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<span>Classification</span> </div> </a> <ul id="toc-Classification-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Trusted_(digital)_timestamping" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Trusted_(digital)_timestamping"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Trusted (digital) timestamping</span> </div> </a> <ul id="toc-Trusted_(digital)_timestamping-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Creating_a_timestamp" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Creating_a_timestamp"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Creating a timestamp</span> </div> </a> <ul id="toc-Creating_a_timestamp-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Checking_the_timestamp" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Checking_the_timestamp"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Checking the timestamp</span> </div> </a> <ul id="toc-Checking_the_timestamp-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Decentralized_timestamping_on_the_blockchain" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Decentralized_timestamping_on_the_blockchain"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Decentralized timestamping on the blockchain</span> </div> </a> <ul id="toc-Decentralized_timestamping_on_the_blockchain-sublist" class="vector-toc-list"> </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">7</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" 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Security here means that no one—not even the owner of the document—should be able to change it once it has been recorded provided that the timestamper's integrity is never compromised. </p><p>The administrative aspect involves setting up a publicly available, trusted timestamp management infrastructure to collect, process and renew timestamps. </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=Trusted_timestamping&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The idea of timestamping information is centuries old. For example, when <a href="/wiki/Robert_Hooke" title="Robert Hooke">Robert Hooke</a> discovered <a href="/wiki/Hooke%27s_law" title="Hooke's law">Hooke's law</a> in 1660, he did not want to publish it yet, but wanted to be able to claim priority. So he published the <a href="/wiki/Anagram" title="Anagram">anagram</a> <i>ceiiinosssttuv</i> and later published the translation <i>ut tensio sic vis</i> (Latin for "as is the extension, so is the force"). Similarly, <a href="/wiki/Galileo_Galilei" title="Galileo Galilei">Galileo</a> first published his discovery of the phases of Venus in the anagram form. </p><p><a href="/wiki/Sir_Isaac_Newton" class="mw-redirect" title="Sir Isaac Newton">Sir Isaac Newton</a>, in responding to questions from <a href="/wiki/Gottfried_Wilhelm_Leibniz" title="Gottfried Wilhelm Leibniz">Leibniz</a> in a letter in 1677, concealed the details of his <a href="/wiki/History_of_calculus#Newton" title="History of calculus">"fluxional technique"</a> with an anagram: </p> <dl><dd><i>The foundations of these operations is evident enough, in fact; but because I cannot proceed with the explanation of it now, I have preferred to conceal it thus: 6accdae13eff7i3l9n4o4qrr4s8t12ux. On this foundation I have also tried to simplify the theories which concern the squaring of curves, and I have arrived at certain general Theorems.</i></dd></dl> <p>Trusted digital timestamping has first been discussed in literature by <a href="/wiki/Stuart_Haber" title="Stuart Haber">Stuart Haber</a> and <a href="/wiki/W._Scott_Stornetta" title="W. Scott Stornetta">W. Scott Stornetta</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> <div class="mw-heading mw-heading2"><h2 id="Classification">Classification</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Trusted_timestamping&action=edit&section=2" title="Edit section: Classification"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>There are many timestamping schemes with different security goals: </p> <ul><li><a href="/wiki/Public_key_infrastructure" title="Public key infrastructure">PKI</a>-based – timestamp token is protected using PKI <a href="/wiki/Digital_signature" title="Digital signature">digital signature</a>.</li> <li><a href="/wiki/Linked_timestamping" title="Linked timestamping">Linking-based schemes</a> – timestamp is generated in such a way that it is related to other timestamps.</li> <li>Distributed schemes – timestamp is generated in cooperation of multiple parties.