CINXE.COM

<!doctype html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1" /> <link rel="profile" href="https://gmpg.org/xfn/11" /> <title>June 2014 – Cryptography & Payments</title> <script type="text/javascript"> WebFontConfig = {"google":{"families":["Source+Sans+Pro:r,i,b,bi:latin,latin-ext"]},"api_url":"https:\/\/fonts-api.wp.com\/css"}; (function() { var wf = document.createElement('script'); wf.src = 'https://s0.wp.com/wp-content/plugins/custom-fonts/js/webfont.js'; wf.type = 'text/javascript'; wf.async = 'true'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(wf, s); })(); </script><style id="jetpack-custom-fonts-css"></style> <meta name='robots' content='max-image-preview:large' /> <meta name="google-site-verification" content="Zw5b22p04kGoy8Ch3FcgAxEamB26jLd3FALtlnOF6RA" />  <script id="wpcom_remote_login_js"> var wpcom_remote_login_extra_auth = ''; function wpcom_remote_login_remove_dom_node_id( element_id ) { var dom_node = document.getElementById( element_id ); if ( dom_node ) { dom_node.parentNode.removeChild( dom_node ); } } function wpcom_remote_login_remove_dom_node_classes( class_name ) { var dom_nodes = document.querySelectorAll( '.' + class_name ); for ( var i = 0; i < dom_nodes.length; i++ ) { dom_nodes[ i ].parentNode.removeChild( dom_nodes[ i ] ); } } function wpcom_remote_login_final_cleanup() { wpcom_remote_login_remove_dom_node_classes( "wpcom_remote_login_msg" ); wpcom_remote_login_remove_dom_node_id( "wpcom_remote_login_key" ); wpcom_remote_login_remove_dom_node_id( "wpcom_remote_login_validate" ); wpcom_remote_login_remove_dom_node_id( "wpcom_remote_login_js" ); wpcom_remote_login_remove_dom_node_id( "wpcom_request_access_iframe" ); wpcom_remote_login_remove_dom_node_id( "wpcom_request_access_styles" ); } // Watch for messages back from the remote login window.addEventListener( "message", function( e ) { if ( e.origin === "https://r-login.wordpress.com" ) { var data = {}; try { data = JSON.parse( e.data ); } catch( e ) { wpcom_remote_login_final_cleanup(); return; } if ( data.msg === 'LOGIN' ) { // Clean up the login check iframe wpcom_remote_login_remove_dom_node_id( "wpcom_remote_login_key" ); var id_regex = new RegExp( /^[0-9]+$/ ); var token_regex = new RegExp( /^.*|.*|.*$/ ); if ( token_regex.test( data.token ) && id_regex.test( data.wpcomid ) ) { // We have everything we need to ask for a login var script = document.createElement( "script" ); script.setAttribute( "id", "wpcom_remote_login_validate" ); script.src = '/remote-login.php?wpcom_remote_login=validate' + '&wpcomid=' + data.wpcomid + '&token=' + encodeURIComponent( data.token ) + '&host=' + window.location.protocol + '//' + window.location.hostname + '&postid=47' + '&is_singular='; document.body.appendChild( script ); } return; } // Safari ITP, not logged in, so redirect if ( data.msg === 'LOGIN-REDIRECT' ) { window.location = 'https://wordpress.com/log-in?redirect_to=' + window.location.href; return; } // Safari ITP, storage access failed, remove the request if ( data.msg === 'LOGIN-REMOVE' ) { var css_zap = 'html { -webkit-transition: margin-top 1s; transition: margin-top 1s; } /* 9001 */ html { margin-top: 0 !important; } * html body { margin-top: 0 !important; } @media screen and ( max-width: 782px ) { html { margin-top: 0 !important; } * html body { margin-top: 0 !important; } }'; var style_zap = document.createElement( 'style' ); style_zap.type = 'text/css'; style_zap.appendChild( document.createTextNode( css_zap ) ); document.body.appendChild( style_zap ); var e = document.getElementById( 'wpcom_request_access_iframe' ); e.parentNode.removeChild( e ); document.cookie = 'wordpress_com_login_access=denied; path=/; max-age=31536000'; return; } // Safari ITP if ( data.msg === 'REQUEST_ACCESS' ) { console.log( 'request access: safari' ); // Check ITP iframe enable/disable knob if ( wpcom_remote_login_extra_auth !== 'safari_itp_iframe' ) { return; } // If we are in a "private window" there is no ITP. var private_window = false; try { var opendb = window.openDatabase( null, null, null, null ); } catch( e ) { private_window = true; } if ( private_window ) { console.log( 'private window' ); return; } var iframe = document.createElement( 'iframe' ); iframe.id = 'wpcom_request_access_iframe'; iframe.setAttribute( 'scrolling', 'no' ); iframe.setAttribute( 'sandbox', 'allow-storage-access-by-user-activation allow-scripts allow-same-origin allow-top-navigation-by-user-activation' ); iframe.src = 'https://r-login.wordpress.com/remote-login.php?wpcom_remote_login=request_access&origin=' + encodeURIComponent( data.origin ) + '&wpcomid=' + encodeURIComponent( data.wpcomid ); var css = 'html { -webkit-transition: margin-top 1s; transition: margin-top 1s; } /* 9001 */ html { margin-top: 46px !important; } * html body { margin-top: 46px !important; } @media screen and ( max-width: 660px ) { html { margin-top: 71px !important; } * html body { margin-top: 71px !important; } #wpcom_request_access_iframe { display: block; height: 71px !important; } } #wpcom_request_access_iframe { border: 0px; height: 46px; position: fixed; top: 0; left: 0; width: 100%; min-width: 100%; z-index: 99999; background: #23282d; } '; var style = document.createElement( 'style' ); style.type = 'text/css'; style.id = 'wpcom_request_access_styles'; style.appendChild( document.createTextNode( css ) ); document.body.appendChild( style ); document.body.appendChild( iframe ); } if ( data.msg === 'DONE' ) { wpcom_remote_login_final_cleanup(); } } }, false ); // Inject the remote login iframe after the page has had a chance to load // more critical resources window.addEventListener( "DOMContentLoaded", function( e ) { var iframe = document.createElement( "iframe" ); iframe.style.display = "none"; iframe.setAttribute( "scrolling", "no" ); iframe.setAttribute( "id", "wpcom_remote_login_key" ); iframe.src = "https://r-login.wordpress.com/remote-login.php" + "?wpcom_remote_login=key" + "&origin=aHR0cHM6Ly9hcnRodXJ2YW5kZXJtZXJ3ZS5jb20%3D" + "&wpcomid=70204527" + "&time=1739796161"; document.body.appendChild( iframe ); }, false ); </script> <link rel='dns-prefetch' href='//s1.wp.com' /> <link rel='dns-prefetch' href='//s2.wp.com' /> <link rel='dns-prefetch' href='//s0.wp.com' /> <link rel='dns-prefetch' href='//fonts-api.wp.com' /> <link rel='dns-prefetch' href='//af.pubmine.com' /> <link rel='dns-prefetch' href='//s.pubmine.com' /> <link