad – Dutch" lang="nl" hreflang="nl" data-title="One-time pad" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%AF%E3%83%B3%E3%82%BF%E3%82%A4%E3%83%A0%E3%83%91%E3%83%83%E3%83%89" title="ワンタイムパッド – Japanese" lang="ja" hreflang="ja" data-title="ワンタイムパッド" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Engangsn%C3%B8kkel" title="Engangsnøkkel – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Engangsnøkkel" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Eingongslykel" title="Eingongslykel – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Eingongslykel" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Szyfr_z_kluczem_jednorazowym" title="Szyfr z kluczem jednorazowym – Polish" lang="pl" hreflang="pl" data-title="Szyfr z kluczem jednorazowym" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/One-time_pad" title="One-time pad – Portuguese" lang="pt" hreflang="pt" data-title="One-time pad" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru badge-Q17559452 badge-recommendedarticle mw-list-item" title="recommended article"><a href="https://ru.wikipedia.org/wiki/%D0%A8%D0%B8%D1%84%D1%80_%D0%92%D0%B5%D1%80%D0%BD%D0%B0%D0%BC%D0%B0" title="Шифр Вернама – Russian" lang="ru" hreflang="ru" data-title="Шифр Вернама" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sq mw-list-item"><a href="https://sq.wikipedia.org/wiki/One-time_pad" title="One-time pad – Albanian" lang="sq" hreflang="sq" data-title="One-time pad" data-language-autonym="Shqip" data-language-local-name="Albanian" class="interlanguage-link-target"><span>Shqip</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/One-time_pad" title="One-time pad – Simple English" lang="en-simple" hreflang="en-simple" data-title="One-time pad" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/One-time_pad" title="One-time pad – Finnish" lang="fi" hreflang="fi" data-title="One-time pad" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Blankettchiffer" title="Blankettchiffer – Swedish" lang="sv" hreflang="sv" data-title="Blankettchiffer" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Tek_kullan%C4%B1ml%C4%B1k_%C5%9Fifre" title="Tek kullanımlık şifre – Turkish" lang="tr" hreflang="tr" data-title="Tek kullanımlık şifre" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk 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class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Encryption technique</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Not to be confused with <a href="/wiki/One-time_password" title="One-time password">One-time password</a>.</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">"One time code" redirects here. For the pre-arranged phrase, see <a href="/wiki/Code_(cryptography)#One-time_code" title="Code (cryptography)">Code (cryptography) § One-time code</a>.</div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-Lead_extra_info plainlinks metadata ambox ambox-style ambox-lead_extra_info" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/f/f2/Edit-clear.svg/40px-Edit-clear.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/f/f2/Edit-clear.svg/60px-Edit-clear.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/f/f2/Edit-clear.svg/80px-Edit-clear.svg.png 2x" data-file-width="48" data-file-height="48" /></span></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article's <b><a href="/wiki/Wikipedia:Manual_of_Style/Lead_section" title="Wikipedia:Manual of Style/Lead section">lead section</a> contains information that is not included elsewhere in the article</b>.<span class="hide-when-compact"> If the information is appropriate for the lead of the article, this information should also be included in the body of the article.</span> <span class="date-container"><i>(<span class="date">May 2023</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:NSA_DIANA_one_time_pad.tiff" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/19/NSA_DIANA_one_time_pad.tiff/lossless-page1-220px-NSA_DIANA_one_time_pad.tiff.png" decoding="async" width="220" height="195" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/19/NSA_DIANA_one_time_pad.tiff/lossless-page1-330px-NSA_DIANA_one_time_pad.tiff.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/19/NSA_DIANA_one_time_pad.tiff/lossless-page1-440px-NSA_DIANA_one_time_pad.tiff.png 2x" data-file-width="910" data-file-height="806" /></a><figcaption>A format of one-time pad used by the U.S. <a href="/wiki/National_Security_Agency" title="National Security Agency">National Security Agency</a>, code named DIANA. The table on the right is an aid for converting between plaintext and ciphertext using the characters at left as the key.</figcaption></figure> <p>In <a href="/wiki/Cryptography" title="Cryptography">cryptography</a>, the <b>one-time pad</b> (<b>OTP</b>) is an <a href="/wiki/Encryption" title="Encryption">encryption</a> technique that cannot be <a href="/wiki/Cryptanalysis" title="Cryptanalysis">cracked</a>, but requires the use of a single-use <a href="/wiki/Pre-shared_key" title="Pre-shared key">pre-shared key</a> that is larger than or equal to the size of the message being sent. In this technique, a <a href="/wiki/Plaintext" title="Plaintext">plaintext</a> is paired with a random secret <a href="/wiki/Key_(cryptography)" title="Key (cryptography)">key</a> (also referred to as a <i>one-time pad</i>). Then, each bit or character of the plaintext is encrypted by combining it with the corresponding bit or character from the pad using <a href="/wiki/Modular_arithmetic" title="Modular arithmetic">modular addition</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p><p>The resulting <a href="/wiki/Ciphertext" title="Ciphertext">ciphertext</a> will be impossible to decrypt or break if the following four conditions are met:<sup id="cite_ref-Numbers_Stations_2-0" class="reference"><a href="#cite_note-Numbers_Stations-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <ol><li>The key must be at least as long as the plaintext.</li> <li>The key must be <a href="/wiki/True_random" class="mw-redirect" title="True random">truly random</a>.</li> <li>The key must never be reused in whole or in part.</li> <li>The key must be kept completely secret by the communicating parties.</li></ol> <p>It has also been mathematically proven that any cipher with the property of perfect secrecy must use keys with effectively the same requirements as OTP keys.<sup id="cite_ref-shannon_4-0" class="reference"><a href="#cite_note-shannon-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Digital versions of one-time pad ciphers have been used by nations for critical <a href="/wiki/Diplomatic_communications" class="mw-redirect" title="Diplomatic communications">diplomatic</a> and <a href="/wiki/Military_communication" class="mw-redirect" title="Military communication">military communication</a>, but the problems of secure <a href="/wiki/Key_distribution" title="Key distribution">key distribution</a> make them impractical for most applications. </p><p>First described by <a href="/wiki/Frank_Miller_(cryptographer)" title="Frank Miller (cryptographer)">Frank Miller</a> in 1882,<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-BELLOVIN1_6-0" class="reference"><a href="#cite_note-BELLOVIN1-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> the one-time pad was re-invented in 1917. On July 22, 1919, U.S. Patent 1,310,719 was issued to <a href="/wiki/Gilbert_Vernam" title="Gilbert Vernam">Gilbert Vernam</a> for the <a href="/wiki/Exclusive_or" title="Exclusive or">XOR</a> operation used for the encryption of a one-time pad.<sup id="cite_ref-Google_7-0" class="reference"><a href="#cite_note-Google-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Derived from his <i>Vernam cipher</i>, the system was a cipher that combined a message with a key read from a <a href="/wiki/Punched_tape" title="Punched tape">punched tape</a>. In its original form, Vernam's system was vulnerable because the key tape was a loop, which was reused whenever the loop made a full cycle. One-time use came later, when <a href="/wiki/Joseph_Mauborgne" title="Joseph Mauborgne">Joseph Mauborgne</a> recognized that if the key tape were totally random, then <a href="/wiki/Cryptanalysis" title="Cryptanalysis">cryptanalysis</a> would be impossible.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p><p>The "pad" part of the name comes from early implementations where the key material was distributed as a pad of paper, allowing the current top sheet to be torn off and destroyed after use. For concealment the pad was sometimes so small that a powerful <a href="/wiki/Loupe" title="Loupe">magnifying glass</a> was required to use it. The <a href="/wiki/KGB" title="KGB">KGB</a> used pads of such size that they could fit in the palm of a hand,<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> or in a <a href="/wiki/Walnut" title="Walnut">walnut</a> shell.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> To increase security, one-time pads were sometimes printed onto sheets of highly flammable <a href="/wiki/Nitrocellulose" title="Nitrocellulose">nitrocellulose</a>, so that they could easily be burned after use. </p><p>There is some ambiguity to the term "Vernam cipher" because some sources use "Vernam cipher" and "one-time pad" synonymously, while others refer to any additive <a href="/wiki/Stream_cipher" title="Stream cipher">stream cipher</a> as a "Vernam cipher", including those based on a <a href="/wiki/Cryptographically_secure_pseudorandom_number_generator" title="Cryptographically secure pseudorandom number generator">cryptographically secure pseudorandom number generator</a> (CSPRNG).<sup id="cite_ref-kahn_11-0" class="reference"><a href="#cite_note-kahn-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Frank_Miller_(cryptography)" class="mw-redirect" title="Frank Miller (cryptography)">Frank Miller</a> in 1882 was the first to describe the one-time pad system for securing telegraphy.<sup id="cite_ref-BELLOVIN1_6-1" class="reference"><a href="#cite_note-BELLOVIN1-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-bio_12-0" class="reference"><a href="#cite_note-bio-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p><p>The next one-time pad system was electrical. In 1917, <a href="/wiki/Gilbert_Vernam" title="Gilbert Vernam">Gilbert Vernam</a> (of <a href="/wiki/AT%26T_Corporation" title="AT&T Corporation">AT&T Corporation</a>) invented<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> and later patented in 1919 (<span><a rel="nofollow" class="external text" href="https://patents.google.com/patent/US1310719">U.S. patent 1,310,719</a></span>) a cipher based on <a href="/wiki/Teleprinter" title="Teleprinter">teleprinter</a> technology. Each character in a message was electrically combined with a character on a <a href="/wiki/Punched_tape" title="Punched tape">punched paper tape</a> key. <a href="/wiki/Joseph_Mauborgne" title="Joseph Mauborgne">Joseph Mauborgne</a> (then a <a href="/wiki/Captain_(U.S._Army)" class="mw-redirect" title="Captain (U.S. Army)">captain</a> in the <a href="/wiki/U.S._Army" class="mw-redirect" title="U.S. Army">U.S. Army</a> and later chief of the <a href="/wiki/Signal_Corps_(United_States_Army)" class="mw-redirect" title="Signal Corps (United States Army)">Signal Corps</a>) recognized that the character sequence on the key tape could be completely random and that, if so, cryptanalysis would be more difficult. Together they invented the first one-time tape system.<sup id="cite_ref-kahn_11-1" class="reference"><a href="#cite_note-kahn-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p><p>The next development was the paper pad system. Diplomats had long used codes and ciphers for confidentiality and to minimize <a href="/wiki/Telegraphy" title="Telegraphy">telegraph</a> costs. For the codes, words and phrases were converted to groups of numbers (typically 4 or 5 digits) using a dictionary-like <a href="/wiki/Codebook" title="Codebook">codebook</a>. For added security, secret numbers could be combined with (usually modular addition) each code group before transmission, with the secret numbers being changed periodically (this was called <a href="/wiki/Superencryption" class="mw-redirect" title="Superencryption">superencryption</a>). In the early 1920s, three German cryptographers (Werner Kunze, Rudolf Schauffler, and Erich Langlotz), who were involved in breaking such systems, realized that they could never be broken if a separate randomly chosen additive number was used for every code group. They had duplicate paper pads printed with lines of random number groups. Each page had a serial number and eight lines. Each line had six 5-digit numbers. A page would be used as a work sheet to encode a message and then destroyed. The <a href="/wiki/Serial_number" title="Serial number">serial number</a> of the page would be sent with the encoded message. The recipient would reverse the procedure and then destroy his copy of the page. The German foreign office put this system into operation by 1923.<sup id="cite_ref-kahn_11-2" class="reference"><a href="#cite_note-kahn-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p><p>A separate notion was the use of a one-time pad of letters to encode plaintext directly as in the example below. <a href="/wiki/Leo_Marks" title="Leo Marks">Leo Marks</a> describes inventing such a system for the British <a href="/wiki/Special_Operations_Executive" title="Special Operations Executive">Special Operations Executive</a> during <a href="/wiki/World_War_II" title="World War II">World War II</a>, though he suspected at the time that it was already known in the highly compartmentalized world of cryptography, as for instance at <a href="/wiki/Bletchley_Park" title="Bletchley Park">Bletchley Park</a>.<sup id="cite_ref-marks_14-0" class="reference"><a href="#cite_note-marks-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p><p>The final discovery was made by information theorist <a href="/wiki/Claude_Shannon" title="Claude Shannon">Claude Shannon</a> in the 1940s who recognized and proved the theoretical significance of the one-time pad system. Shannon delivered his results in a classified report in 1945 and published them openly in 1949.<sup id="cite_ref-shannon_4-1" class="reference"><a href="#cite_note-shannon-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> At the same time, Soviet information theorist <a href="/wiki/Vladimir_Kotelnikov" title="Vladimir Kotelnikov">Vladimir Kotelnikov</a> had independently proved the absolute security of the one-time pad; his results were delivered in 1941 in a report that apparently remains classified.<sup id="cite_ref-kotelnikov_15-0" class="reference"><a href="#cite_note-kotelnikov-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> </p><p>There also exists a quantum analogue of the one time pad, which can be used to exchange <a href="/wiki/Quantum_state" title="Quantum state">quantum states</a> along a one-way <a href="/wiki/Quantum_channel" title="Quantum channel">quantum channel</a> with perfect secrecy, which is sometimes used in quantum computing. It can be shown that a shared secret of at least 2n classical bits is required to exchange an n-qubit quantum state along a one-way quantum channel (by analogue with the result that a key of n bits is required to exchange an n bit message with perfect secrecy). A scheme proposed in 2000 achieves this bound. One way to implement this quantum one-time pad is by dividing the 2n bit key into n pairs of bits. To encrypt the state, for each pair of bits i in the key, one would apply an X gate to qubit i of the state if and only if the first bit of the pair is 1, and apply a Z gate to qubit i of the state if and only if the second bit of the pair is 1. Decryption involves applying this transformation again, since X and Z are their own inverses. This can be shown to be perfectly secret in a quantum setting.