</li> <li><a href="/wiki/Transient-key_cryptography" title="Transient-key cryptography">Transient key</a> scheme – variant of PKI with short-living signing keys.</li> <li><a href="/wiki/Message_authentication_code" title="Message authentication code">MAC</a> – simple secret key-based scheme, found in <a href="/wiki/ANSI_ASC_X9.95_Standard" title="ANSI ASC X9.95 Standard">ANSI ASC X9.95 Standard</a>.</li> <li>Database – document hashes are stored in trusted archive; there is online lookup service for verification.</li> <li>Hybrid schemes – the linked and signed method is prevailing, see <a href="/wiki/ANSI_ASC_X9.95_Standard" title="ANSI ASC X9.95 Standard">X9.95</a>.</li></ul> <p>Coverage in standards: </p> <table class="wikitable"> <tbody><tr> <th>Scheme </th> <th>RFC 3161 </th> <th><a href="/wiki/ANSI_ASC_X9.95_Standard" title="ANSI ASC X9.95 Standard">X9.95</a> </th> <th><a href="/wiki/ISO/IEC_18014" title="ISO/IEC 18014">ISO/IEC 18014</a> </th></tr> <tr> <td>PKI </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <td>Linked </td> <td> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <td>MAC </td> <td> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td> </td></tr> <tr> <td>Database </td> <td> </td> <td> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <td>Transient key </td> <td> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td> </td></tr> <tr> <td>Linked and signed </td> <td> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td> </td></tr></tbody></table> <p>For systematic classification and evaluation of timestamping schemes see works by Masashi Une.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Trusted_(digital)_timestamping"><span id="Trusted_.28digital.29_timestamping"></span>Trusted (digital) timestamping</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Trusted_timestamping&action=edit&section=3" title="Edit section: Trusted (digital) timestamping"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Trusted_timestamping.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Trusted_timestamping.svg/330px-Trusted_timestamping.svg.png" decoding="async" width="330" height="201" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Trusted_timestamping.svg/495px-Trusted_timestamping.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Trusted_timestamping.svg/660px-Trusted_timestamping.svg.png 2x" data-file-width="1015" data-file-height="617" /></a><figcaption>Getting a timestamp from a trusted third party</figcaption></figure> <p>According to the RFC 3161 standard, a trusted timestamp is a <a href="/wiki/Timestamp" title="Timestamp">timestamp</a> issued by a <a href="/wiki/Trusted_Third_Party" class="mw-redirect" title="Trusted Third Party">Trusted Third Party</a> (TTP) acting as a <b>Time Stamping Authority</b> (<b>TSA</b>). It is used to prove the existence of certain data before a certain point (e.g. contracts, research data, medical records, ...) without the possibility that the owner can backdate the timestamps. Multiple TSAs can be used to increase reliability and reduce vulnerability. </p><p>The newer <a href="/wiki/ANSI_ASC_X9.95_Standard" title="ANSI ASC X9.95 Standard">ANSI ASC X9.95 Standard</a> for <a href="/wiki/Timestamp" title="Timestamp">trusted timestamps</a> augments the RFC 3161 standard with data-level security requirements to ensure <a href="/wiki/Data_integrity" title="Data integrity">data integrity</a> against a reliable time source that is provable to any third party. This standard has been applied to authenticating digitally signed data for regulatory compliance, financial transactions, and legal evidence. </p> <div class="mw-heading mw-heading2"><h2 id="Creating_a_timestamp">Creating a timestamp</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Trusted_timestamping&action=edit&section=4" title="Edit section: Creating a timestamp"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The technique is based on <a href="/wiki/Digital_signatures" class="mw-redirect" title="Digital signatures">digital signatures</a> and <a href="/wiki/Hash_functions" class="mw-redirect" title="Hash functions">hash functions</a>. First a hash is calculated from the data. A hash is a sort of digital fingerprint of the original data: a string of bits that is practically impossible to duplicate with any other set of data. If the original data is changed then this will result in a completely different hash. This hash is sent to the TSA. The TSA concatenates a timestamp to the hash and calculates