rel='dns-prefetch' href='//x.bidswitch.net' /> <link rel='dns-prefetch' href='//static.criteo.net' /> <link rel='dns-prefetch' href='//ib.adnxs.com' /> <link rel='dns-prefetch' href='//aax.amazon-adsystem.com' /> <link rel='dns-prefetch' href='//bidder.criteo.com' /> <link rel='dns-prefetch' href='//cas.criteo.com' /> <link rel='dns-prefetch' href='//gum.criteo.com' /> <link rel='dns-prefetch' href='//ads.pubmatic.com' /> <link rel='dns-prefetch' href='//gads.pubmatic.com' /> <link rel='dns-prefetch' href='//tpc.googlesyndication.com' /> <link rel='dns-prefetch' href='//ad.doubleclick.net' /> <link rel='dns-prefetch' href='//googleads.g.doubleclick.net' /> <link rel='dns-prefetch' href='//www.googletagservices.com' /> <link rel='dns-prefetch' href='//cdn.switchadhub.com' /> <link rel='dns-prefetch' href='//delivery.g.switchadhub.com' /> <link rel='dns-prefetch' href='//delivery.swid.switchadhub.com' /> <link rel='dns-prefetch' href='//a.teads.tv' /> <link rel='dns-prefetch' href='//prebid.media.net' /> <link rel='dns-prefetch' href='//adserver-us.adtech.advertising.com' /> <link rel='dns-prefetch' href='//fastlane.rubiconproject.com' /> <link rel='dns-prefetch' href='//prebid-server.rubiconproject.com' /> <link rel='dns-prefetch' href='//hb-api.omnitagjs.com' /> <link rel='dns-prefetch' href='//mtrx.go.sonobi.com' /> <link rel='dns-prefetch' href='//apex.go.sonobi.com' /> <link rel='dns-prefetch' href='//u.openx.net' /> <link rel="alternate" type="application/rss+xml" title="Cryptography & Payments » Feed" href="https://arthurvandermerwe.com/feed/" /> <link rel="alternate" type="application/rss+xml" title="Cryptography & Payments » Comments Feed" href="https://arthurvandermerwe.com/comments/feed/" /> <script type="text/javascript"> /* <![CDATA[ */ function addLoadEvent(func) { var oldonload = window.onload; if (typeof window.onload != 'function') { window.onload = func; } else { window.onload = function () { oldonload(); func(); } } } /* ]]> */ </script> <script> window._wpemojiSettings = {"baseUrl":"https:\/\/s0.wp.com\/wp-content\/mu-plugins\/wpcom-smileys\/twemoji\/2\/72x72\/","ext":".png","svgUrl":"https:\/\/s0.wp.com\/wp-content\/mu-plugins\/wpcom-smileys\/twemoji\/2\/svg\/","svgExt":".svg","source":{"concatemoji":"https:\/\/s2.wp.com\/wp-includes\/js\/wp-emoji-release.min.js?m=1719498190i&ver=6.7.2-RC1-59780"}}; /*! This file is auto-generated */ !function(i,n){var o,s,e;function c(e){try{var t={supportTests:e,timestamp:(new Date).valueOf()};sessionStorage.setItem(o,JSON.stringify(t))}catch(e){}}function p(e,t,n){e.clearRect(0,0,e.canvas.width,e.canvas.height),e.fillText(t,0,0);var t=new Uint32Array(e.getImageData(0,0,e.canvas.width,e.canvas.height).data),r=(e.clearRect(0,0,e.canvas.width,e.canvas.height),e.fillText(n,0,0),new Uint32Array(e.getImageData(0,0,e.canvas.width,e.canvas.height).data));return t.every(function(e,t){return e===r[t]})}function u(e,t,n){switch(t){case"flag":return n(e,"\ud83c\udff3\ufe0f\u200d\u26a7\ufe0f","\ud83c\udff3\ufe0f\u200b\u26a7\ufe0f")?!1:!n(e,"\ud83c\uddfa\ud83c\uddf3","\ud83c\uddfa\u200b\ud83c\uddf3")&&!n(e,"\ud83c\udff4\udb40\udc67\udb40\udc62\udb40\udc65\udb40\udc6e\udb40\udc67\udb40\udc7f","\ud83c\udff4\u200b\udb40\udc67\u200b\udb40\udc62\u200b\udb40\udc65\u200b\udb40\udc6e\u200b\udb40\udc67\u200b\udb40\udc7f");case"emoji":return!n(e,"\ud83d\udc26\u200d\u2b1b","\ud83d\udc26\u200b\u2b1b")}return!1}function f(e,t,n){var r="undefined"!