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</script><link rel="icon" href="https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=32" sizes="32x32" /> <link rel="icon" href="https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=192" sizes="192x192" /> <link rel="apple-touch-icon" href="https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=180" /> <meta name="msapplication-TileImage" content="https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=270" /> </head> <body class="post-template-default single single-post postid-131 single-format-standard wp-embed-responsive customizer-styles-applied singular has-main-navigation jetpack-reblog-enabled"> <div id="page" class="site"> <a class="skip-link screen-reader-text" href="#content">Skip to content</a> <header id="masthead" class="site-header header_classes has-title-and-tagline has-menu" role="banner"> <div class="site-branding"> <p class="site-title"><a href="https://arthurvandermerwe.com/" rel="home">Cryptography & Payments</a></p> <p class="site-description"> Arthur Van Der Merwe </p> </div> <nav id="site-navigation" class="primary-navigation" role="navigation" aria-label="Main"> <button id="primary-close-menu" class="button close"> <span class="dropdown-icon close">Close <svg class="svg-icon" width="24" height="24" aria-hidden="true" role="img" focusable="false" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg"><path fill-rule="evenodd" clip-rule="evenodd" d="M12 10.9394L5.53033 4.46973L4.46967 5.53039L10.9393 12.0001L4.46967 18.4697L5.53033 19.5304L12 13.0607L18.4697 19.5304L19.5303 18.4697L13.0607 12.0001L19.5303 5.53039L18.4697 4.46973L12 10.9394Z" fill="currentColor"/></svg></span> <span class="hide-visually collapsed-text">collapsed</span> </button> <div class="primary-menu-container"><ul id="menu-financial-switching-1" class="menu-wrapper"><li class="menu-item menu-item-type-taxonomy menu-item-object-category menu-item-239"><a href="https://arthurvandermerwe.com/category/hsm/">HSM</a></li> <li class="menu-item menu-item-type-taxonomy menu-item-object-category menu-item-240"><a href="https://arthurvandermerwe.com/category/cryptography-2/">Cryptography</a></li> <li class="menu-item menu-item-type-taxonomy menu-item-object-category current-post-ancestor current-menu-parent current-post-parent menu-item-241"><a href="https://arthurvandermerwe.com/category/financial-switching/">Financial Switching</a></li> <li class="menu-item menu-item-type-taxonomy menu-item-object-category menu-item-242"><a href="https://arthurvandermerwe.com/category/atm-tracing/">ATM Tracing</a></li> <li class="menu-item menu-item-type-post_type menu-item-object-page menu-item-27"><a href="https://arthurvandermerwe.com/downloads/">Downloads</a></li> <li class="menu-item menu-item-type-post_type menu-item-object-page menu-item-5"><a href="https://arthurvandermerwe.com/about/">About</a></li> </ul></div> </nav> <div class="menu-button-container"> <button id="primary-open-menu" class="button open"> <span class="dropdown-icon open">Menu <svg class="svg-icon" width="24" height="24" aria-hidden="true" role="img" focusable="false" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg"><path fill-rule="evenodd" clip-rule="evenodd" d="M4.5 6H19.5V7.5H4.5V6ZM4.5 12H19.5V13.5H4.5V12ZM19.5 18H4.5V19.5H19.5V18Z" fill="currentColor"/></svg></span> <span class="hide-visually expanded-text">expanded</span> </button> </div> <div class="menu-button-container"> </div> </header> <div id="content" class="site-content"> <section id="primary" class="content-area"> <main