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Example">Example</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=2" title="Edit section: Example"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Suppose <a href="/wiki/Alice_and_Bob" title="Alice and Bob">Alice</a> wishes to send the message <code>hello</code> to <a href="/wiki/Alice_and_Bob" title="Alice and Bob">Bob</a>. Assume two pads of paper containing identical random sequences of letters were somehow previously produced and securely issued to both. Alice chooses the appropriate unused page from the pad. The way to do this is normally arranged for in advance, as for instance "use the 12th sheet on 1 May", or "use the next available sheet for the next message". </p><p>The material on the selected sheet is the <i>key</i> for this message. Each letter from the pad will be combined in a predetermined way with one letter of the message. (It is common, but not required, to <a href="/wiki/Character_encoding" title="Character encoding">assign each letter a numerical value</a>, e.g., <code>a</code> is 0, <code>b</code> is 1, and so on.) </p><p>In this example, the technique is to combine the key and the message using <a href="/wiki/Modular_arithmetic" title="Modular arithmetic">modular addition</a>, not unlike the <a href="/wiki/Vigen%C3%A8re_cipher" title="Vigenère cipher">Vigenère cipher</a>. The numerical values of corresponding message and key letters are added together, modulo 26. So, if key material begins with <code>XMCKL</code> and the message is <code>hello</code>, then the coding would be done as follows: </p> <pre> h e l l o message 7 (h) 4 (e) 11 (l) 11 (l) 14 (o) message + 23 (X) 12 (M) 2 (C) 10 (K) 11 (L) key = 30 16 13 21 25 message + key = 4 (E) 16 (Q) 13 (N) 21 (V) 25 (Z) (message + key) mod 26 E Q N V Z → ciphertext </pre> <p>If a number is larger than 25, then the remainder after subtraction of 26 is taken in modular arithmetic fashion. This simply means that if the computations "go past" Z, the sequence starts again at A. </p><p>The ciphertext to be sent to Bob is thus <code>EQNVZ</code>. Bob uses the matching key page and the same process, but in reverse, to obtain the <a href="/wiki/Plaintext" title="Plaintext">plaintext</a>. Here the key is <i>subtracted</i> from the ciphertext, again using modular arithmetic: </p> <pre> E Q N V Z ciphertext 4 (E) 16 (Q) 13 (N) 21 (V) 25 (Z) ciphertext − 23 (X) 12 (M) 2 (C) 10 (K) 11 (L) key = −19 4 11 11 14 ciphertext – key = 7 (h) 4 (e) 11 (l) 11 (l) 14 (o) ciphertext – key (mod 26) h e l l o → message </pre> <p>Similar to the above, if a number is negative, then 26 is added to make the number zero or higher. </p><p>Thus Bob recovers Alice's plaintext, the message <code>hello</code>. Both Alice and Bob destroy the key sheet immediately after use, thus preventing reuse and an attack against the cipher. The <a href="/wiki/KGB" title="KGB">KGB</a> often issued its <a href="/wiki/Espionage" title="Espionage">agents</a> one-time pads printed on tiny sheets of flash paper, paper chemically converted to <a href="/wiki/Nitrocellulose" title="Nitrocellulose">nitrocellulose</a>, which burns almost instantly and leaves no ash.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> </p><p>The classical one-time pad of espionage used actual pads of minuscule, easily concealed paper, a sharp pencil, and some <a href="/wiki/Mental_arithmetic" class="mw-redirect" title="Mental arithmetic">mental arithmetic</a>. The method can be implemented now as a software program, using data files as input (plaintext), output (ciphertext) and key material (the required random sequence). The <a href="/wiki/Exclusive_or" title="Exclusive or">exclusive or</a> (XOR) operation is often used to combine the plaintext and the key elements, and is especially attractive on computers since it is usually a native machine instruction and is therefore very fast. It is, however, difficult to ensure that the key material is actually random, is used only once, never becomes known to the opposition, and is completely destroyed after use. The auxiliary parts of a software one-time pad implementation present real challenges: secure handling/transmission of plaintext, truly random keys, and one-time-only use of the key. </p> <div class="mw-heading mw-heading3"><h3 id="Attempt_at_cryptanalysis">Attempt at cryptanalysis</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=3" title="Edit section: Attempt at cryptanalysis"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>To continue the example from above, suppose Eve intercepts Alice's ciphertext: <code>EQNVZ</code>. If Eve tried every possible key, she would find that the key <code>XMCKL</code> would produce the plaintext <code>hello</code>, but she would also find that the key <code>TQURI</code> would produce the plaintext <code>later</code>, an equally plausible message: </p> <pre> 4 (E) 16 (Q) 13 (N) 21 (V) 25 (Z) ciphertext − 19 (T) 16 (Q) 20 (U) 17 (R) 8 (I) possible key = −15 0 −7 4 17 ciphertext-key = 11 (l) 0 (a) 19 (t) 4 (e) 17 (r) ciphertext-key (mod 26) </pre> <p>In fact, it is possible to "decrypt" out of the ciphertext any message whatsoever with the same number of characters, simply by using a different key, and there is no information in the ciphertext that will allow Eve to choose among the various possible readings of the ciphertext.<sup id="cite_ref-schneierotp_18-0" class="reference"><a href="#cite_note-schneierotp-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> </p><p>If the key is not truly random, it is possible to use statistical analysis to determine which of the plausible keys is the "least" random and therefore more likely to be the correct one. If a key is reused, it will noticeably be the only key that produces sensible plaintexts from both ciphertexts (the chances of some random <i>incorrect</i> key also producing two sensible plaintexts are very slim). </p> <div class="mw-heading mw-heading2"><h2 id="Perfect_secrecy">Perfect secrecy</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=4" title="Edit section: Perfect secrecy"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>One-time pads are "<a href="/wiki/Information-theoretic_security" title="Information-theoretic security">information-theoretically secure</a>" in that the encrypted message (i.e., the <a href="/wiki/Ciphertext" title="Ciphertext">ciphertext</a>) provides no information about the original message to a <a href="/wiki/Cryptanalyst" class="mw-redirect" title="Cryptanalyst">cryptanalyst</a> (except the maximum possible length<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>note 1<span class="cite-bracket">]</span></a></sup> of the message). This is a very strong notion of security first developed during WWII by <a href="/wiki/Claude_Shannon" title="Claude Shannon">Claude Shannon</a> and proved, mathematically, to be true for the one-time pad by Shannon at about the same time. His result was published in the <i>Bell System Technical Journal</i> in 1949.<sup id="cite_ref-Shannon_20-0" class="reference"><a href="#cite_note-Shannon-20"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> If properly used, one-time pads are secure in this sense even against adversaries with infinite computational power. </p><p>Shannon proved, using <a href="/wiki/Information_theory" title="Information theory">information theoretic</a> considerations, that the one-time pad has a property he termed <i>perfect secrecy</i>; that is, the ciphertext <i>C</i> gives absolutely no additional <a href="/wiki/Information" title="Information">information</a> about the <a href="/wiki/Plaintext" title="Plaintext">plaintext</a>.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>note 2<span class="cite-bracket">]</span></a></sup> This is because (intuitively), given a truly uniformly random key that is used only once, a ciphertext can be translated into <i>any</i> plaintext of the same length, and all are equally likely. Thus, the <i><a href="/wiki/A_priori_(philosophy)" class="mw-redirect" title="A priori (philosophy)">a priori</a></i> probability of a plaintext message <i>M</i> is the same as the <i><a href="/wiki/Empirical_knowledge" class="mw-redirect" title="Empirical knowledge">a posteriori</a></i> probability of a plaintext message <i>M</i> given the corresponding ciphertext. </p><p>Conventional <a href="/wiki/Symmetric_encryption" class="mw-redirect" title="Symmetric encryption">symmetric encryption algorithms</a> use complex patterns of <a href="/wiki/Substitution_cipher" title="Substitution cipher">substitution</a> and <a href="/wiki/Transposition_cipher" title="Transposition cipher">transpositions</a>. For the best of these currently in use, it is not known whether there can be a cryptanalytic procedure that can efficiently reverse (or even <a href="/wiki/Partial_inverse" class="mw-redirect" title="Partial inverse">partially reverse</a>) these transformations without knowing the key used during encryption. Asymmetric encryption algorithms depend on mathematical problems that are <a href="/wiki/Super-polynomial_time" class="mw-redirect" title="Super-polynomial time">thought to be difficult</a> to solve, such as <a href="/wiki/Integer_factorization" title="Integer factorization">integer factorization</a> or the <a href="/wiki/Discrete_logarithm" title="Discrete logarithm">discrete logarithm</a>. However, there is no proof that these problems are hard, and a mathematical breakthrough could make existing systems vulnerable to attack.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>note 3<span class="cite-bracket">]</span></a></sup> </p><p>Given perfect secrecy, in contrast to conventional symmetric encryption, the one-time pad is immune even to brute-force attacks. Trying all keys simply yields all plaintexts, all equally likely to be the actual plaintext. Even with a partially known plaintext, brute-force attacks cannot be used, since an attacker is unable to gain any information about the parts of the key needed to decrypt the rest of the message. The parts of the plaintext that are known will reveal <i>only</i> the parts of the key corresponding to them, and they correspond on a <a href="/wiki/Bijection" title="Bijection">strictly one-to-one basis</a>; a uniformly random key's bits will be <a href="/wiki/Independence_(probability_theory)" title="Independence (probability theory)">independent</a>. </p><p><a href="/wiki/Quantum_cryptography" title="Quantum cryptography">Quantum cryptography</a> and <a href="/wiki/Post-quantum_cryptography" title="Post-quantum cryptography">post-quantum cryptography</a> involve studying the impact of quantum computers on <a href="/wiki/Information_security" title="Information security">information security</a>. <a href="/wiki/Quantum_computing" title="Quantum computing">Quantum computers</a> have been shown by <a href="/wiki/Shor%27s_algorithm" title="Shor's algorithm">Peter Shor</a> and others to be much faster at solving some problems that the security of traditional asymmetric encryption algorithms depends on. The cryptographic algorithms that depend on these problems' difficulty would be rendered obsolete with a powerful enough quantum computer. One-time pads, however, would remain secure, as perfect secrecy does not depend on assumptions about the computational resources of an attacker. </p> <div class="mw-heading mw-heading2"><h2 id="Problems">Problems</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=5" title="Edit section: Problems"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Despite Shannon's proof of its security, the one-time pad has serious drawbacks in practice because it requires: </p> <ul><li>Truly random, as opposed to <a href="/wiki/Pseudorandomness" title="Pseudorandomness"><i>pseudorandom</i></a>, one-time pad values, which is a non-trivial requirement. <a href="/wiki/Random_number_generation" title="Random number generation">Random number generation</a> in computers is often difficult, and <a href="/wiki/Pseudorandom_number_generator" title="Pseudorandom number generator">pseudorandom number generators</a> are often used for their speed and usefulness for most applications. <a href="/wiki/True_random_number_generator" class="mw-redirect" title="True random number generator">True random number generators</a> exist, but are typically slower and more specialized.</li> <li>Secure generation and exchange of the one-time pad values, which must be at least as long as the message. This is important because the security of the one-time pad depends on the security of the one-time pad exchange. If an attacker is able to intercept the one-time pad value, they can decrypt messages sent using the one-time pad.<sup id="cite_ref-schneierotp_18-1" class="reference"><a href="#cite_note-schneierotp-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup></li> <li>Careful treatment to make sure that the one-time pad values continue to remain secret and are disposed of correctly, preventing any reuse (partially or entirely)—hence "one-time". Problems with <a href="/wiki/Data_remanence" title="Data remanence">data remanence</a> can make it difficult to completely erase computer media.</li></ul> <p>One-time pads solve few current practical problems in cryptography. High-quality <a href="/wiki/Cipher" title="Cipher">ciphers</a> are widely available and their security is not currently considered a major worry.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> Such ciphers are almost always easier to employ than one-time pads because the amount of key material that must be properly and securely generated, distributed and stored is far smaller.<sup id="cite_ref-schneierotp_18-2" class="reference"><a href="#cite_note-schneierotp-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> Additionally, <a href="/wiki/Public_key_cryptography" class="mw-redirect" title="Public key cryptography">public key cryptography</a> overcomes the problem of key distribution. </p> <div class="mw-heading mw-heading3"><h3 id="True_randomness">True randomness</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=6" title="Edit section: True randomness"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>High-quality random numbers are difficult to generate. The random number generation functions in most <a href="/wiki/Programming_language" title="Programming language">programming language</a> libraries are not suitable for cryptographic use. Even those generators that are suitable for normal cryptographic use, including <a href="/wiki//dev/random" title="/dev/random">/dev/random</a> and many <a href="/wiki/Hardware_random_number_generator" title="Hardware random number generator">hardware random number generators</a>, may make some use of cryptographic functions whose security has not been proven. An example of a technique for generating pure randomness is measuring <a href="/wiki/Radioactive_decay" title="Radioactive decay">radioactive emissions</a>.