the hash of this concatenation. This hash is in turn <a href="/wiki/Digital_signature" title="Digital signature">digitally signed</a> with the <a href="/wiki/Private_key" class="mw-redirect" title="Private key">private key</a> of the TSA. This signed hash + the timestamp is sent back to the requester of the timestamp who stores these with the original data (see diagram). </p><p>Since the original data cannot be calculated from the hash (because the <a href="/wiki/Hash_function" title="Hash function">hash function</a> is a <a href="/wiki/One_way_function" class="mw-redirect" title="One way function">one way function</a>), the TSA never gets to see the original data, which allows the use of this method for confidential data. </p> <div class="mw-heading mw-heading2"><h2 id="Checking_the_timestamp">Checking the timestamp</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Trusted_timestamping&action=edit&section=5" title="Edit section: Checking the timestamp"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Checking_timestamp.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Checking_timestamp.svg/330px-Checking_timestamp.svg.png" decoding="async" width="330" height="193" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Checking_timestamp.svg/495px-Checking_timestamp.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Checking_timestamp.svg/660px-Checking_timestamp.svg.png 2x" data-file-width="1610" data-file-height="941" /></a><figcaption>Checking correctness of a timestamp generated by a time stamping authority (TSA)</figcaption></figure> <p>Anyone trusting the timestamper can then verify that the document was <i>not</i> created <i>after</i> the date that the timestamper vouches. It can also no longer be repudiated that the requester of the timestamp was in possession of the original data at the time given by the timestamp. To prove this (see diagram) the <a href="/wiki/Cryptographic_hash_function" title="Cryptographic hash function">hash</a> of the original data is calculated, the timestamp given by the TSA is appended to it and the hash of the result of this concatenation is calculated, call this hash A. </p><p>Then the <a href="/wiki/Digital_signature" title="Digital signature">digital signature</a> of the TSA needs to be validated. This is done by decrypting the digital signature using public key of TSA, producing hash B. Hash A is then compared with hash B inside the signed TSA message to confirm they are equal, proving that the timestamp and message is unaltered and was issued by the TSA. If not, then either the timestamp was altered or the timestamp was not issued by the TSA. </p> <div class="mw-heading mw-heading2"><h2 id="Decentralized_timestamping_on_the_blockchain">Decentralized timestamping on the blockchain</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Trusted_timestamping&action=edit&section=6" title="Edit section: Decentralized timestamping on the blockchain"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>With the advent of cryptocurrencies like <a href="/wiki/Bitcoin" title="Bitcoin">bitcoin</a>, it has become possible to get some level of secure timestamp accuracy in a <a href="/wiki/Decentralized_computing" title="Decentralized computing">decentralized</a> and tamper-proof manner. Digital data can be hashed and the hash can be incorporated into a transaction stored in the <a href="/wiki/Blockchain_(database)" class="mw-redirect" title="Blockchain (database)">blockchain</a>, which serves as evidence of the time at which that data existed.<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><sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> For <a href="/wiki/Proof_of_work" title="Proof of work">proof of work</a> blockchains, the security derives from the tremendous amount of computational effort performed after the hash was submitted to the blockchain. Tampering with the timestamp would require more computational resources than the rest of the network combined, and cannot be done unnoticed in an actively defended blockchain. </p><p>However, the design and implementation of Bitcoin in particular makes its timestamps vulnerable to some degree of manipulation, allowing timestamps up to two hours in the future, and accepting new blocks with timestamps earlier than the previous block.<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> </p><p>The decentralized timestamping approach using the blockchain has also found applications in other areas, such as in <a href="/wiki/Dashcam" title="Dashcam">dashboard cameras</a>, to secure the integrity of video files at the time of their recording,<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> or to prove priority for creative content and ideas shared on social media platforms.