id="main" class="site-main" role="main"> <article id="post-131" class="post-131 post type-post status-publish format-standard hentry category-financial-switching tag-3574932 tag-1799144 tag-diy tag-kca tag-kek1 tag-kek2 tag-keks tag-ki tag-kia tag-kmach tag-management-information tag-pksp tag-pos-terminal tag-ppasn tag-ppid tag-rsa tag-sktcu tag-tcu tag-terminal-manufacturer entry"> <header class="entry-header default-max-width"> <h1 class="entry-title">EFTPOS Initialisation using RSA Cryptography</h1> <div class="entry-meta"> </div> </header> <div class="entry-content"> <div class="cs-rating pd-rating" id="pd_rating_holder_7692610_post_131"></div><br/><p>Before you start with RSA, you should generate a public and private key pair using your HSM. These can be group keys or specific to the terminal you need to connect. Your terminal manufacturer will also provide its public key and modulus. Using these keys you will be able to calculate the TMK1 and TMK2 and also your session keys. The process is in fact very simple.</p> <p>Here is an example of how to create these keys using a Thales HSM</p> <p>Generating an 1536 bit RSA Key</p> <p>Input</p> <pre><span style="color:#999999;"><em>001-EI2153601</em></span></pre> <p>Output</p> <pre><span style="color:#999999;">001-EJ00</span></pre> <pre><span style="color:#000000;">Public Key</span> <span style="color:#999999;">3081C80281C0A0FAFB1789B87F6F075B04FE60B5F20AC9D658E6C9B9B4E82AD41FD748A5A00CAF0A5691D2D01726AB073AFB7B91810430F240244E0D4737A397C747FC67C622B12E3654DCDF4F58EE29241616AE7EBA08A1E16DB79E09529FB6CA92213F2DFAB3F677793BF977D640107FBF9833842A0BFBF5F871709E78EE5A152E0BBBBBDDED80D193BAC3033FE412B3C420532A8B309942E76F7A9FB4475B8EDEFDDADC4C101FF02F74BEE0261C681E314124654C39411E2CE56FE719A45CA7592B8431D30203010001</span></pre> <pre><span style="color:#000000;">Private key length</span> <span style="color:#999999;">0488</span></pre> <pre><span style="color:#000000;">Private Key</span> <span style="color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span></pre> <p>Generate a <span style="color:#333333;">MAC</span> on 1536 RSA key</p> <p>Input</p> <pre><span style="color:#999999;">002-EO01<3081C80281C0A0FAFB1789B87F6F075B04FE60B5F20AC9D658E6C9B9B4E82AD41FD748A5A00CAF0A5691D2D01726AB073AFB7B91810430F240244E0D4737A397C747FC67C622B12E3654DCDF4F58EE29241616AE7EBA08A1E16DB79E09529FB6CA92213F2DFAB3F677793BF977D640107FBF9833842A0BFBF5F871709E78EE5A152E0BBBBBDDED80D193BAC3033FE412B3C420532A8B309942E76F7A9FB4475B8EDEFDDADC4C101FF02F74BEE0261C681E314124654C39411E2CE56FE719A45CA7592B8431D30203010001></span></pre> <p>Output</p> <pre><span style="color:#999999;">002-EP00<<span style="color:#333333;">C905141E</span>><3081C80281C0A0FAFB1789B87F6F075B04FE60B5F20AC9D658E6C9B9B4E82AD41FD748A5A00CAF0A5691D2D01726AB073AFB7B91810430F240244E0D4737A397C747FC67C622B12E3654DCDF4F58EE29241616AE7EBA08A1E16DB79E09529FB6CA92213F2DFAB3F677793BF977D640107FBF9833842A0BFBF5F871709E78EE5A152E0BBBBBDDED80D193BAC3033FE412B3C420532A8B309942E76F7A9FB4475B8EDEFDDADC4C101FF02F74BEE0261C681E314124654C39411E2CE56FE719A45CA7592B8431D30203010101></span></pre> <p>This is a generic version of RSA encryption using POS pinheads, there are variations in the field. Please keep that in mind when reading this.</p> <p>Now when a POS terminal logs on for the first time it shall always logon using a 9820 message with a network management information code of 191, containing the TCU public key signed by the manufacturer’s secret key, and the un-enciphered PPID.