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> </p><p>In particular, one-time use is absolutely necessary. For example, if <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p_{1}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle p_{1}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b9b58f22283ca46dd5da309cc34303b06a797783" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; margin-left: -0.089ex; width:2.313ex; height:2.009ex;" alt="{\displaystyle p_{1}}"></span> and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p_{2}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle p_{2}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/43f1b08d7d69712872e051c2b33fdfa9f5d42319" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; margin-left: -0.089ex; width:2.313ex; height:2.009ex;" alt="{\displaystyle p_{2}}"></span> represent two distinct plaintext messages and they are each encrypted by a common key <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle k}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>k</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle k}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c3c9a2c7b599b37105512c5d570edc034056dd40" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.211ex; height:2.176ex;" alt="{\displaystyle k}"></span>, then the respective ciphertexts are given by: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle c_{1}=p_{1}\oplus k}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>c</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mo>=</mo> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mo>⊕</mo> <mi>k</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle c_{1}=p_{1}\oplus k}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ff9b8f1e11968e11bb13fae563ea5113ca1578b8" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:11.435ex; height:2.509ex;" alt="{\displaystyle c_{1}=p_{1}\oplus k}"></span></dd> <dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle c_{2}=p_{2}\oplus k}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>c</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> <mo>=</mo> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> <mo>⊕</mo> <mi>k</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle c_{2}=p_{2}\oplus k}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/9e87e7aba43cfbd3b30ce4fe095d22902f0ebb72" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:11.435ex; height:2.509ex;" alt="{\displaystyle c_{2}=p_{2}\oplus k}"></span></dd></dl> <p>where <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \oplus }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo>⊕</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \oplus }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8b16e2bdaefee9eed86d866e6eba3ac47c710f60" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.505ex; width:1.808ex; height:2.176ex;" alt="{\displaystyle \oplus }"></span> means <a href="/wiki/XOR" class="mw-redirect" title="XOR">XOR</a>. If an attacker were to have both ciphertexts <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle c_{1}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>c</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle c_{1}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/77b7dc6d279091d354e0b90889b463bfa7eb7247" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.061ex; height:2.009ex;" alt="{\displaystyle c_{1}}"></span> and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle c_{2}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>c</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle c_{2}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/0b30ba1b247fb8d334580cec68561e749d24aff2" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.061ex; height:2.009ex;" alt="{\displaystyle c_{2}}"></span>, then simply taking the <a href="/wiki/XOR" class="mw-redirect" title="XOR">XOR</a> of <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle c_{1}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>c</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle c_{1}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/77b7dc6d279091d354e0b90889b463bfa7eb7247" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.061ex; height:2.009ex;" alt="{\displaystyle c_{1}}"></span> and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle c_{2}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>c</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle c_{2}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/0b30ba1b247fb8d334580cec68561e749d24aff2" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.061ex; height:2.009ex;" alt="{\displaystyle c_{2}}"></span> yields the <a href="/wiki/XOR" class="mw-redirect" title="XOR">XOR</a> of the two plaintexts <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p_{1}\oplus p_{2}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mo>⊕</mo> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle p_{1}\oplus p_{2}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e382d188c40aa2a05bf74599ef75e1b7ab5f0625" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; margin-left: -0.089ex; width:7.377ex; height:2.343ex;" alt="{\displaystyle p_{1}\oplus p_{2}}"></span>. (This is because taking the <a href="/wiki/XOR" class="mw-redirect" title="XOR">XOR</a> of the common key <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle k}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>k</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle k}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c3c9a2c7b599b37105512c5d570edc034056dd40" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.211ex; height:2.176ex;" alt="{\displaystyle k}"></span> with itself yields a constant bitstream of zeros.) <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p_{1}\oplus p_{2}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mo>⊕</mo> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle p_{1}\oplus p_{2}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e382d188c40aa2a05bf74599ef75e1b7ab5f0625" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; margin-left: -0.089ex; width:7.377ex; height:2.343ex;" alt="{\displaystyle p_{1}\oplus p_{2}}"></span> is then the equivalent of a running key cipher.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2023)">citation needed</span></a></i>]</sup> </p><p>If both plaintexts are in a <a href="/wiki/Natural_language" title="Natural language">natural language</a> (e.g., English or Russian), each stands a very high chance of being recovered by <a href="/wiki/Heuristic" title="Heuristic">heuristic</a> cryptanalysis, with possibly a few ambiguities. Of course, a longer message can only be broken for the portion that overlaps a shorter message, plus perhaps a little more by completing a word or phrase. The most famous exploit of this vulnerability occurred with the <a href="/wiki/Venona_project" title="Venona project">Venona project</a>.<sup id="cite_ref-nsa_25-0" class="reference"><a href="#cite_note-nsa-25"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Key_distribution">Key distribution</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=7" title="Edit section: Key distribution"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Key_distribution" title="Key distribution">Key distribution</a></div> <p>Because the pad, like all <a href="/wiki/Shared_secret" title="Shared secret">shared secrets</a>, must be passed and kept secure, and the pad has to be at least as long as the message, there is often no point in using a one-time pad, as one can simply send the plain text instead of the pad (as both can be the same size and have to be sent securely).<sup id="cite_ref-schneierotp_18-3" class="reference"><a href="#cite_note-schneierotp-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> However, once a very long pad has been securely sent (e.g., a computer disk full of random data), it can be used for numerous future messages, until the sum of the messages' sizes equals the size of the pad. <a href="/wiki/Quantum_key_distribution" title="Quantum key distribution">Quantum key distribution</a> also proposes a solution to this problem, assuming <a href="/wiki/Fault_tolerance" title="Fault tolerance">fault-tolerant</a> quantum computers. </p><p>Distributing very long one-time pad keys is inconvenient and usually poses a significant security risk.<sup id="cite_ref-Numbers_Stations_2-1" class="reference"><a href="#cite_note-Numbers_Stations-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The pad is essentially the encryption key, but unlike keys for modern ciphers, it must be extremely long and is far too difficult for humans to remember. Storage media such as <a href="/wiki/Thumb_drive" class="mw-redirect" title="Thumb drive">thumb drives</a>, <a href="/wiki/DVD-R" class="mw-redirect" title="DVD-R">DVD-Rs</a> or personal <a href="/wiki/Digital_audio_player" class="mw-redirect" title="Digital audio player">digital audio players</a> can be used to carry a very large one-time-pad from place to place in a non-suspicious way, but the need to transport the pad physically is a burden compared to the key negotiation protocols of a modern public-key cryptosystem. Such media cannot reliably be erased securely by any means short of physical destruction (e.g., incineration). A 4.7 GB DVD-R full of one-time-pad data, if shredded into particles 1 mm<sup>2</sup> (0.0016 sq in) in size, leaves over 4 <a href="/wiki/Megabit" class="mw-redirect" title="Megabit">megabits</a> of data on each particle. <sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (November 2010)">citation needed</span></a></i>]</sup> In addition, the risk of compromise during transit (for example, a <a href="/wiki/Pickpocket" class="mw-redirect" title="Pickpocket">pickpocket</a> swiping, copying and replacing the pad) is likely to be much greater in practice than the likelihood of compromise for a cipher such as <a href="/wiki/Advanced_Encryption_Standard" title="Advanced Encryption Standard">AES</a>. Finally, the effort needed to manage one-time pad key material <a href="/wiki/Scalability" title="Scalability">scales</a> very badly for large networks of communicants—the number of pads required goes up as the <a href="/wiki/Quadratic_growth" title="Quadratic growth">square</a> of the number of users freely exchanging messages. For communication between only two persons, or a <a href="/wiki/Star_network" title="Star network">star network</a> topology, this is less of a problem. </p><p>The key material must be securely disposed of after use, to ensure the key material is never reused and to protect the messages sent.<sup id="cite_ref-Numbers_Stations_2-2" class="reference"><a href="#cite_note-Numbers_Stations-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Because the key material must be transported from one endpoint to another, and persist until the message is sent or received, it can be more vulnerable to <a href="/wiki/Computer_forensics" title="Computer forensics">forensic recovery</a> than the transient plaintext it protects (because of possible data remanence). </p> <div class="mw-heading mw-heading3"><h3 id="Authentication">Authentication</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=8" title="Edit section: Authentication"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>As traditionally used, one-time pads provide no <a href="/wiki/Authentication" title="Authentication">message authentication</a>, the lack of which can pose a security threat in real-world systems. For example, an attacker who knows that the message contains "meet jane and me tomorrow at three thirty pm" can derive the corresponding codes of the pad directly from the two known elements (the encrypted text and the known plaintext). The attacker can then replace that text by any other text of exactly the same length, such as "three thirty meeting is cancelled, stay home". The attacker's knowledge of the one-time pad is limited to this byte length, which must be maintained for any other content of the message to remain valid. This is different from <a href="/wiki/Malleability_(cryptography)" title="Malleability (cryptography)">malleability</a><sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> where the plaintext is not necessarily known. Without knowing the message, the attacker can also flip bits in a message sent with a one-time pad, without the recipient being able to detect it. Because of their similarities, attacks on one-time pads are similar to <a href="/wiki/Stream_cipher_attacks" title="Stream cipher attacks">attacks on stream ciphers</a>.<sup id="cite_ref-:0_27-0" class="reference"><a href="#cite_note-:0-27"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </p><p>Standard techniques to prevent this, such as the use of a <a href="/wiki/Message_authentication_code" title="Message authentication code">message authentication code</a> can be used along with a one-time pad system to prevent such attacks, as can classical methods such as variable length <a href="/wiki/Padding_(cryptography)" title="Padding (cryptography)">padding</a> and <a href="/wiki/Russian_copulation" title="Russian copulation">Russian copulation</a>, but they all lack the perfect security the OTP itself has. <a href="/wiki/Universal_hashing" title="Universal hashing">Universal hashing</a> provides a way to authenticate messages up to an arbitrary security bound (i.e., for any <span class="nowrap"><i>p</i> > 0</span>, a large enough hash ensures that even a computationally unbounded attacker's likelihood of successful forgery is less than <i>p</i>), but this uses additional random data from the pad, and some of these techniques remove the possibility of implementing the system without a computer. </p> <div class="mw-heading mw-heading3"><h3 id="Common_implementation_errors">Common implementation errors</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=9" title="Edit section: Common implementation errors"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Due to its relative simplicity of implementation, and due to its promise of perfect secrecy, one-time-pad enjoys high popularity among students learning about cryptography, especially as it is often the first algorithm to be presented and implemented during a course. Such "first" implementations often break the requirements for information theoretical security in one or more ways: </p> <ul><li><b>The pad is generated via some algorithm, that expands one or more small values into a longer "one-time-pad".</b> This applies equally to all algorithms, from insecure basic mathematical operations like square root decimal expansions, to complex, cryptographically secure pseudo-random random number generators (CSPRNGs). None of these implementations are one-time-pads, but <a href="/wiki/Stream_cipher" title="Stream cipher">stream ciphers</a> by definition. All one-time pads must be generated by a non-algorithmic process, e.g. by a <a href="/wiki/Hardware_random_number_generator" title="Hardware random number generator">hardware random number generator</a>.</li> <li><b>The pad is exchanged using non-information-theoretically secure methods.</b> If the one-time-pad is encrypted with a non-information theoretically secure algorithm for delivery, the security of the cryptosystem is only as secure as the insecure delivery mechanism. A common flawed delivery mechanism for one-time-pad is a standard <a href="/wiki/Hybrid_cryptosystem" title="Hybrid cryptosystem">hybrid cryptosystem</a> that relies on symmetric key cryptography for pad encryption, and asymmetric cryptography for symmetric key delivery. Common secure methods for one-time pad delivery are <a href="/wiki/Quantum_key_distribution" title="Quantum key distribution">quantum key distribution</a>, a <a href="/wiki/Sneakernet" title="Sneakernet">sneakernet</a> or <a href="/wiki/Courier" title="Courier">courier</a> service, or a <a href="/wiki/Dead_drop" title="Dead drop">dead drop</a>.</li> <li>The implementation does not feature an unconditionally secure authentication mechanism such as a <a href="/wiki/Message_authentication_code#One-time_MAC" title="Message authentication code">one-time MAC</a>.