=typeof WorkerGlobalScope&&self instanceof WorkerGlobalScope?new OffscreenCanvas(300,150):i.createElement("canvas"),a=r.getContext("2d",{willReadFrequently:!0}),o=(a.textBaseline="top",a.font="600 32px Arial",{});return e.forEach(function(e){o[e]=t(a,e,n)}),o}function t(e){var t=i.createElement("script");t.src=e,t.defer=!0,i.head.appendChild(t)}"undefined"!=typeof Promise&&(o="wpEmojiSettingsSupports",s=["flag","emoji"],n.supports={everything:!0,everythingExceptFlag:!0},e=new Promise(function(e){i.addEventListener("DOMContentLoaded",e,{once:!0})}),new Promise(function(t){var n=function(){try{var e=JSON.parse(sessionStorage.getItem(o));if("object"==typeof e&&"number"==typeof e.timestamp&&(new Date).valueOf()<e.timestamp+604800&&"object"==typeof e.supportTests)return e.supportTests}catch(e){}return null}();if(!n){if("undefined"!=typeof Worker&&"undefined"!=typeof OffscreenCanvas&&"undefined"!=typeof URL&&URL.createObjectURL&&"undefined"!=typeof Blob)try{var e="postMessage("+f.toString()+"("+[JSON.stringify(s),u.toString(),p.toString()].join(",")+"));",r=new Blob([e],{type:"text/javascript"}),a=new Worker(URL.createObjectURL(r),{name:"wpTestEmojiSupports"});return void(a.onmessage=function(e){c(n=e.data),a.terminate(),t(n)})}catch(e){}c(n=f(s,u,p))}t(n)}).then(function(e){for(var t in e)n.supports[t]=e[t],n.supports.everything=n.supports.everything&&n.supports[t],"flag"!==t&&(n.supports.everythingExceptFlag=n.supports.everythingExceptFlag&&n.supports[t]);n.supports.everythingExceptFlag=n.supports.everythingExceptFlag&&!n.supports.flag,n.DOMReady=!1,n.readyCallback=function(){n.DOMReady=!0}}).then(function(){return e}).then(function(){var e;n.supports.everything||(n.readyCallback(),(e=n.source||{}).concatemoji?t(e.concatemoji):e.wpemoji&&e.twemoji&&(t(e.twemoji),t(e.wpemoji)))}))}((window,document),window._wpemojiSettings); </script> <link crossorigin='anonymous' rel='stylesheet' id='all-css-0-1' href='https://s2.wp.com/wp-content/blog-plugins/wordads/global.css?m=1561495466i&cssminify=yes' type='text/css' media='all' /> <style id='wp-emoji-styles-inline-css'> img.wp-smiley, img.emoji { display: inline !important; border: none !important; box-shadow: none !important; height: 1em !important; width: 1em !important; margin: 0 0.07em !important; vertical-align: -0.1em !important; background: none !important; padding: 0 !important; } </style> <link crossorigin='anonymous' rel='stylesheet' id='all-css-2-1' href='https://s1.wp.com/_static/??-eJydzEEOwiAQheELCVNso90YzwKUEOoIZGao4fZWN+66cPny8v3wqsqXLCELVGwxZYbY9ukCxf2hANt50IM24FrCBRwW/1CYHFnqwNIxaM98gsPQVzGsQar9cNtLExUpLf8myErKkX/8/ryZ6zjP08WMZn0DL6xPzg==&cssminify=yes' type='text/css' media='all' /> <style id='wp-block-library-inline-css'> .has-text-align-justify { text-align:justify; } .has-text-align-justify{text-align:justify;} </style> <link crossorigin='anonymous' rel='stylesheet' id='all-css-4-1' href='https://s2.wp.com/_static/??