</p> <p>The Financial Switch shall respond with a 9830 message with the same network management information code, communicating the public key of the sponsor host (PKsp), and a random number.</p> <p>The PIN Pad shall then generate the KI and send a 9820 message with a network management information code of 192 to the Financial Switch, containing the KI, PPID, date & time stamp, the random number and user data enciphered under the Financial Switch’s public key (PKsp) and signed by the TCU’s secret key (SKtcu). You will need to extract this information using your HSM H8 command, example below:</p> <p>Input Data:</p> <pre><span style="color:#999999;"><em>001-H801<FDC694A6></em></span> <span style="color:#999999;"><em><30550250AB378F98E373BBC6FA5E698F4F095A6D693A851E53C35CC9633947399C09D70932776DBEA5F2F0F0C4DAB4693CACB4D07B19242FF0435C55E3D4E28EFD563457F7EBA31BE1123DEA78CEC1573716130B020103></em></span> <span style="color:#999999;"><em>;990192</em></span> <span style="color:#999999;"><em><99658789F42672E7C51CB6ECAF3F061BBABCD954D4113E1CD9BD7BD4DF1BD94E6CBC10F497E9AE68265E87F77BFF293AA2D9FDE9C1A8F12A04D9B4D8DB9F5EAEE4690883838DEF670174E70C79E674F97E2457DD85EEEB346A17DD1F39CB3E8B2D69949436051994F8687F0FEE6558F28180D5A63946CD60604B1C82F6AE14454F5824CBFDCEE07478D2F0239299B64CD900DFF7559423E98F0C7AB8229933E4DD5A5E0BD736F8172668676949493577E323FC8EC592437F6DF20EDB5FBB6E92></em></span> <span style="color:#999999;"><em>;0080</em></span> <span style="color:#999999;"><em><7C9DDD3AEFF1D50BAFD11DBAF240BE827BAA156F9E8BB555CC019E183B3708F26EBE6C94702A9AD7CC1D2159CF587437532969D113C70BD622EB81AFC06E9408F1B69F3ED838A9EADFB41FB0E6E4202E></em></span> <span style="color:#999999;"><em>;1234567890123456;000</em></span></pre> <p>Response:</p> <pre><span style="color:#999999;"><em>001-H900</em></span> <span style="color:#999999;"><em>H604A678C8C78E1B9CFD415220D418E76</em></span> <span style="color:#999999;"><em>U9912C5D8B113B5E9D6787D57EE9E43BA</em></span> <span style="color:#999999;"><em>1122334455</em></span> <span style="color:#999999;"><em>9876543210987654</em></span></pre> <p> </p> <p>The Financial Switch shall check the PPID and random number. If the check fails, it will respond with a 9830 with a response code of “63”.</p> <p>Where the Financial Switch is satisfied with the contents of the second 9820 message, it shall respond with the KCA and the KMACH enciphered under KI and its AIIC in the clear. When the PIN Pad has deciphered KCA and KMACH, it shall erase KI.</p> <p>At this time the PIN Pad shall calculate the KIA. When the KIA has been calculated, the PIN Pad shall erase KCA.</p> <p>The POS terminal shall then generate a 9820 message with a network management information code of 193 to the Financial Switch containing the PPID and the Financial Switch shall respond with a 9830 response containing the two initial KEKs and the PPASN.</p> <p>You can generate this using the C0/C1 HSM command.</p> <p>The POS terminal shall validate the MAC on the two KEKs and the PPASN and, if the MAC is valid, shall install KEK1, KEK2 and the PPASN and shall calculate the single length DES key KMACI. These keys are the terminal initial keys, that will updated in the season key exchange.</p> <p>Once this has been carried out, the PIN Pad shall erase the KIA.</p> <p>When these tasks have been completed, the POS terminal shall carry out its normal logon and session key installation with the Financial Switch. As the processing (initial logon then normal logon and session key installation) completes, the POS terminal will move into the “Ready” state.