</li> <li>The pad is reused (exploited during the <a href="/wiki/Venona_project" title="Venona project">Venona project</a>, for example).<sup id="cite_ref-:2_28-0" class="reference"><a href="#cite_note-:2-28"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup></li> <li>The pad is not destroyed immediately after use.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Uses">Uses</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=10" title="Edit section: Uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Applicability">Applicability</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=11" title="Edit section: Applicability"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Despite its problems, the one-time-pad retains some practical interest. In some hypothetical espionage situations, the one-time pad might be useful because encryption and decryption can be computed by hand with only pencil and paper. Nearly all other high quality ciphers are entirely impractical without computers. In the modern world, however, computers (such as those embedded in <a href="/wiki/Mobile_phone" title="Mobile phone">mobile phones</a>) are so ubiquitous that possessing a computer suitable for performing conventional encryption (for example, a phone that can run concealed cryptographic software) will usually not attract suspicion. </p> <ul><li>The one-time-pad is the optimum cryptosystem with theoretically perfect secrecy.<sup id="cite_ref-Shannon_20-1" class="reference"><a href="#cite_note-Shannon-20"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup></li> <li>The one-time-pad is one of the most practical methods of encryption where one or both parties must do all work by hand, without the aid of a computer. This made it important in the pre-computer era, and it could conceivably still be useful in situations where possession of a computer is illegal or incriminating or where trustworthy computers are not available.</li> <li>One-time pads are practical in situations where two parties in a secure environment must be able to depart from one another and communicate from two separate secure environments with perfect secrecy.</li> <li>The one-time-pad can be used in <a href="/wiki/Superencryption" class="mw-redirect" title="Superencryption">superencryption</a>.<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup></li> <li>The algorithm most commonly associated with <a href="/wiki/Quantum_key_distribution" title="Quantum key distribution">quantum key distribution</a> is the one-time pad.<sup id="cite_ref-:1_30-0" class="reference"><a href="#cite_note-:1-30"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup></li> <li>The one-time pad is mimicked by <a href="/wiki/Stream_cipher" title="Stream cipher">stream ciphers</a>.<sup id="cite_ref-:0_27-1" class="reference"><a href="#cite_note-:0-27"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Numbers_station" title="Numbers station">Numbers stations</a> often send messages encrypted with a one-time pad.<sup id="cite_ref-Numbers_Stations_2-3" class="reference"><a href="#cite_note-Numbers_Stations-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading3"><h3 id="Quantum_and_post-quantum_cryptography">Quantum and post-quantum cryptography</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=12" title="Edit section: Quantum and post-quantum cryptography"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A common use of the one-time pad in <a href="/wiki/Quantum_cryptography" title="Quantum cryptography">quantum cryptography</a> is being used in association with <a href="/wiki/Quantum_key_distribution" title="Quantum key distribution">quantum key distribution</a> (QKD). QKD is typically associated with the one-time pad because it provides a way of distributing a long shared secret key securely and efficiently (assuming the existence of practical <a href="/wiki/Quantum_network" title="Quantum network">quantum networking</a> hardware). A QKD algorithm uses properties of quantum mechanical systems to let two parties agree on a shared, uniformly random string. Algorithms for QKD, such as <a href="/wiki/BB84" title="BB84">BB84</a>, are also able to determine whether an adversarial party has been attempting to intercept key material, and allow for a shared secret key to be agreed upon with relatively few messages exchanged and relatively low computational overhead. At a high level, the schemes work by taking advantage of the destructive way quantum states are measured to exchange a secret and detect tampering. In the original BB84 paper, it was proven that the one-time pad, with keys distributed via QKD, is a <a href="/wiki/Semantically-secure" class="mw-redirect" title="Semantically-secure">perfectly secure</a> encryption scheme.<sup id="cite_ref-:1_30-1" class="reference"><a href="#cite_note-:1-30"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> However, this result depends on the QKD scheme being implemented correctly in practice. Attacks on real-world QKD systems exist. For instance, many systems do not send a single photon (or other object in the desired quantum state) per bit of the key because of practical limitations, and an attacker could intercept and measure some of the photons associated with a message, gaining information about the key (i.e. leaking information about the pad), while passing along unmeasured photons corresponding to the same bit of the key.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> Combining QKD with a one-time pad can also loosen the requirements for key reuse. In 1982, <a href="/wiki/Charles_H._Bennett_(physicist)" title="Charles H. Bennett (physicist)">Bennett</a> and <a href="/wiki/Gilles_Brassard" title="Gilles Brassard">Brassard</a> showed that if a QKD protocol does not detect that an adversary was trying to intercept an exchanged key, then the key can safely be reused while preserving perfect secrecy.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </p><p>The one-time pad is an example of post-quantum cryptography, because perfect secrecy is a definition of security that does not depend on the computational resources of the adversary. Consequently, an adversary with a quantum computer would still not be able to gain any more information about a message encrypted with a one time pad than an adversary with just a classical computer. </p> <div class="mw-heading mw-heading3"><h3 id="Historical_uses">Historical uses</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=13" title="Edit section: Historical uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>One-time pads have been used in special circumstances since the early 1900s. In 1923, they were employed for diplomatic communications by the German diplomatic establishment.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Weimar_Republic" title="Weimar Republic">Weimar Republic</a> Diplomatic Service began using the method in about 1920. The breaking of poor <a href="/wiki/Union_of_Soviet_Socialist_Republics" class="mw-redirect" title="Union of Soviet Socialist Republics">Soviet</a> cryptography by the <a href="/wiki/United_Kingdom" title="United Kingdom">British</a>, with messages made public for political reasons in two instances in the 1920s (<a href="/wiki/All_Russian_Co-operative_Society#The_Arcos_Affair_of_1927" title="All Russian Co-operative Society">ARCOS case</a>), appear to have caused the Soviet Union to adopt one-time pads for some purposes by around 1930. <a href="/wiki/KGB" title="KGB">KGB</a> spies are also known to have used pencil and paper one-time pads more recently. Examples include Colonel <a href="/wiki/Rudolf_Abel" title="Rudolf Abel">Rudolf Abel</a>, who was arrested and convicted in <a href="/wiki/New_York_City" title="New York City">New York City</a> in the 1950s, and the 'Krogers' (i.e., <a href="/wiki/Morris_Cohen_(spy)" title="Morris Cohen (spy)">Morris</a> and <a href="/wiki/Lona_Cohen" title="Lona Cohen">Lona Cohen</a>), who were arrested and convicted of espionage in the <a href="/wiki/United_Kingdom" title="United Kingdom">United Kingdom</a> in the early 1960s. Both were found with physical one-time pads in their possession. </p><p>A number of nations have used one-time pad systems for their sensitive traffic. <a href="/wiki/Leo_Marks" title="Leo Marks">Leo Marks</a> reports that the British <a href="/wiki/Special_Operations_Executive" title="Special Operations Executive">Special Operations Executive</a> used one-time pads in World War II to encode traffic between its offices. One-time pads for use with its overseas agents were introduced late in the war.<sup id="cite_ref-marks_14-1" class="reference"><a href="#cite_note-marks-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> A few British one-time tape cipher machines include the <a href="/wiki/Rockex" title="Rockex">Rockex</a> and <a href="/wiki/Noreen" title="Noreen">Noreen</a>. The German <a href="/wiki/Stasi" title="Stasi">Stasi</a> Sprach Machine was also capable of using one time tape that East Germany, Russia, and even Cuba used to send encrypted messages to their agents.<sup id="cite_ref-Sprach_Machine_34-0" class="reference"><a href="#cite_note-Sprach_Machine-34"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> </p><p>The <a href="/wiki/World_War_II" title="World War II">World War II</a> voice <a href="/wiki/Scrambler" title="Scrambler">scrambler</a> <a href="/wiki/SIGSALY" title="SIGSALY">SIGSALY</a> was also a form of one-time system. It added noise to the signal at one end and removed it at the other end. The noise was distributed to the channel ends in the form of large shellac records that were manufactured in unique pairs. There were both starting synchronization and longer-term phase drift problems that arose and had to be solved before the system could be used.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p><p>The <a href="/wiki/Moscow-Washington_hotline" class="mw-redirect" title="Moscow-Washington hotline">hotline</a> between <a href="/wiki/Moscow" title="Moscow">Moscow</a> and <a href="/wiki/Washington_D.C." class="mw-redirect" title="Washington D.C.">Washington D.C.</a>, established in 1963 after the 1962 <a href="/wiki/Cuban_Missile_Crisis" title="Cuban Missile Crisis">Cuban Missile Crisis</a>, used <a href="/wiki/Teleprinter" title="Teleprinter">teleprinters</a> protected by a commercial one-time tape system. Each country prepared the keying tapes used to encode its messages and delivered them via their embassy in the other country. A unique advantage of the OTP in this case was that neither country had to reveal more sensitive encryption methods to the other.<sup id="cite_ref-36" class="reference"><a href="#cite_note-36"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> </p><p>U.S. Army Special Forces used one-time pads in Vietnam. By using Morse code with one-time pads and continuous wave radio transmission (the carrier for Morse code), they achieved both secrecy and reliable communications.<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> </p><p>Starting in 1988, the <a href="/wiki/African_National_Congress" title="African National Congress">African National Congress</a> (ANC) used disk-based one-time pads as part of a <a href="/wiki/Secure_communication" title="Secure communication">secure communication</a> system between ANC leaders outside <a href="/wiki/South_Africa" title="South Africa">South Africa</a> and in-country operatives as part of Operation Vula,<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> a successful effort to build a resistance network inside South Africa. Random numbers on the disk were erased after use. A Belgian flight attendant acted as courier to bring in the pad disks. A regular resupply of new disks was needed as they were used up fairly quickly. One problem with the system was that it could not be used for secure data storage. Later Vula added a stream cipher keyed by book codes to solve this problem.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> </p><p>A related notion is the <a href="/wiki/Code_(cryptography)#One-time_code" title="Code (cryptography)">one-time code</a>—a signal, used only once; e.g., "Alpha" for "mission completed", "Bravo" for "mission failed" or even "Torch" for "<a href="/wiki/Operation_Torch" title="Operation Torch">Allied invasion of French Northern Africa</a>"<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> cannot be "decrypted" in any reasonable sense of the word. Understanding the message will require additional information, often 'depth' of repetition, or some <a href="/wiki/Traffic_analysis" title="Traffic analysis">traffic analysis</a>. However, such strategies (though often used by real operatives, and <a href="/wiki/Baseball" title="Baseball">baseball</a> coaches)<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> are not a cryptographic one-time pad in any significant sense. </p> <div class="mw-heading mw-heading3"><h3 id="NSA">NSA</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=14" title="Edit section: NSA"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>At least into the 1970s, the U.S. <a href="/wiki/National_Security_Agency" title="National Security Agency">National Security Agency</a> (NSA) produced a variety of manual one-time pads, both general purpose and specialized, with 86,000 one-time pads produced in fiscal year 1972. Special purpose pads were produced for what the NSA called "pro forma" systems, where "the basic framework, form or format of every message text is identical or nearly so; the same kind of information, message after message, is to be presented in the same order, and only specific values, like numbers, change with each message." Examples included nuclear launch messages and radio direction finding reports (COMUS).<sup id="cite_ref-boaklectures1_42-0" class="reference"><a href="#cite_note-boaklectures1-42"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: pp. 16–18">: pp. 16–18 </span></sup> </p><p>General purpose pads were produced in several formats, a simple list of random letters (DIANA) or just numbers (CALYPSO), tiny pads for covert agents (MICKEY MOUSE), and pads designed for more rapid encoding of short messages, at the cost of lower density. One example, ORION, had 50 rows of plaintext alphabets on one side and the corresponding random cipher text letters on the other side. By placing a sheet on top of a piece of <a href="/wiki/Carbon_paper" title="Carbon paper">carbon paper</a> with the carbon face up, one could circle one letter in each row on one side and the corresponding letter on the other side would be circled by the carbon paper. Thus one ORION sheet could quickly encode or decode a message up to 50 characters long. Production of ORION pads required printing both sides in exact registration, a difficult process, so NSA switched to another pad format, MEDEA, with 25 rows of paired alphabets and random characters. (<i>See</i> <a href="https://commons.wikimedia.org/wiki/Category:NSA_one-time_pads" class="extiw" title="commons:Category:NSA one-time pads">Commons:Category:NSA one-time pads</a> for illustrations.) </p><p>The NSA also built automated systems for the "centralized headquarters of CIA and Special Forces units so that they can efficiently process the many separate one-time pad messages to and from individual pad holders in the field".