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p> <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=Trusted_timestamping&action=edit&section=7" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Timestamp" title="Timestamp">Timestamp</a></li> <li><a href="/wiki/Timestamping_(computing)" title="Timestamping (computing)">Timestamping (computing)</a></li> <li><a href="/wiki/Certificate_Transparency" title="Certificate Transparency">Certificate Transparency</a></li> <li><a href="/wiki/Cryptography" title="Cryptography">Cryptography</a></li> <li><a href="/wiki/Computer_security" title="Computer security">Computer security</a></li> <li><a href="/wiki/Digital_signature" title="Digital signature">Digital signature</a></li> <li><a href="/wiki/Digital_Postmarks" title="Digital Postmarks">Digital Postmarks</a></li> <li><a href="/wiki/Smart_contract" title="Smart contract">Smart contract</a></li> <li><a href="/wiki/CAdES_(computing)" title="CAdES (computing)">CAdES – CMS Advanced Electronic Signature</a></li> <li><a href="/wiki/PAdES" title="PAdES">PAdES – PDF Advanced Electronic Signature</a></li> <li><a href="/wiki/XAdES" title="XAdES">XAdES – XML Advanced Electronic Signature</a></li></ul> <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=Trusted_timestamping&action=edit&section=8" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-references-wrap"><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="CITEREFHaberStornetta1991" class="citation journal cs1">Haber, S.; Stornetta, W. S. (1991). <a rel="nofollow" class="external text" href="https://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.46.8740&rank=1">"How to time-stamp a digital document"</a>. <i>Journal of Cryptology</i>. <b>3</b> (2): 99–111. <a href="/wiki/CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.46.8740">10.1.1.46.8740</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/10.1007%2FBF00196791">10.1007/BF00196791</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:14363020">14363020</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Cryptology&rft.atitle=How+to+time-stamp+a+digital+document&rft.volume=3&rft.issue=2&rft.pages=99-111&rft.date=1991&rft_id=https%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fsummary%3Fdoi%3D10.1.1.46.8740%23id-name%3DCiteSeerX&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A14363020%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1007%2FBF00196791&rft.aulast=Haber&rft.aufirst=S.&rft.au=Stornetta%2C+W.+S.&rft_id=https%3A%2F%2Fciteseer.ist.psu.edu%2Fviewdoc%2Fsummary%3Fdoi%3D10.1.1.46.8740%26rank%3D1&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATrusted+timestamping" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFUne2001" class="citation journal cs1">Une, Masashi (2001). <a rel="nofollow" class="external text" href="https://www.imes.boj.or.jp/research/papers/english/01-E-18.pdf">"The Security Evaluation of Time Stamping Schemes: The Present Situation and Studies"</a> <span class="cs1-format">(PDF)</span>. <i>IMES Discussion Papers Series</i>. Institute for Monetary and Economic Studies, Bank of Japan. 2001-E-18.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=IMES+Discussion+Papers+Series&rft.atitle=The+Security+Evaluation+of+Time+Stamping+Schemes%3A+The+Present+Situation+and+Studies&rft.date=2001&rft.aulast=Une&rft.aufirst=Masashi&rft_id=https%3A%2F%2Fwww.imes.boj.or.jp%2Fresearch%2Fpapers%2Fenglish%2F01-E-18.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATrusted+timestamping" 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 id="CITEREFJones2017" class="citation web cs1">Jones, Shawn M. (2017-04-20). <a rel="nofollow" class="external text" href="https://ws-dl.blogspot.de/2017/04/2017-04-20-trusted-timestamping-of.html">"2017-04-20: Trusted Timestamping of Mementos"</a>. <i>ws-dl.blogspot.de</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2017-10-30</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=ws-dl.blogspot.de&rft.atitle=2017-04-20%3A+Trusted+Timestamping+of+Mementos&rft.date=2017-04-20&rft.aulast=Jones&rft.aufirst=Shawn+M.&rft_id=https%3A%2F%2Fws-dl.blogspot.de%2F2017%2F04%2F2017-04-20-trusted-timestamping-of.