</p> <p>easy as pie!</p> <span id="wordads-inline-marker" style="display: none;"></span><div id="atatags-702045275-6746fdf9509b4"> <script type="text/javascript"> __ATA.cmd.push(function() { __ATA.initVideoSlot('atatags-702045275-6746fdf9509b4', { sectionId: '702045275', format: 'inread' }); }); </script> </div> <div id="atatags-702045271-6746fdf950a0a"></div> <script> __ATA.cmd.push(function() { __ATA.initDynamicSlot({ id: 'atatags-702045271-6746fdf950a0a', location: 120, formFactor: '001', label: { text: 'Advertisements', }, creative: { reportAd: { text: 'Report this ad', }, privacySettings: { text: 'Privacy', } } }); }); </script><div id="jp-post-flair" class="sharedaddy sd-rating-enabled sd-like-enabled sd-sharing-enabled"><div class="sharedaddy sd-sharing-enabled"><div class="robots-nocontent sd-block sd-social sd-social-icon sd-sharing"><h3 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href="https://arthurvandermerwe.com/2015/05/20/atm-pin-encryption-using-3des/" rel="prev"><span class="meta-nav" aria-hidden="true">Previous Post</span> <span class="screen-reader-text">Previous post:</span> <br/><span class="post-title">ATM Pin encryption using 3DES</span></a></div><div class="nav-next"><a href="https://arthurvandermerwe.com/2015/05/30/dukpt-explained-with-examples/" rel="next"><span class="meta-nav" aria-hidden="true">Next Post</span> <span class="screen-reader-text">Next post:</span> <br/><span class="post-title">DUKPT Explained with examples</span></a></div></div> </nav> <div id="comments" class="comments-area default-max-width"> <h2 class="comments-title"> 1 Comment </h2> <ol class="comment-list commentlist"> <li class="comment byuser comment-author-bravehoang2 even thread-even depth-1" id="comment-346"> <div id="div-comment-346" class="comment-body"> <div class="comment-author vcard"> <img alt='' src='https://1.gravatar.com/avatar/12f9b5958ee473267ded7dae88a8c0fcb3297739944d4777d385a12f7f41dffb?s=42&d=https%3A%2F%2F1.gravatar.com%2Favatar%2Fad516503a11cd5ca435acc9bb6523536%3Fs%3D42&r=G' srcset='https://1.gravatar.com/avatar/12f9b5958ee473267ded7dae88a8c0fcb3297739944d4777d385a12f7f41dffb?s=42&d=https%3A%2F%2F1.gravatar.com%2Favatar%2Fad516503a11cd5ca435acc9bb6523536%3Fs%3D42&r=G 1x, https://1.gravatar.com/avatar/12f9b5958ee473267ded7dae88a8c0fcb3297739944d4777d385a12f7f41dffb?s=63&d=https%3A%2F%2F1.gravatar.com%2Favatar%2Fad516503a11cd5ca435acc9bb6523536%3Fs%3D63&r=G 1.5x, https://1.gravatar.com/avatar/12f9b5958ee473267ded7dae88a8c0fcb3297739944d4777d385a12f7f41dffb?s=84&d=https%3A%2F%2F1.gravatar.com%2Favatar%2Fad516503a11cd5ca435acc9bb6523536%3Fs%3D84&r=G 2x, https://1.gravatar.com/avatar/12f9b5958ee473267ded7dae88a8c0fcb3297739944d4777d385a12f7f41dffb?s=126&d=https%3A%2F%2F1.gravatar.com%2Favatar%2Fad516503a11cd5ca435acc9bb6523536%3Fs%3D126&r=G 3x, https://1.gravatar.com/avatar/12f9b5958ee473267ded7dae88a8c0fcb3297739944d4777d385a12f7f41dffb?s=168&d=https%3A%2F%2F1.gravatar.com%2Favatar%2Fad516503a11cd5ca435acc9bb6523536%3Fs%3D168&r=G 4x' class='avatar avatar-42' height='42' width='42' loading='lazy' decoding='async' /> <cite class="fn"><a href="http://hoavulove.wordpress.com" class="url" rel="ugc external nofollow">Brave Hoang</a></cite> <span class="says">says:</span> </div> <div class="comment-meta commentmetadata"> <a href="https://arthurvandermerwe.com/2015/05/28/eftpos-initialisation-using-rsa-cryptography/#comment-346">January 30, 2017 at 11:59 am</a> </div> <p>Dear Van Der Merwe,<br /> Thank you so much for this article.<br /> I have some questions about it.