<sup id="cite_ref-boaklectures1_42-1" class="reference"><a href="#cite_note-boaklectures1-42"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: pp. 21–26">: pp. 21–26 </span></sup> </p><p>During World War II and into the 1950s, the U.S. made extensive use of one-time tape systems. In addition to providing confidentiality, circuits secured by one-time tape ran continually, even when there was no traffic, thus protecting against <a href="/wiki/Traffic_analysis" title="Traffic analysis">traffic analysis</a>. In 1955, NSA produced some 1,660,000 rolls of one time tape. Each roll was 8 inches in diameter, contained 100,000 characters, lasted 166 minutes and cost $4.55 to produce. By 1972, only 55,000 rolls were produced, as one-time tapes were replaced by <a href="/wiki/Rotor_machine" title="Rotor machine">rotor machines</a> such as SIGTOT, and later by electronic devices based on <a href="/wiki/Shift_registers" class="mw-redirect" title="Shift registers">shift registers</a>.<sup id="cite_ref-boaklectures1_42-2" class="reference"><a href="#cite_note-boaklectures1-42"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: pp. 39–44">: pp. 39–44 </span></sup> The NSA describes one-time tape systems like <a href="/wiki/5-UCO" title="5-UCO">5-UCO</a> and SIGTOT as being used for intelligence traffic until the introduction of the electronic cipher based <a href="/wiki/KW-26" title="KW-26">KW-26</a> in 1957.<sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Exploits">Exploits</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=15" title="Edit section: Exploits"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>While one-time pads provide perfect secrecy if generated and used properly, small mistakes can lead to successful cryptanalysis: </p> <ul><li>In 1944–1945, the <a href="/wiki/U.S._Army" class="mw-redirect" title="U.S. Army">U.S. Army</a>'s <a href="/wiki/Signals_Intelligence_Service" class="mw-redirect" title="Signals Intelligence Service">Signals Intelligence Service</a> was able to solve a one-time pad system used by the German Foreign Office for its high-level traffic, codenamed GEE.<sup id="cite_ref-44" class="reference"><a href="#cite_note-44"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> GEE was insecure because the pads were not sufficiently random—the machine used to generate the pads produced predictable output.</li> <li>In 1945, the US discovered that <a href="/wiki/Canberra" title="Canberra">Canberra</a>–<a href="/wiki/Moscow" title="Moscow">Moscow</a> messages were being encrypted first using a code-book and then using a one-time pad. However, the one-time pad used was the same one used by Moscow for <a href="/wiki/Washington,_D.C." title="Washington, D.C.">Washington, D.C.</a>–Moscow messages. Combined with the fact that some of the Canberra–Moscow messages included known British government documents, this allowed some of the encrypted messages to be broken.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (June 2021)">citation needed</span></a></i>]</sup></li> <li>One-time pads were employed by <a href="/wiki/Soviet_Union" title="Soviet Union">Soviet</a> espionage agencies for covert communications with agents and agent controllers. Analysis has shown that these pads were generated by typists using actual typewriters. This method is not truly random, as it makes the pads more likely to contain certain convenient key sequences more frequently. This proved to be generally effective because the pads were still somewhat unpredictable because the typists were not following rules, and different typists produced different patterns of pads. Without copies of the key material used, only some defect in the generation method or reuse of keys offered much hope of cryptanalysis. Beginning in the late 1940s, US and UK intelligence agencies were able to break some of the Soviet one-time pad traffic to <a href="/wiki/Moscow" title="Moscow">Moscow</a> during WWII as a result of errors made in generating and distributing the key material. One suggestion is that Moscow Centre personnel were somewhat rushed by the presence of German troops just outside Moscow in late 1941 and early 1942, and they produced more than one copy of the same key material during that period. This decades-long effort was finally codenamed <a href="/wiki/Venona_project" title="Venona project">VENONA</a> (BRIDE had been an earlier name); it produced a considerable amount of information. Even so, only a small percentage of the intercepted messages were either fully or partially decrypted (a few thousand out of several hundred thousand).<sup id="cite_ref-:2_28-1" class="reference"><a href="#cite_note-:2-28"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup></li> <li>The one-time tape systems used by the U.S. employed electromechanical mixers to combine bits from the message and the one-time tape. These mixers radiated considerable electromagnetic energy that could be picked up by an adversary at some distance from the encryption equipment. This effect, first noticed by <a href="/wiki/Bell_Labs" title="Bell Labs">Bell Labs</a> during World War II, could allow interception and recovery of the plaintext of messages being transmitted, a vulnerability code-named <a href="/wiki/Tempest_(codename)" title="Tempest (codename)">Tempest</a>.<sup id="cite_ref-boaklectures1_42-3" class="reference"><a href="#cite_note-boaklectures1-42"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: pp. 89 ff">: pp. 89 ff </span></sup></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=16" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col" style="column-width: 25em;"> <ul><li><i><a href="/wiki/Agrippa_(A_Book_of_the_Dead)" title="Agrippa (A Book of the Dead)">Agrippa (A Book of the Dead)</a></i></li> <li><a href="/wiki/Information_theoretic_security" class="mw-redirect" title="Information theoretic security">Information theoretic security</a></li> <li><a href="/wiki/Numbers_station" title="Numbers station">Numbers station</a></li> <li><a href="/wiki/One-time_password" title="One-time password">One-time password</a></li> <li><a href="/wiki/Session_key" title="Session key">Session key</a></li> <li><a href="/wiki/Steganography" title="Steganography">Steganography</a></li> <li><a href="/wiki/Tradecraft" title="Tradecraft">Tradecraft</a></li> <li><a href="/wiki/Unicity_distance" title="Unicity distance">Unicity distance</a></li> <li><a href="/wiki/No-hiding_theorem" title="No-hiding theorem">No-hiding theorem</a></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=17" title="Edit section: Notes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text">The actual length of a plaintext message can hidden by the addition of extraneous parts, called <a href="/wiki/Padding_(cryptography)" title="Padding (cryptography)">padding</a>. For instance, a 21-character ciphertext could conceal a 5-character message with some padding convention (e.g. "-PADDING- HELLO -XYZ-") as much as an actual 21-character message: an observer can thus only deduce the maximum possible length of the significant text, not its exact length.</span> </li> <li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text">That is to say, the "<b>information gain</b>" or <a href="/wiki/Kullback%E2%80%93Leibler_divergence" title="Kullback–Leibler divergence">Kullback–Leibler divergence</a> of the plaintext message from the ciphertext message is zero.</span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text">Most asymmetric encryption algorithms rely on the facts that the best known algorithms for prime factorization and computing discrete logarithms are superpolynomial time. There is a strong belief that these problems are not solvable by a Turing machine in time that scales polynomially with input length, rendering them difficult (hopefully, prohibitively so) to be broken via cryptographic attacks. However, this has not been proven.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=18" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFLugrin2023" class="citation cs2">Lugrin, Thomas (2023), Mulder, Valentin; Mermoud, Alain; Lenders, Vincent; Tellenbach, Bernhard (eds.), "One-Time Pad", <i>Trends in Data Protection and Encryption Technologies</i>, Cham: Springer Nature Switzerland, pp. 3–6, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1007%2F978-3-031-33386-6_1">10.1007/978-3-031-33386-6_1</a></span>, <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-3-031-33386-6" title="Special:BookSources/978-3-031-33386-6"><bdi>978-3-031-33386-6</bdi></a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Trends+in+Data+Protection+and+Encryption+Technologies&rft.atitle=One-Time+Pad&rft.pages=3-6&rft.date=2023&rft_id=info%3Adoi%2F10.1007%2F978-3-031-33386-6_1&rft.isbn=978-3-031-33386-6&rft.aulast=Lugrin&rft.aufirst=Thomas&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-Numbers_Stations-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-Numbers_Stations_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Numbers_Stations_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Numbers_Stations_2-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Numbers_Stations_2-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20141018031055/http://www.numbers-stations.com/intro">"Intro to Numbers Stations"</a>. Archived from <a rel="nofollow" class="external text" href="http://www.numbers-stations.com/intro">the original</a> on 18 October 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">13 September</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Intro+to+Numbers+Stations&rft_id=http%3A%2F%2Fwww.numbers-stations.com%2Fintro&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20140314175211/http://www.cryptomuseum.com/crypto/otp.htm">"One-Time Pad (OTP)"</a>. Cryptomuseum.com. Archived from <a rel="nofollow" class="external text" href="http://www.cryptomuseum.com/crypto/otp.htm">the original</a> on 2014-03-14<span class="reference-accessdate">. Retrieved <span class="nowrap">2014-03-17</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=One-Time+Pad+%28OTP%29&rft.pub=Cryptomuseum.com&rft_id=http%3A%2F%2Fwww.cryptomuseum.com%2Fcrypto%2Fotp.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-shannon-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-shannon_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-shannon_4-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFShannon1949" class="citation journal cs1">Shannon, Claude (1949). <a rel="nofollow" class="external text" href="https://www.cs.virginia.edu/~evans/greatworks/shannon1949.pdf">"Communication Theory of Secrecy Systems"</a> <span class="cs1-format">(PDF)</span>. <i>Bell System Technical Journal</i>. <b>28</b> (4): 656–715. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fj.1538-7305.1949.tb00928.x">10.1002/j.1538-7305.1949.tb00928.x</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Bell+System+Technical+Journal&rft.atitle=Communication+Theory+of+Secrecy+Systems&rft.volume=28&rft.issue=4&rft.pages=656-715&rft.date=1949&rft_id=info%3Adoi%2F10.1002%2Fj.1538-7305.1949.tb00928.x&rft.aulast=Shannon&rft.aufirst=Claude&rft_id=https%3A%2F%2Fwww.cs.virginia.edu%2F~evans%2Fgreatworks%2Fshannon1949.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFrank_Miller1882" class="citation cs1">Frank Miller (1882). <span class="cs1-ws-icon" title="s:Telegraphic Code to Insure Privacy and Secrecy in the Transmission of Telegrams"><a class="external text" href="https://en.wikisource.org/wiki/Telegraphic_Code_to_Insure_Privacy_and_Secrecy_in_the_Transmission_of_Telegrams"><i>Telegraphic Code to Insure Privacy and Secrecy in the Transmission of Telegrams</i> </a></span> – via <a href="/wiki/Wikisource" title="Wikisource">Wikisource</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Telegraphic+Code+to+Insure+Privacy+and+Secrecy+in+the+Transmission+of+Telegrams&rft.date=1882&rft.au=Frank+Miller&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-BELLOVIN1-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-BELLOVIN1_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-BELLOVIN1_6-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBellovin2011" class="citation journal cs1">Bellovin, Steven M. 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Retrieved <span class="nowrap">3 February</span> 2016</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=google.com&rft.atitle=%27Secret+signaling+system+patent%27+on+Google.Com&rft_id=https%3A%2F%2Fpatents.google.com%2Fpatent%2FUS1310719&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKahn1996" class="citation book cs1"><a href="/wiki/David_Kahn_(writer)" title="David Kahn (writer)">Kahn, David</a> (1996). <a href="/wiki/The_Codebreakers" title="The Codebreakers"><i>The Codebreakers</i></a>. <a href="/wiki/Macmillan_Publishers_(United_States)" class="mw-redirect" title="Macmillan Publishers (United States)">Macmillan</a>. pp. 397–8. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-684-83130-5" title="Special:BookSources/978-0-684-83130-5"><bdi>978-0-684-83130-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Codebreakers&rft.pages=397-8&rft.pub=Macmillan&rft.date=1996&rft.isbn=978-0-684-83130-5&rft.aulast=Kahn&rft.aufirst=David&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.ranum.com/security/computer_security/papers/otp-faq">"One-Time-Pad (Vernam's Cipher) Frequently Asked Questions, with photo"</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20060507212354/http://www.ranum.com/security/computer_security/papers/otp-faq/">Archived</a> from the original on 2006-05-07<span class="reference-accessdate">. Retrieved <span class="nowrap">2006-05-12</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=One-Time-Pad+%28Vernam%27s+Cipher%29+Frequently+Asked+Questions%2C+with+photo&rft_id=http%3A%2F%2Fwww.ranum.com%2Fsecurity%2Fcomputer_security%2Fpapers%2Fotp-faq&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSavory,_Stuart2001" class="citation web cs1 cs1-prop-foreign-lang-source">Savory, Stuart (2001). <a rel="nofollow" class="external text" href="https://www.ciphermachinesandcryptology.com/img/otp/otpbooklet1.jpg">"Chiffriergerätebau : One-Time-Pad, with photo"</a> (in German). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110530202013/http://users.telenet.be/d.rijmenants/pics/otpbooklet1.jpg">Archived</a> from the original on 2011-05-30<span class="reference-accessdate">. Retrieved <span class="nowrap">2006-07-24</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Chiffrierger%C3%A4tebau+%3A+One-Time-Pad%2C+with+photo&rft.date=2001&rft.au=Savory%2C+Stuart&rft_id=https%3A%2F%2Fwww.ciphermachinesandcryptology.com%2Fimg%2Fotp%2Fotpbooklet1.jpg&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-kahn-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-kahn_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-kahn_11-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-kahn_11-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKahn1967" class="citation book cs1"><a href="/wiki/David_Kahn_(writer)" title="David Kahn (writer)">Kahn, David</a> (1967). <a href="/wiki/The_Codebreakers" title="The Codebreakers"><i>The Codebreakers</i></a>. <a href="/wiki/Macmillan_Publishers_(United_States)" class="mw-redirect" title="Macmillan Publishers (United States)">Macmillan</a>. pp. 398 ff. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-684-83130-5" title="Special:BookSources/978-0-684-83130-5"><bdi>978-0-684-83130-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Codebreakers&rft.pages=398+ff&rft.pub=Macmillan&rft.date=1967&rft.isbn=978-0-684-83130-5&rft.aulast=Kahn&rft.aufirst=David&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-bio-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-bio_12-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJohn_Markoff2011" class="citation news cs1"><a href="/wiki/John_Markoff" title="John Markoff">John Markoff</a> (July 25, 2011). <a rel="nofollow" class="external text" href="https://www.nytimes.com/2011/07/26/science/26code.html?ref=science">"Codebook Shows an Encryption Form Dates Back to Telegraphs"</a>. <i><a href="/wiki/The_New_York_Times" title="The New York Times">The New York Times</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130521201312/http://www.nytimes.com/2011/07/26/science/26code.html?ref=science">Archived</a> from the original on May 21, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-07-26</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+New+York+Times&rft.atitle=Codebook+Shows+an+Encryption+Form+Dates+Back+to+Telegraphs&rft.date=2011-07-25&rft.au=John+Markoff&rft_id=https%3A%2F%2Fwww.nytimes.com%2F2011%2F07%2F26%2Fscience%2F26code.html%3Fref%3Dscience&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPengCuiSong2021" class="citation journal cs1">Peng, Weiping; Cui, Shuang; Song, Cheng (2021-01-20). Raja, Gulistan (ed.). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817086">"One-time-pad cipher algorithm based on confusion mapping and DNA storage technology"</a>. <i>PLOS ONE</i>. <b>16</b> (1): e0245506. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2021PLoSO..1645506P">2021PLoSO..1645506P</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1371%2Fjournal.pone.0245506">10.1371/journal.pone.0245506</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1932-6203">1932-6203</a>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817086">7817086</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/33471849">33471849</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=PLOS+ONE&rft.atitle=One-time-pad+cipher+algorithm+based+on+confusion+mapping+and+DNA+storage+technology&rft.volume=16&rft.issue=1&rft.pages=e0245506&rft.date=2021-01-20&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC7817086%23id-name%3DPMC&rft_id=info%3Abibcode%2F2021PLoSO..1645506P&rft_id=info%3Apmid%2F33471849&rft_id=info%3Adoi%2F10.1371%2Fjournal.pone.0245506&rft.issn=1932-6203&rft.aulast=Peng&rft.aufirst=Weiping&rft.au=Cui%2C+Shuang&rft.au=Song%2C+Cheng&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC7817086&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-marks-14"><span class="mw-cite-backlink">^ <a href="#cite_ref-marks_14-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-marks_14-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMarks1998" class="citation book cs1">Marks, Leo (1998). <a rel="nofollow" class="external text" href="https://archive.org/details/betweensilkcyani00leom"><i>Between Silk and Cyanide: a Codemaker's Story, 1941–1945</i></a>. HarperCollins. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-684-86780-9" title="Special:BookSources/978-0-684-86780-9"><bdi>978-0-684-86780-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Between+Silk+and+Cyanide%3A+a+Codemaker%27s+Story%2C+1941%E2%80%931945&rft.pub=HarperCollins&rft.date=1998&rft.isbn=978-0-684-86780-9&rft.aulast=Marks&rft.aufirst=Leo&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fbetweensilkcyani00leom&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-kotelnikov-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-kotelnikov_15-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSergei_N_Molotkov_(Institute_of_Solid-State_Physics,_Russian_Academy_of_Sciences,_Chernogolovka,_Moscow_region,_Russian_Federation)2006" class="citation journal cs1">Sergei N Molotkov (Institute of Solid-State Physics, Russian Academy of Sciences, Chernogolovka, Moscow region, Russian Federation) (22 February 2006). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20081210092826/http://www.turpion.org/php/paper.phtml?journal_id=pu&paper_id=6050">"Quantum cryptography and V A Kotel'nikov's one-time key and sampling theorems"</a>. <i>Physics-Uspekhi</i>. <b>49</b> (7): 750–761. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2006PhyU...49..750M">2006PhyU...49..750M</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1070%2FPU2006v049n07ABEH006050">10.1070/PU2006v049n07ABEH006050</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:118764598">118764598</a>. Archived from <a rel="nofollow" class="external text" href="http://www.turpion.org/php/paper.phtml?journal_id=pu&paper_id=6050">the original</a> on 2008-12-10<span class="reference-accessdate">. Retrieved <span class="nowrap">2009-05-03</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Physics-Uspekhi&rft.atitle=Quantum+cryptography+and+V+A+Kotel%27nikov%27s+one-time+key+and+sampling+theorems&rft.volume=49&rft.issue=7&rft.pages=750-761&rft.date=2006-02-22&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A118764598%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1070%2FPU2006v049n07ABEH006050&rft_id=info%3Abibcode%2F2006PhyU...49..750M&rft.au=Sergei+N+Molotkov+%28Institute+of+Solid-State+Physics%2C+Russian+Academy+of+Sciences%2C+Chernogolovka%2C+Moscow+region%2C+Russian+Federation%29&rft_id=http%3A%2F%2Fwww.turpion.org%2Fphp%2Fpaper.phtml%3Fjournal_id%3Dpu%26paper_id%3D6050&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span><span class="cs1-maint citation-comment"><code class="cs1-code">{{<a href="/wiki/Template:Cite_journal" title="Template:Cite journal">cite journal</a>}}</code>: CS1 maint: multiple names: authors list (<a href="/wiki/Category:CS1_maint:_multiple_names:_authors_list" title="Category:CS1 maint: multiple names: authors list">link</a>)</span> PACS numbers: 01.10.Fv, 03.67.Dd, 89.70.+c and openly in Russian <a rel="nofollow" class="external text" href="http://www.ufn.ru/ru/articles/2006/7/k/">Квантовая криптография и теоремы В.А. Котельникова об одноразовых ключах и об отсчетах. УФН</a></span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMoscaTappde_Wolf2000" class="citation arxiv cs1">Mosca, Michele; Tapp, Alain; de Wolf, Ronald (2000-03-27). "Private Quantum Channels and the Cost of Randomizing Quantum Information". <a href="/wiki/ArXiv_(identifier)" class="mw-redirect" title="ArXiv (identifier)">arXiv</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://arxiv.org/abs/quant-ph/0003101">quant-ph/0003101</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=preprint&rft.jtitle=arXiv&rft.atitle=Private+Quantum+Channels+and+the+Cost+of+Randomizing+Quantum+Information&rft.date=2000-03-27&rft_id=info%3Aarxiv%2Fquant-ph%2F0003101&rft.aulast=Mosca&rft.aufirst=Michele&rft.au=Tapp%2C+Alain&rft.au=de+Wolf%2C+Ronald&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRobert_Wallace_and_H._Keith_Melton,_with_Henry_R._Schlesinger2008" class="citation book cs1">Robert Wallace and H. Keith Melton, with Henry R. Schlesinger (2008). <a rel="nofollow" class="external text" href="https://archive.org/details/spycraftsecrethi00wall_0/page/436"><i>Spycraft: The Secret History of the CIA's Spytechs, from Communism to al-Qaeda</i></a>. New York: <a href="/wiki/Dutton_Penguin" class="mw-redirect" title="Dutton Penguin">Dutton</a>. p. 436. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-525-94980-0" title="Special:BookSources/978-0-525-94980-0"><bdi>978-0-525-94980-0</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Spycraft%3A+The+Secret+History+of+the+CIA%27s+Spytechs%2C+from+Communism+to+al-Qaeda&rft.place=New+York&rft.pages=436&rft.pub=Dutton&rft.date=2008&rft.isbn=978-0-525-94980-0&rft.au=Robert+Wallace+and+H.+Keith+Melton%2C+with+Henry+R.+Schlesinger&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fspycraftsecrethi00wall_0%2Fpage%2F436&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-schneierotp-18"><span class="mw-cite-backlink">^ <a href="#cite_ref-schneierotp_18-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-schneierotp_18-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-schneierotp_18-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-schneierotp_18-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSchneier" class="citation web cs1">Schneier, Bruce. <a rel="nofollow" class="external text" href="http://www.schneier.com/crypto-gram-0210.html#7">"One-Time Pads"</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20050403200231/http://www.schneier.com/crypto-gram-0210.html#7">Archived</a> from the original on 2005-04-03.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=One-Time+Pads&rft.aulast=Schneier&rft.aufirst=Bruce&rft_id=http%3A%2F%2Fwww.schneier.com%2Fcrypto-gram-0210.html%237&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-Shannon-20"><span class="mw-cite-backlink">^ <a href="#cite_ref-Shannon_20-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Shannon_20-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFShannon1949" class="citation journal cs1">Shannon, Claude E. (October 1949). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120120001953/http://www.alcatel-lucent.com/bstj/vol28-1949/articles/bstj28-4-656.pdf">"Communication Theory of Secrecy Systems"</a> <span class="cs1-format">(PDF)</span>. <i>Bell System Technical Journal</i>. <b>28</b> (4): 656–715. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fj.1538-7305.1949.tb00928.x">10.1002/j.1538-7305.1949.tb00928.x</a>. <a href="/wiki/Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<a rel="nofollow" class="external text" href="https://hdl.handle.net/10338.dmlcz%2F119717">10338.dmlcz/119717</a>. Archived from <a rel="nofollow" class="external text" href="http://www3.alcatel-lucent.com/bstj/vol28-1949/articles/bstj28-4-656.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 2012-01-20<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-12-21</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Bell+System+Technical+Journal&rft.atitle=Communication+Theory+of+Secrecy+Systems&rft.volume=28&rft.issue=4&rft.pages=656-715&rft.date=1949-10&rft_id=info%3Ahdl%2F10338.dmlcz%2F119717&rft_id=info%3Adoi%2F10.1002%2Fj.1538-7305.1949.tb00928.x&rft.aulast=Shannon&rft.aufirst=Claude+E.&rft_id=http%3A%2F%2Fwww3.alcatel-lucent.com%2Fbstj%2Fvol28-1949%2Farticles%2Fbstj28-4-656.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLars_R._KnudsenMatthew_Robshaw2011" class="citation book cs1">Lars R. Knudsen & Matthew Robshaw (2011). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=YiZKt_FcmYQC&q=security+concerns+for+high+quality+cipher&pg=PA11"><i>The Block Cipher Companion</i></a>. Springer Science & Business Media. pp. 1–14. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-3642173424" title="Special:BookSources/978-3642173424"><bdi>978-3642173424</bdi></a><span class="reference-accessdate">. Retrieved <span class="nowrap">26 July</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Block+Cipher+Companion&rft.pages=1-14&rft.pub=Springer+Science+%26+Business+Media&rft.date=2011&rft.isbn=978-3642173424&rft.au=Lars+R.+Knudsen&rft.au=Matthew+Robshaw&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DYiZKt_FcmYQC%26q%3Dsecurity%2Bconcerns%2Bfor%2Bhigh%2Bquality%2Bcipher%26pg%3DPA11&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSingh2000" class="citation book cs1">Singh, Simon (2000). <a rel="nofollow" class="external text" href="https://archive.org/details/codebook00simo/page/123"><i>The Code Book</i></a>. United States: Anchor Books. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/codebook00simo/page/123">123</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-385-49532-5" title="Special:BookSources/978-0-385-49532-5"><bdi>978-0-385-49532-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Code+Book&rft.place=United+States&rft.pages=123&rft.pub=Anchor+Books&rft.date=2000&rft.isbn=978-0-385-49532-5&rft.aulast=Singh&rft.aufirst=Simon&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fcodebook00simo%2Fpage%2F123&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-nsa-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-nsa_25-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20090510052927/http://www.nsa.gov/about/_files/cryptologic_heritage/publications/coldwar/venona_story.pdf">"The Translations and KGB Cryptographic Systems"</a> <span class="cs1-format">(PDF)</span>. <i>The Venona Story</i>. <a href="/wiki/Fort_Meade,_Maryland" title="Fort Meade, Maryland">Fort Meade, Maryland</a>: <a href="/wiki/National_Security_Agency" title="National Security Agency">National Security Agency</a>. 2004-01-15. pp. 26–27 (28–29th of 63 in PDF). Archived from <a rel="nofollow" class="external text" href="http://www.nsa.gov/about/_files/cryptologic_heritage/publications/coldwar/venona_story.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 2009-05-10<span class="reference-accessdate">. Retrieved <span class="nowrap">2009-05-03</span></span>. <q>KGB's cryptographic material manufacturing center in the Soviet Union apparently reused some of the pages from one-time pads. This provided <a href="/wiki/Arlington_Hall" title="Arlington Hall">Arlington Hall</a> with an opening.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Venona+Story&rft.atitle=The+Translations+and+KGB+Cryptographic+Systems&rft.pages=26-27+%2828-29th+of+63+in+PDF%29&rft.date=2004-01-15&rft_id=http%3A%2F%2Fwww.nsa.gov%2Fabout%2F_files%2Fcryptologic_heritage%2Fpublications%2Fcoldwar%2Fvenona_story.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSafavi-Naini2008" class="citation book cs1">Safavi-Naini, Reihaneh (2008). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=ySZwUT4nyPsC&q=malleable+one+time+pad&pg=PR1"><i>Information Theoretic Security: Third International Conference, ICITS 2008, Calgary, Canada, August 10–13, 2008, Proceedings</i></a>. Springer Science & Business Media. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-3540850922" title="Special:BookSources/978-3540850922"><bdi>978-3540850922</bdi></a> – via Google Books.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Information+Theoretic+Security%3A+Third+International+Conference%2C+ICITS+2008%2C+Calgary%2C+Canada%2C+August+10%E2%80%9313%2C+2008%2C+Proceedings&rft.pub=Springer+Science+%26+Business+Media&rft.date=2008&rft.isbn=978-3540850922&rft.aulast=Safavi-Naini&rft.aufirst=Reihaneh&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DySZwUT4nyPsC%26q%3Dmalleable%2Bone%2Btime%2Bpad%26pg%3DPR1&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-:0-27"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_27-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_27-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBoneh" class="citation web cs1">Boneh, Dan. <a rel="nofollow" class="external text" href="https://www.coursera.org/lecture/crypto/attacks-on-stream-ciphers-and-the-one-time-pad-euFJx">"Attacks on Stream Ciphers and The One Time Pad - Course overview and stream ciphers"</a>. <i>Coursera</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2022-03-21</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Coursera&rft.atitle=Attacks+on+Stream+Ciphers+and+The+One+Time+Pad+-+Course+overview+and+stream+ciphers&rft.aulast=Boneh&rft.aufirst=Dan&rft_id=https%3A%2F%2Fwww.coursera.org%2Flecture%2Fcrypto%2Fattacks-on-stream-ciphers-and-the-one-time-pad-euFJx&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-:2-28"><span class="mw-cite-backlink">^ <a href="#cite_ref-:2_28-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:2_28-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20090510052927/http://www.nsa.gov/about/_files/cryptologic_heritage/publications/coldwar/venona_story.pdf">"The Venona Translations"</a> <span class="cs1-format">(PDF)</span>. <i>The Venona Story</i>. <a href="/wiki/Fort_Meade,_Maryland" title="Fort Meade, Maryland">Fort Meade, Maryland</a>: <a href="/wiki/National_Security_Agency" title="National Security Agency">National Security Agency</a>. 