-eJzTLy/QzcxLzilNSS3WzyrWz01NyUxMzUnNTc0rQeEU5CRWphbp5qSmJyZX6uVm5uklFxfr6OPTDpRD5sM02efaGpoZmFkYGRuZGmQBAHPvL0Y=&cssminify=yes' type='text/css' media='all' /> <style id='jetpack-sharing-buttons-style-inline-css'> .jetpack-sharing-buttons__services-list{display:flex;flex-direction:row;flex-wrap:wrap;gap:0;list-style-type:none;margin:5px;padding:0}.jetpack-sharing-buttons__services-list.has-small-icon-size{font-size:12px}.jetpack-sharing-buttons__services-list.has-normal-icon-size{font-size:16px}.jetpack-sharing-buttons__services-list.has-large-icon-size{font-size:24px}.jetpack-sharing-buttons__services-list.has-huge-icon-size{font-size:36px}@media print{.jetpack-sharing-buttons__services-list{display:none!important}}.editor-styles-wrapper .wp-block-jetpack-sharing-buttons{gap:0;padding-inline-start:0}ul.jetpack-sharing-buttons__services-list.has-background{padding:1.25em 2.375em} </style> <link crossorigin='anonymous' rel='stylesheet' id='all-css-6-1' href='https://s2.wp.com/wp-content/plugins/coblocks/2.18.1-simple-rev.4/dist/coblocks-style.css?m=1681832297i&cssminify=yes' type='text/css' media='all' /> <style id='classic-theme-styles-inline-css'> /*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} </style> <link crossorigin='anonymous' rel='stylesheet' id='all-css-8-1' href='https://s1.wp.com/_static/??/wp-content/mu-plugins/core-compat/wp-mediaelement.css,/wp-content/mu-plugins/wpcom-bbpress-premium-themes.css?m=1432920480j&cssminify=yes' type='text/css' media='all' /> <style id='global-styles-inline-css'> :root{--wp--preset--aspect-ratio--square: 1;--wp--preset--aspect-ratio--4-3: 4/3;--wp--preset--aspect-ratio--3-4: 3/4;--wp--preset--aspect-ratio--3-2: 3/2;--wp--preset--aspect-ratio--2-3: 2/3;--wp--preset--aspect-ratio--16-9: 16/9;--wp--preset--aspect-ratio--9-16: 9/16;--wp--preset--color--black: #000000;--wp--preset--color--cyan-bluish-gray: #abb8c3;--wp--preset--color--white: #ffffff;--wp--preset--color--pale-pink: #f78da7;--wp--preset--color--vivid-red: #cf2e2e;--wp--preset--color--luminous-vivid-orange: #ff6900;--wp--preset--color--luminous-vivid-amber: #fcb900;--wp--preset--color--light-green-cyan: #7bdcb5;--wp--preset--color--vivid-green-cyan: #00d084;--wp--preset--color--pale-cyan-blue: #8ed1fc;--wp--preset--color--vivid-cyan-blue: #0693e3;--wp--preset--color--vivid-purple: #9b51e0;--wp--preset--color--primary: #000000;--wp--preset--color--secondary: #3C8067;--wp--preset--color--foreground: #333333;--wp--preset--color--tertiary: #FAFBF6;--wp--preset--color--background: #FFFFFF;--wp--preset--gradient--vivid-cyan-blue-to-vivid-purple: linear-gradient(135deg,rgba(6,147,227,1) 0%,rgb(155,81,224) 100%);--wp--preset--gradient--light-green-cyan-to-vivid-green-cyan: linear-gradient(135deg,rgb(122,220,180) 0%,rgb(0,208,130) 100%);--wp--preset--gradient--luminous-vivid-amber-to-luminous-vivid-orange: linear-gradient(135deg,rgba(252,185,0,1) 0%,rgba(255,105,0,1) 100%);--wp--preset--gradient--luminous-vivid-orange-to-vivid-red: linear-gradient(135deg,rgba(255,105,0,1) 0%,rgb(207,46,46) 100%);--wp--preset--gradient--very-light-gray-to-cyan-bluish-gray: linear-gradient(135deg,rgb(238,238,238) 0%,rgb(169,184,195) 100%);--wp--preset--gradient--cool-to-warm-spectrum: linear-gradient(135deg,rgb(74,234,220) 0%,rgb(151,120,209) 20%,rgb(207,42,186) 40%,rgb(238,44,130) 60%,rgb(251,105,98) 80%,rgb(254,248,76) 100%);--wp--preset--gradient--blush-light-purple: linear-gradient(135deg,rgb(255,206,236) 0%,rgb(152,150,240) 100%);--wp--preset--gradient--blush-bordeaux: linear-gradient(135deg,rgb(254,205,165) 0%,rgb(254,45,45) 50%,rgb(107,0,62) 100%);--wp--preset--gradient--luminous-dusk: linear-gradient(135deg,rgb(255,203,112) 0%,rgb(199,81,192) 50%,rgb(65,88,208) 100%);--wp--preset--gradient--pale-ocean: linear-gradient(135deg,rgb(255,245,203) 0%,rgb(182,227,212) 50%,rgb(51,167,181) 100%);--wp--preset--gradient--electric-grass: linear-gradient(135deg,rgb(202,248,128) 0%,rgb(113,206,126) 100%);--wp--preset--gradient--midnight: linear-gradient(135deg,rgb(2,3,129) 0%,rgb(40,116,252) 100%);--wp--preset--gradient--hard-diagonal: linear-gradient(to bottom right, #3C8067 49.9%, #FAFBF6 50%);--wp--preset--gradient--hard-diagonal-inverted: linear-gradient(to top left, #3C8067 49.9%, #FAFBF6 50%);--wp--preset--gradient--hard-horizontal: linear-gradient(to bottom, #3C8067 50%, #FAFBF6 50%);--wp--preset--gradient--hard-horizontal-inverted: linear-gradient(to top, #3C8067 50%, #FAFBF6 50%);--wp--preset--gradient--diagonal: linear-gradient(to bottom right, #3C8067, #FAFBF6);--wp--preset--gradient--diagonal-inverted: linear-gradient(to top left, #3C8067, #FAFBF6);--wp--preset--gradient--horizontal: linear-gradient(to bottom, #3C8067, #FAFBF6);--wp--preset--gradient--horizontal-inverted: linear-gradient(to top, #3C8067, #FAFBF6);--wp--preset--gradient--stripe: linear-gradient(to bottom, transparent 20%, #3C8067 20%, #3C8067 80%, transparent 80%);--wp--preset--font-size--small: 16px;--wp--preset--font-size--medium: 20px;--wp--preset--font-size--large: 24px;--wp--preset--font-size--x-large: 42px;--wp--preset--font-size--tiny: 14px;--wp--preset--font-size--normal: 18px;--wp--preset--font-size--huge: 28px;--wp--preset--font-family--albert-sans: 'Albert Sans', sans-serif;--wp--preset--font-family--alegreya: Alegreya, serif;--wp--preset--font-family--arvo: Arvo, serif;--wp--preset--font-family--bodoni-moda: 'Bodoni Moda', serif;--wp--preset--font-family--bricolage-grotesque: 'Bricolage Grotesque', sans-serif;--wp--preset--font-family--cabin: Cabin, sans-serif;--wp--preset--font-family--chivo: Chivo, sans-serif;--wp--preset--font-family--commissioner: Commissioner, sans-serif;--wp--preset--font-family--cormorant: Cormorant, serif;--wp--preset--font-family--courier-prime: 'Courier Prime', monospace;--wp--preset--font-family--crimson-pro: 'Crimson Pro', serif;--wp--preset--font-family--dm-mono: 'DM Mono', monospace;--wp--preset--font-family--dm-sans: 'DM Sans', sans-serif;--wp--preset--font-family--dm-serif-display: 'DM Serif Display', serif;--wp--preset--font-family--domine: Domine, serif;--wp--preset--font-family--eb-garamond: 'EB Garamond', serif;--wp--preset--font-family--epilogue: Epilogue, sans-serif;--wp--preset--font-family--fahkwang: Fahkwang, sans-serif;--wp--preset--font-family--figtree: Figtree, sans-serif;--wp--preset--font-family--fira-sans: 'Fira Sans', sans-serif;--wp--preset--font-family--fjalla-one: 'Fjalla