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATrusted+timestamping" class="Z3988"></span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text">Gipp, B., Meuschke, N. and Gernandt, A., 2015 <a rel="nofollow" class="external text" href="https://www.gipp.com/wp-content/papercite-data/pdf/gipp15a.pdf">"Decentralized Trusted Timestamping using the Crypto Currency Bitcoin."</a> in Proceedings of the iConference 2015. March 2015, Newport Beach, California.</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="CITEREFBoverman2011" class="citation web cs1">Boverman, Alex (2011-05-25). <a rel="nofollow" class="external text" href="http://culubas.blogspot.com/2011/05/timejacking-bitcoin_802.html">"culubas: Timejacking & Bitcoin"</a>. <i>culubas</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2020-05-30</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=culubas&rft.atitle=culubas%3A+Timejacking+%26+Bitcoin&rft.date=2011-05-25&rft.aulast=Boverman&rft.aufirst=Alex&rft_id=http%3A%2F%2Fculubas.blogspot.com%2F2011%2F05%2Ftimejacking-bitcoin_802.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATrusted+timestamping" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text">B. Gipp, J. Kosti, and C. Breitinger. 2016. <a rel="nofollow" class="external text" href="https://www.gipp.com/wp-content/papercite-data/pdf/gipp2016a.pdf">"Securing Video Integrity Using Decentralized Trusted Timestamping on the Blockchain"</a> in Proceedings of the 10th Mediterranean Conference on Information Systems (MCIS), Paphos, Cyprus.</span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text">C. Breitinger, B. Gipp. 2017. <a rel="nofollow" class="external text" href="https://www.gipp.com/wp-content/papercite-data/pdf/breitinger2017.pdf">"VirtualPatent – Enabling the Traceability of Ideas Shared Online using Decentralized Trusted Timestamping"</a> in Proceedings of the 15th International Symposium of Information Science, Berlin, 2017.</span> </li> </ol></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=Trusted_timestamping&action=edit&section=9" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3161">3161</a> Internet X.509 Public Key Infrastructure Time-Stamp Protocol (TSP)</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3628">3628</a> Policy Requirements for Time-Stamping Authorities (TSAs)</li> <li><a rel="nofollow" class="external text" href="http://www.gipp.com/wp-content/papercite-data/pdf/gipp15a.pdf">Decentralized Trusted Timestamping (DTT) using the Crypto Currency Bitcoin</a></li> <li><a rel="nofollow" class="external text" href="http://www.techstreet.com/cgi-bin/detail?product_id=1327239">ANSI ASC X9.95 Standard for Trusted Time Stamps</a></li> <li><a rel="nofollow" class="external text" href="http://www.etsi.org/deliver/etsi_ts/101800_101899/101861/01.04.01_60/ts_101861v010401p.pdf">ETSI TS 101 861 V1.4.1</a> Electronic Signatures and Infrastructures (ESI); Time stamping profile</li> <li><a rel="nofollow" class="external text" href="http://www.etsi.org/deliver/etsi_ts/102000_102099/102023/01.02.02_60/ts_102023v010202p.pdf">ETSI TS 102 023 V1.2.2</a> Electronic Signatures and Infrastructures (ESI); Policy requirements for time-stamping authorities</li> <li><a rel="nofollow" class="external text" href="https://www.sans.org/reading-room/whitepapers/vpns/analysis-secure-time-stamp-device-746">Analysis of a Secure Time Stamp Device</a> (2001) SANS Institute</li> <li><a rel="nofollow" class="external text" href="http://www.csee.umbc.edu/~yzou1/681report.pdf">Implementation of TSP Protocol</a> CMSC 681 Project Report, Youyong Zou</li></ul>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1&useformat=desktop" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Trusted_timestamping&oldid=1257212242">https://en.wikipedia.org/w/index.php?title=Trusted_timestamping&oldid=1257212242</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Time" title="Category:Time">Time</a></li><li><a href="/wiki/Category:Authentication_methods" title="Category:Authentication methods">Authentication methods</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden categories: <ul><li><a href="/wiki/Category:Articles_with_short_description" title="Category:Articles with short description">Articles with short description</a></li><li><a href="/wiki/Category:Short_description_matches_Wikidata" title="Category:Short description matches Wikidata">Short description matches Wikidata</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 13 November 2024, at 20:38<span class="anonymous-show"> (UTC)</span>.</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. 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