2004-01-15. p. 17th (of 63 in PDF) but marked 15. Archived from <a rel="nofollow" class="external text" href="http://www.nsa.gov/about/_files/cryptologic_heritage/publications/coldwar/venona_story.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 2009-05-10<span class="reference-accessdate">. Retrieved <span class="nowrap">2009-05-03</span></span>. <q>Arlington Hall's ability to read the VENONA messages was spotty, being a function of the underlying code, key changes, and the lack of volume. Of the message traffic from the KGB New York office to Moscow, 49 percent of the 1944 messages and 15 percent of the 1943 messages were readable, but this was true of only 1.8 percent of the 1942 messages. For the 1945 KGB Washington office to Moscow messages, only 1.5 percent were readable. About 50 percent of the 1943 GRU-Naval Washington to Moscow/Moscow to Washington messages were read but none from any other year.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Venona+Story&rft.atitle=The+Venona+Translations&rft.pages=17th+%28of+63+in+PDF%29+but+marked+15&rft.date=2004-01-15&rft_id=http%3A%2F%2Fwww.nsa.gov%2Fabout%2F_files%2Fcryptologic_heritage%2Fpublications%2Fcoldwar%2Fvenona_story.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text">A "way to combine multiple block algorithms" so that "a cryptanalyst must break both algorithms" in §15.8 of <i>Applied Cryptography, Second Edition: Protocols, Algorithms, and Source Code in C</i> by Bruce Schneier. Wiley Computer Publishing, John Wiley & Sons, Inc.</span> </li> <li id="cite_note-:1-30"><span class="mw-cite-backlink">^ <a href="#cite_ref-:1_30-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:1_30-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBennettBrassard1984" class="citation journal cs1">Bennett, Charles; Brassard, Giles (1984). "Quantum cryptography: Public key distribution and coin tossing". <i>Theoretical Computer Science</i>. <b>560</b>: 7–11. <a href="/wiki/ArXiv_(identifier)" class="mw-redirect" title="ArXiv (identifier)">arXiv</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://arxiv.org/abs/2003.06557">2003.06557</a></span>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.tcs.2014.05.025">10.1016/j.tcs.2014.05.025</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:27022972">27022972</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Theoretical+Computer+Science&rft.atitle=Quantum+cryptography%3A+Public+key+distribution+and+coin+tossing&rft.volume=560&rft.pages=7-11&rft.date=1984&rft_id=info%3Aarxiv%2F2003.06557&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A27022972%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1016%2Fj.tcs.2014.05.025&rft.aulast=Bennett&rft.aufirst=Charles&rft.au=Brassard%2C+Giles&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span> Note: This paper was published originally in 1984, but was retracted, and the version on ArXiv is a reprint from 2014 of the 1984 paper.</span> </li> <li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDušekHaderkaHendrych1999" class="citation journal cs1">Dušek, Miloslav; Haderka, Ondřej; Hendrych, Martin (1999-10-01). <a rel="nofollow" class="external text" href="https://www.sciencedirect.com/science/article/pii/S0030401899004198">"Generalized beam-splitting attack in quantum cryptography with dim coherent states"</a>. <i>Optics Communications</i>. <b>169</b> (1): 103–108. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1999OptCo.169..103D">1999OptCo.169..103D</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2FS0030-4018%2899%2900419-8">10.1016/S0030-4018(99)00419-8</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0030-4018">0030-4018</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Optics+Communications&rft.atitle=Generalized+beam-splitting+attack+in+quantum+cryptography+with+dim+coherent+states&rft.volume=169&rft.issue=1&rft.pages=103-108&rft.date=1999-10-01&rft.issn=0030-4018&rft_id=info%3Adoi%2F10.1016%2FS0030-4018%2899%2900419-8&rft_id=info%3Abibcode%2F1999OptCo.169..103D&rft.aulast=Du%C5%A1ek&rft.aufirst=Miloslav&rft.au=Haderka%2C+Ond%C5%99ej&rft.au=Hendrych%2C+Martin&rft_id=https%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0030401899004198&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-32">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBennettBrassardBreidbart2014" class="citation journal cs1">Bennett, Charles; Brassard, Giles; Breidbart, Seth (2014). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4224740">"Quantum Cryptography II: How to re-use a one-time pad safely even if P=NP"</a>. <i>Natural Computing</i>. <b>13</b> (4): 453–458. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs11047-014-9453-6">10.1007/s11047-014-9453-6</a>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4224740">4224740</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/25400534">25400534</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:3121156">3121156</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Natural+Computing&rft.atitle=Quantum+Cryptography+II%3A+How+to+re-use+a+one-time+pad+safely+even+if+P%3DNP&rft.volume=13&rft.issue=4&rft.pages=453-458&rft.date=2014&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4224740%23id-name%3DPMC&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A3121156%23id-name%3DS2CID&rft_id=info%3Apmid%2F25400534&rft_id=info%3Adoi%2F10.1007%2Fs11047-014-9453-6&rft.aulast=Bennett&rft.aufirst=Charles&rft.au=Brassard%2C+Giles&rft.au=Breidbart%2C+Seth&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4224740&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span> Note: This is also a reprint of the original 1982 paper.</span> </li> <li id="cite_note-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-33">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKahn1996" class="citation book cs1"><a href="/wiki/David_Kahn_(writer)" title="David Kahn (writer)">Kahn, David</a> (1996). <a href="/wiki/The_Codebreakers" title="The Codebreakers"><i>The Codebreakers</i></a>. <a href="/wiki/Macmillan_Publishers_(United_States)" class="mw-redirect" title="Macmillan Publishers (United States)">Macmillan</a>. pp. 402–3. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-684-83130-5" title="Special:BookSources/978-0-684-83130-5"><bdi>978-0-684-83130-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Codebreakers&rft.pages=402-3&rft.pub=Macmillan&rft.date=1996&rft.isbn=978-0-684-83130-5&rft.aulast=Kahn&rft.aufirst=David&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-Sprach_Machine-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-Sprach_Machine_34-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20150313143905/http://www.numbers-stations.com/sprach-machine">"Stasi Sprach Morse Machine"</a>. The Numbers Stations Research and Information Center. Archived from <a rel="nofollow" class="external text" href="http://www.numbers-stations.com/sprach-machine">the original</a> on March 13, 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">March 1,</span> 2015</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=Stasi+Sprach+Morse+Machine&rft_id=http%3A%2F%2Fwww.numbers-stations.com%2Fsprach-machine&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-35">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20190224044402/https://www.nsa.gov/about/cryptologic-heritage/historical-figures-publications/publications/wwii/sigsaly-story/">"National Security Agency | Central Security Service > About Us > Cryptologic Heritage > Historical Figures and Publications > Publications > WWII > Sigsaly Story"</a>. 2019-02-24. Archived from <a rel="nofollow" class="external text" href="https://www.nsa.gov/about/cryptologic-heritage/historical-figures-publications/publications/wwii/sigsaly-story/">the original</a> on 2019-02-24<span class="reference-accessdate">. Retrieved <span class="nowrap">2022-03-27</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=National+Security+Agency+%7C+Central+Security+Service+%3E+About+Us+%3E+Cryptologic+Heritage+%3E+Historical+Figures+and+Publications+%3E+Publications+%3E+WWII+%3E+Sigsaly+Story&rft.date=2019-02-24&rft_id=https%3A%2F%2Fwww.nsa.gov%2Fabout%2Fcryptologic-heritage%2Fhistorical-figures-publications%2Fpublications%2Fwwii%2Fsigsaly-story%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-36"><span class="mw-cite-backlink"><b><a href="#cite_ref-36">^</a></b></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKahn1967" class="citation book cs1"><a href="/wiki/David_Kahn_(writer)" title="David Kahn (writer)">Kahn, David</a> (1967). <a href="/wiki/The_Codebreakers" title="The Codebreakers"><i>The Codebreakers</i></a>. <a href="/wiki/Macmillan_Publishers_(United_States)" class="mw-redirect" title="Macmillan Publishers (United States)">Macmillan</a>. pp. 715 ff. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-684-83130-5" title="Special:BookSources/978-0-684-83130-5"><bdi>978-0-684-83130-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Codebreakers&rft.pages=715+ff&rft.pub=Macmillan&rft.date=1967&rft.isbn=978-0-684-83130-5&rft.aulast=Kahn&rft.aufirst=David&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-37">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHieu2007" class="citation journal cs1">Hieu, Phan Duong (April 2007). <a rel="nofollow" class="external text" href="https://eprint.iacr.org/2016/1136.pdf">"Cryptology during the French and American Wars in Vietnam"</a> <span class="cs1-format">(PDF)</span>. <i>Cryptologia</i>. <b>41</b> (6): 1–21. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F01611194.2017.1292825">10.1080/01611194.2017.1292825</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:3780267">3780267</a><span class="reference-accessdate">. Retrieved <span class="nowrap">14 April</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Cryptologia&rft.atitle=Cryptology+during+the+French+and+American+Wars+in+Vietnam&rft.volume=41&rft.issue=6&rft.pages=1-21&rft.date=2007-04&rft_id=info%3Adoi%2F10.1080%2F01611194.2017.1292825&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A3780267%23id-name%3DS2CID&rft.aulast=Hieu&rft.aufirst=Phan+Duong&rft_id=https%3A%2F%2Feprint.iacr.org%2F2016%2F1136.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-38">^</a></b></span> <span class="reference-text">"<a rel="nofollow" class="external text" href="http://www.radionetherlandsarchives.org/operation-vula-a-secret-dutch-network-against-apartheid/">Operation Vula: a secret Dutch network against apartheid</a>", Radio Netherlands Archives, September 9, 1999</span> </li> <li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJenkin1995" class="citation journal cs1">Jenkin, Tim (May–October 1995). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140826115901/http://www.anc.org.za/show.php?id=4693">"Talking to Vula: The Story of the Secret Underground Communications Network of Operation Vula"</a>. <i>Mayibuye</i>. Archived from <a rel="nofollow" class="external text" href="http://www.anc.org.za/show.php?id=4693">the original</a> on 2014-08-26<span class="reference-accessdate">. Retrieved <span class="nowrap">24 August</span> 2014</span>. <q>Our system was based on the one-time pad, though instead of having paper pads the random numbers were on a disk.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Mayibuye&rft.atitle=Talking+to+Vula%3A+The+Story+of+the+Secret+Underground+Communications+Network+of+Operation+Vula&rft.date=1995-05%2F1995-10&rft.aulast=Jenkin&rft.aufirst=Tim&rft_id=http%3A%2F%2Fwww.anc.org.za%2Fshow.php%3Fid%3D4693&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPidgeon2003" class="citation book cs1">Pidgeon, Geoffrey (2003). "Chapter 28: Bill Miller – Tea with the Germans". <i>The Secret Wireless War – The story of MI6 Communications 1939-1945</i>. UPSO Ltd. p. 249. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-84375-252-3" title="Special:BookSources/978-1-84375-252-3"><bdi>978-1-84375-252-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Chapter+28%3A+Bill+Miller+%E2%80%93+Tea+with+the+Germans&rft.btitle=The+Secret+Wireless+War+%E2%80%93+The+story+of+MI6+Communications+1939-1945&rft.pages=249&rft.pub=UPSO+Ltd&rft.date=2003&rft.isbn=978-1-84375-252-3&rft.aulast=Pidgeon&rft.aufirst=Geoffrey&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJohnson" class="citation web cs1">Johnson, Tim. <a rel="nofollow" class="external text" href="https://www.wausaudailyherald.com/story/sports/high-school/baseball/2018/04/24/what-do-all-those-hand-signals-mean-inside-hidden-language-baseball-and-softball/534843002/">"What do all those hand signals mean? Inside the hidden language of baseball and softball"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">14 June</span> 2024</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=What+do+all+those+hand+signals+mean%3F+Inside+the+hidden+language+of+baseball+and+softball&rft.aulast=Johnson&rft.aufirst=Tim&rft_id=https%3A%2F%2Fwww.wausaudailyherald.com%2Fstory%2Fsports%2Fhigh-school%2Fbaseball%2F2018%2F04%2F24%2Fwhat-do-all-those-hand-signals-mean-inside-hidden-language-baseball-and-softball%2F534843002%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-boaklectures1-42"><span class="mw-cite-backlink">^ <a href="#cite_ref-boaklectures1_42-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-boaklectures1_42-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-boaklectures1_42-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-boaklectures1_42-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBoak1973" class="citation book cs1">Boak, David G. (July 1973) [1966]. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170525181251/http://www.governmentattic.org/18docs/Hist_US_COMSEC_Boak_NSA_1973u.pdf"><i>A History of U.S. Communications Security; the David G. Boak Lectures, Vol. I</i></a> <span class="cs1-format">(PDF)</span> (2015 declassification review ed.). Ft. George G. Meade, MD: U.S. National Security Agency. Archived from <a rel="nofollow" class="external text" href="https://www.governmentattic.org/18docs/Hist_US_COMSEC_Boak_NSA_1973u.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 2017-05-25<span class="reference-accessdate">. Retrieved <span class="nowrap">2017-04-23</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+History+of+U.S.+Communications+Security%3B+the+David+G.+Boak+Lectures%2C+Vol.+I&rft.place=Ft.+George+G.+Meade%2C+MD&rft.edition=2015+declassification+review&rft.pub=U.S.+National+Security+Agency&rft.date=1973-07&rft.aulast=Boak&rft.aufirst=David+G.&rft_id=https%3A%2F%2Fwww.governmentattic.org%2F18docs%2FHist_US_COMSEC_Boak_NSA_1973u.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-43">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKlein2003" class="citation web cs1">Klein, Melville (2003). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20060213165531/http://www.nsa.gov/publications/publi00017.pdf">"Securing Record Communications: The TSEC/KW-26"</a> <span class="cs1-format">(PDF)</span>. NSA. Archived from <a rel="nofollow" class="external text" href="http://www.nsa.gov/publications/publi00017.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 2006-02-13<span class="reference-accessdate">. Retrieved <span class="nowrap">2006-05-12</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Securing+Record+Communications%3A+The+TSEC%2FKW-26&rft.pub=NSA&rft.date=2003&rft.aulast=Klein&rft.aufirst=Melville&rft_id=http%3A%2F%2Fwww.nsa.gov%2Fpublications%2Fpubli00017.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></span> </li> <li id="cite_note-44"><span class="mw-cite-backlink"><b><a href="#cite_ref-44">^</a></b></span> <span class="reference-text">Erskine, Ralph, "Enigma's Security: What the Germans Really Knew", in <i>Action this Day</i>, edited by Ralph Erskine and Michael Smith, pp. 370–386, 2001.