</p> <p>“The PIN Pad shall then generate the KI and send a 9820 message with a network management information code of 192 to the Financial Switch, containing the KI, PPID, date & time stamp, the random number and user data enciphered under the Financial Switch’s public key (PKsp) and signed by the TCU’s secret key (SKtcu).”<br /> ==> I am working on Verifone terminal, but I don’t know how to use PINPad to generate the KI. Do you know it?<br /> What algorithm is used to do encipher (by PKsp) and sign (SKtcu) in this step?</p> <p>“it shall respond with the KCA and the KMACH enciphered under KI and its AIIC in the clear. When the PIN Pad has deciphered KCA and KMACH, it shall erase KI.”<br /> ==> What algorithm is used to do encipher KCA and KMACH under KI?</p> <p>“At this time the PIN Pad shall calculate the KIA. When the KIA has been calculated, the PIN Pad shall erase KCA.”<br /> ==> How to use PINpad to calculate KIA?</p> <p>Can you please help me on issues of key change session? We can pay for you.</p> <p>Thank you,<br /> Brave Hoang.</p> <div class="reply"><a rel="nofollow" class="comment-reply-link" href="https://arthurvandermerwe.com/2015/05/28/eftpos-initialisation-using-rsa-cryptography/?replytocom=346#respond" data-commentid="346" data-postid="131" data-belowelement="div-comment-346" data-respondelement="respond" data-replyto="Reply to Brave Hoang" aria-label="Reply to Brave Hoang">Reply</a></div> </div> </li> </ol> <div id="respond" class="comment-respond"> <h3 id="reply-title" class="comment-reply-title">Leave a Comment <small><a rel="nofollow" id="cancel-comment-reply-link" href="/2015/05/28/eftpos-initialisation-using-rsa-cryptography/#respond" style="display:none;">Cancel reply</a></small></h3><form action="https://arthurvandermerwe.com/wp-comments-post.php" method="post" id="commentform" class="comment-form" novalidate> <div id="comment-form__verbum" class="transparent"></div><div class="verbum-form-meta"><input type='hidden' name='comment_post_ID' value='131' id='comment_post_ID' /> <input type='hidden' name='comment_parent' id='comment_parent' value='0' /> <input type="hidden" name="highlander_comment_nonce" id="highlander_comment_nonce" value="8cabd16eb8" /> <input type="hidden" name="verbum_show_subscription_modal" value="" /></div><p style="display: none;"><input type="hidden" id="akismet_comment_nonce" name="akismet_comment_nonce" value="6a62c706e7" /></p><p style="display: none !important;" class="akismet-fields-container" data-prefix="ak_"><label>Δ<textarea name="ak_hp_textarea" cols="45" rows="8" maxlength="100"></textarea></label><input type="hidden" id="ak_js_1" name="ak_js" value="237"/><script>document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() );</script></p></form> </div> </div> </main> </section> </div> <footer id="colophon" class="site-footer default-max-width" role="contentinfo" aria-label="Footer"> <div class="widget-area"> <div class="widget-column footer-widget-1"> <section id="recent-posts-4" class="widget widget_recent_entries"> <h2 class="widget-title">Recent Posts</h2><nav aria-label="Recent Posts"> <ul> <li> <a href="https://arthurvandermerwe.com/2020/02/16/a-brief-comparison-of-as2805-and-key-blocks/">A brief comparison of AS2805 and (TR-31) Key Blocks</a> </li> <li> <a href="https://arthurvandermerwe.com/2020/01/19/what-is-the-random-oracle-model-and-why-should-you-care-part-5-a-few-thoughts-on-cryptographic-engineering/">What is the random oracle model and why should you care? 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