</span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=19" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239549316">.mw-parser-output .refbegin{margin-bottom:0.5em}.mw-parser-output .refbegin-hanging-indents>ul{margin-left:0}.mw-parser-output .refbegin-hanging-indents>ul>li{margin-left:0;padding-left:3.2em;text-indent:-3.2em}.mw-parser-output .refbegin-hanging-indents ul,.mw-parser-output .refbegin-hanging-indents ul li{list-style:none}@media(max-width:720px){.mw-parser-output .refbegin-hanging-indents>ul>li{padding-left:1.6em;text-indent:-1.6em}}.mw-parser-output .refbegin-columns{margin-top:0.3em}.mw-parser-output .refbegin-columns ul{margin-top:0}.mw-parser-output .refbegin-columns li{page-break-inside:avoid;break-inside:avoid-column}@media screen{.mw-parser-output .refbegin{font-size:90%}}</style><div class="refbegin" style=""> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRubina1996" class="citation journal cs1">Rubina, Frank (1996). "One-Time Pad cryptography". <i>Cryptologia</i>. <b>20</b> (4): 359–364. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F0161-119691885040">10.1080/0161-119691885040</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0161-1194">0161-1194</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Cryptologia&rft.atitle=One-Time+Pad+cryptography&rft.volume=20&rft.issue=4&rft.pages=359-364&rft.date=1996&rft_id=info%3Adoi%2F10.1080%2F0161-119691885040&rft.issn=0161-1194&rft.aulast=Rubina&rft.aufirst=Frank&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFostera1997" class="citation journal cs1">Fostera, Caxton C. (1997). "Drawbacks of the One-time Pad". <i>Cryptologia</i>. <b>21</b> (4): 350–352. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F0161-119791885986">10.1080/0161-119791885986</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0161-1194">0161-1194</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Cryptologia&rft.atitle=Drawbacks+of+the+One-time+Pad&rft.volume=21&rft.issue=4&rft.pages=350-352&rft.date=1997&rft_id=info%3Adoi%2F10.1080%2F0161-119791885986&rft.issn=0161-1194&rft.aulast=Fostera&rft.aufirst=Caxton+C.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOne-time+pad" class="Z3988"></span></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=One-time_pad&action=edit&section=20" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>Detailed <a rel="nofollow" class="external text" href="https://www.ciphermachinesandcryptology.com/en/onetimepad.htm">description and history of One-time Pad</a> with examples and images on <a rel="nofollow" class="external text" href="https://www.ciphermachinesandcryptology.com">Cipher Machines and Cryptology</a></li> <li>The <a href="/wiki/FreeS/WAN" title="FreeS/WAN">FreeS/WAN</a> <a rel="nofollow" class="external text" href="http://www.freeswan.org/freeswan_trees/freeswan-2.06/doc/glossary.html#OTP">glossary entry</a> with a discussion of OTP weaknesses</li></ul> <div style="clear:both;" class=""></div> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist 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class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Cryptography_classical" title="Template:Cryptography classical"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Cryptography_classical" title="Template talk:Cryptography classical"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Cryptography_classical" title="Special:EditPage/Template:Cryptography classical"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Classical_cryptography" style="font-size:114%;margin:0 4em"><a href="/wiki/Classical_cipher" title="Classical cipher">Classical cryptography</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Cipher" title="Cipher">Ciphers</a><br />by family</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Polyalphabetic_cipher" title="Polyalphabetic cipher">Polyalphabetic</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alberti_cipher" title="Alberti cipher">Alberti</a></li> <li><a href="/wiki/Enigma_machine" title="Enigma machine">Enigma</a></li> <li><a href="/wiki/Trithemius_cipher" class="mw-redirect" title="Trithemius cipher">Trithemius</a></li> <li><a href="/wiki/Vigen%C3%A8re_cipher" title="Vigenère cipher">Vigenère</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Polybius_square" title="Polybius square">Polybius square</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ADFGVX_cipher" title="ADFGVX cipher">ADFGVX</a></li> <li><a href="/wiki/Bifid_cipher" title="Bifid cipher">Bifid</a></li> <li><a href="/wiki/Nihilist_cipher" title="Nihilist cipher">Nihilist</a></li> <li><a href="/wiki/Tap_code" title="Tap code">Tap code</a></li> <li><a href="/wiki/Trifid_cipher" title="Trifid cipher">Trifid</a></li> <li><a href="/wiki/VIC_cipher" title="VIC cipher">VIC cipher</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;">Square</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Playfair_cipher" title="Playfair cipher">Playfair</a></li> <li><a href="/wiki/Two-square_cipher" title="Two-square cipher">Two-square</a></li> <li><a href="/wiki/Four-square_cipher" title="Four-square cipher">Four-square</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Substitution_cipher" title="Substitution cipher">Substitution</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Affine_cipher" title="Affine cipher">Affine</a></li> <li><a href="/wiki/Atbash" title="Atbash">Atbash</a></li> <li><a href="/wiki/Autokey_cipher" title="Autokey cipher">Autokey</a></li> <li><a href="/wiki/Beaufort_cipher" title="Beaufort cipher">Beaufort</a></li> <li><a href="/wiki/Caesar_cipher" title="Caesar cipher">Caesar</a></li> <li><a href="/wiki/Chaocipher" title="Chaocipher">Chaocipher</a></li> <li><a href="/wiki/Great_Cipher" title="Great Cipher">Great</a></li> <li><a href="/wiki/Hill_cipher" title="Hill cipher">Hill</a></li> <li><a href="/wiki/Pigpen_cipher" title="Pigpen cipher">Pigpen</a></li> <li><a href="/wiki/ROT13" title="ROT13">ROT13</a></li> <li><a href="/wiki/Running_key_cipher" title="Running key cipher">Running key</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;"><a href="/wiki/Transposition_cipher" title="Transposition cipher">Transposition</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Transposition_cipher#Columnar_transposition" title="Transposition cipher">Columnar</a></li> <li><a href="/wiki/Transposition_cipher#Double_transposition" title="Transposition cipher">Double</a></li> <li><a href="/wiki/Transposition_cipher#Myszkowski_transposition" title="Transposition cipher">Myszkowski</a></li> <li><a href="/wiki/Rail_fence_cipher" title="Rail fence cipher">Rail fence</a></li> <li><a href="/wiki/Transposition_cipher#Route_cipher" title="Transposition cipher">Route</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;">Other</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BATCO" title="BATCO">BATCO</a></li> <li><a href="/wiki/DRYAD" title="DRYAD">DRYAD</a></li> <li><a href="/wiki/Mlecchita_vikalpa" title="Mlecchita vikalpa">Kama Sutra</a></li> <li><a class="mw-selflink selflink">One-time pad</a></li> <li><a href="/wiki/Rasterschl%C3%BCssel_44" title="Rasterschlüssel 44">Rasterschlüssel 44</a></li> <li><a href="/wiki/Reihenschieber" title="Reihenschieber">Reihenschieber</a></li> <li><a href="/wiki/Reservehandverfahren" title="Reservehandverfahren">Reservehandverfahren</a></li> <li><a href="/wiki/Slidex" title="Slidex">Slidex</a></li> <li><a href="/wiki/Solitaire_(cipher)" title="Solitaire (cipher)">Solitaire</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Code_(cryptography)" title="Code (cryptography)">Codes</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Book_cipher" title="Book cipher">Book</a></li> <li><a href="/wiki/Code_talker" title="Code talker">Code talker</a></li> <li><a href="/wiki/Poem_code" title="Poem code">Poem</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Steganography" title="Steganography">Steganography</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bacon%27s_cipher" title="Bacon's cipher">Bacon</a></li> <li><a href="/wiki/Grille_(cryptography)" title="Grille (cryptography)">Grille</a></li> <li><a href="/wiki/Null_cipher" title="Null cipher">Null</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Cryptanalysis</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cryptogram" title="Cryptogram">Cryptogram</a></li> <li><a href="/wiki/Frequency_analysis" title="Frequency analysis">Frequency analysis</a></li> <li><a href="/wiki/Index_of_coincidence" title="Index of coincidence">Index of coincidence</a> (Units: <a href="/wiki/Hartley_(unit)" title="Hartley (unit)">Ban</a> and <a href="/wiki/Nat_(unit)" title="Nat (unit)">Nat</a>)</li> <li><a href="/wiki/Information_leakage" title="Information leakage">Information leakage</a></li> <li><a href="/wiki/Kasiski_examination" title="Kasiski examination">Kasiski examination</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible mw-collapsed navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Cryptography_navbox" title="Template:Cryptography navbox"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Cryptography_navbox" title="Template talk:Cryptography navbox"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Cryptography_navbox" title="Special:EditPage/Template:Cryptography navbox"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Cryptography" style="font-size:114%;margin:0 4em"><a href="/wiki/Cryptography" title="Cryptography">Cryptography</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">General</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/History_of_cryptography" title="History of cryptography">History of cryptography</a></li> <li><a href="/wiki/Outline_of_cryptography" title="Outline of cryptography">Outline of cryptography</a></li> <li><a href="/wiki/Classical_cipher" title="Classical cipher">Classical cipher</a></li> <li><a href="/wiki/Cryptographic_protocol" title="Cryptographic protocol">Cryptographic protocol</a> <ul><li><a href="/wiki/Authentication_protocol" title="Authentication protocol">Authentication protocol</a></li></ul></li> <li><a href="/wiki/Cryptographic_primitive" title="Cryptographic primitive">Cryptographic primitive</a></li> <li><a href="/wiki/Cryptanalysis" title="Cryptanalysis">Cryptanalysis</a></li> <li><a href="/wiki/Cryptocurrency" title="Cryptocurrency">Cryptocurrency</a></li> <li><a href="/wiki/Cryptosystem" title="Cryptosystem">Cryptosystem</a></li> <li><a href="/wiki/Cryptographic_nonce" title="Cryptographic nonce">Cryptographic nonce</a></li> <li><a href="/wiki/Cryptovirology" title="Cryptovirology">Cryptovirology</a></li> <li><a href="/wiki/Hash_function" title="Hash function">Hash function</a> <ul><li><a href="/wiki/Cryptographic_hash_function" title="Cryptographic hash function">Cryptographic hash function</a></li> <li><a href="/wiki/Key_derivation_function" title="Key derivation function">Key derivation function</a></li> <li><a href="/wiki/Secure_Hash_Algorithms" title="Secure Hash Algorithms">Secure Hash Algorithms</a></li></ul></li> <li><a href="/wiki/Digital_signature" title="Digital signature">Digital signature</a></li> <li><a href="/wiki/Kleptography" title="Kleptography">Kleptography</a></li> <li><a href="/wiki/Key_(cryptography)" title="Key (cryptography)">Key (cryptography)</a></li> <li><a href="/wiki/Key_exchange" title="Key exchange">Key exchange</a></li> <li><a href="/wiki/Key_generator" title="Key generator">Key generator</a></li> <li><a href="/wiki/Key_schedule" title="Key schedule">Key schedule</a></li> <li><a href="/wiki/Key_stretching" title="Key stretching">Key stretching</a></li> <li><a href="/wiki/Keygen" title="Keygen">Keygen</a></li> <li><a href="/wiki/Template:Cryptography_machines" title="Template:Cryptography machines">Machines</a></li> <li><a href="/wiki/Cryptojacking_malware" class="mw-redirect" title="Cryptojacking malware">Cryptojacking malware</a></li> <li><a href="/wiki/Ransomware" title="Ransomware">Ransomware</a></li> <li><a href="/wiki/Random_number_generation" title="Random number generation">Random number generation</a> <ul><li><a href="/wiki/Cryptographically_secure_pseudorandom_number_generator" title="Cryptographically secure pseudorandom number generator">Cryptographically secure pseudorandom number generator</a> (CSPRNG)</li></ul></li> <li><a href="/wiki/Pseudorandom_noise" title="Pseudorandom noise">Pseudorandom noise</a> (PRN)</li> <li><a href="/wiki/Secure_channel" title="Secure channel">Secure channel</a></li> <li><a href="/wiki/Insecure_channel" class="mw-redirect" title="Insecure channel">Insecure channel</a></li> <li><a href="/wiki/Subliminal_channel" title="Subliminal channel">Subliminal channel</a></li> <li><a href="/wiki/Encryption" title="Encryption">Encryption</a></li> <li><a href="/wiki/Decryption" class="mw-redirect" title="Decryption">Decryption</a></li> <li><a href="/wiki/End-to-end_encryption" title="End-to-end encryption">End-to-end encryption</a></li> <li><a href="/wiki/Harvest_now,_decrypt_later" title="Harvest now, decrypt later">Harvest now, decrypt later</a></li> <li><a href="/wiki/Information-theoretic_security" title="Information-theoretic security">Information-theoretic security</a></li> <li><a href="/wiki/Plaintext" title="Plaintext">Plaintext</a></li> <li><a href="/wiki/Codetext" class="mw-redirect" title="Codetext">Codetext</a></li> <li><a href="/wiki/Ciphertext" title="Ciphertext">Ciphertext</a></li> <li><a href="/wiki/Shared_secret" title="Shared secret">Shared secret</a></li> <li><a href="/wiki/Trapdoor_function" title="Trapdoor function">Trapdoor function</a></li> <li><a href="/wiki/Trusted_timestamping" title="Trusted timestamping">Trusted timestamping</a></li> <li><a href="/wiki/Key-based_routing" title="Key-based routing">Key-based routing</a></li> <li><a href="/wiki/Onion_routing" title="Onion routing">Onion routing</a></li> <li><a href="/wiki/Garlic_routing" title="Garlic routing">Garlic routing</a></li> <li><a href="/wiki/Kademlia" title="Kademlia">Kademlia</a></li> <li><a href="/wiki/Mix_network" title="Mix network">Mix network</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Mathematics</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cryptographic_hash_function" title="Cryptographic hash function">Cryptographic hash function</a></li> <li><a href="/wiki/Block_cipher" title="Block cipher">Block cipher</a></li> <li><a href="/wiki/Stream_cipher" title="Stream cipher">Stream cipher</a></li> <li><a href="/wiki/Symmetric-key_algorithm" title="Symmetric-key algorithm">Symmetric-key algorithm</a></li> <li><a href="/wiki/Authenticated_encryption" title="Authenticated encryption">Authenticated encryption</a></li> <li><a href="/wiki/Public-key_cryptography" title="Public-key cryptography">Public-key cryptography</a></li> <li><a href="/wiki/Quantum_key_distribution" title="Quantum key distribution">Quantum key distribution</a></li> <li><a href="/wiki/Quantum_cryptography" title="Quantum cryptography">Quantum cryptography</a></li> <li><a href="/wiki/Post-quantum_cryptography" title="Post-quantum cryptography">Post-quantum cryptography</a></li> <li><a href="/wiki/Message_authentication_code" title="Message authentication code">Message authentication code</a></li> <li><a href="/wiki/Cryptographically_secure_pseudorandom_number_generator" title="Cryptographically secure pseudorandom number generator">Random numbers</a></li> <li><a href="/wiki/Steganography" title="Steganography">Steganography</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, 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