One', sans-serif;--wp--preset--font-family--fraunces: Fraunces, serif;--wp--preset--font-family--gabarito: Gabarito, system-ui;--wp--preset--font-family--ibm-plex-mono: 'IBM Plex Mono', monospace;--wp--preset--font-family--ibm-plex-sans: 'IBM Plex Sans', sans-serif;--wp--preset--font-family--ibarra-real-nova: 'Ibarra Real Nova', serif;--wp--preset--font-family--instrument-serif: 'Instrument Serif', serif;--wp--preset--font-family--inter: Inter, sans-serif;--wp--preset--font-family--josefin-sans: 'Josefin Sans', sans-serif;--wp--preset--font-family--jost: Jost, sans-serif;--wp--preset--font-family--libre-baskerville: 'Libre Baskerville', serif;--wp--preset--font-family--libre-franklin: 'Libre Franklin', sans-serif;--wp--preset--font-family--literata: Literata, serif;--wp--preset--font-family--lora: Lora, serif;--wp--preset--font-family--merriweather: Merriweather, serif;--wp--preset--font-family--montserrat: Montserrat, sans-serif;--wp--preset--font-family--newsreader: Newsreader, serif;--wp--preset--font-family--noto-sans-mono: 'Noto Sans Mono', sans-serif;--wp--preset--font-family--nunito: Nunito, sans-serif;--wp--preset--font-family--open-sans: 'Open Sans', sans-serif;--wp--preset--font-family--overpass: Overpass, sans-serif;--wp--preset--font-family--pt-serif: 'PT Serif', serif;--wp--preset--font-family--petrona: Petrona, serif;--wp--preset--font-family--piazzolla: Piazzolla, serif;--wp--preset--font-family--playfair-display: 'Playfair Display', serif;--wp--preset--font-family--plus-jakarta-sans: 'Plus Jakarta Sans', sans-serif;--wp--preset--font-family--poppins: Poppins, sans-serif;--wp--preset--font-family--raleway: Raleway, sans-serif;--wp--preset--font-family--roboto: Roboto, sans-serif;--wp--preset--font-family--roboto-slab: 'Roboto Slab', serif;--wp--preset--font-family--rubik: Rubik, sans-serif;--wp--preset--font-family--rufina: Rufina, serif;--wp--preset--font-family--sora: Sora, sans-serif;--wp--preset--font-family--source-sans-3: 'Source Sans 3', sans-serif;--wp--preset--font-family--source-serif-4: 'Source Serif 4', serif;--wp--preset--font-family--space-mono: 'Space Mono', monospace;--wp--preset--font-family--syne: Syne, sans-serif;--wp--preset--font-family--texturina: Texturina, serif;--wp--preset--font-family--urbanist: Urbanist, sans-serif;--wp--preset--font-family--work-sans: 'Work Sans', sans-serif;--wp--preset--spacing--20: 0.44rem;--wp--preset--spacing--30: 0.67rem;--wp--preset--spacing--40: 1rem;--wp--preset--spacing--50: 1.5rem;--wp--preset--spacing--60: 2.25rem;--wp--preset--spacing--70: 3.38rem;--wp--preset--spacing--80: 5.06rem;--wp--preset--shadow--natural: 6px 6px 9px rgba(0, 0, 0, 0.2);--wp--preset--shadow--deep: 12px 12px 50px rgba(0, 0, 0, 0.4);--wp--preset--shadow--sharp: 6px 6px 0px rgba(0, 0, 0, 0.2);--wp--preset--shadow--outlined: 6px 6px 0px -3px rgba(255, 255, 255, 1), 6px 6px rgba(0, 0, 0, 1);--wp--preset--shadow--crisp: 6px 6px 0px rgba(0, 0, 0, 1);}:where(.is-layout-flex){gap: 0.5em;}:where(.is-layout-grid){gap: 0.5em;}body .is-layout-flex{display: flex;}.is-layout-flex{flex-wrap: wrap;align-items: center;}.is-layout-flex > :is(*, div){margin: 0;}body .is-layout-grid{display: grid;}.is-layout-grid > :is(*, div){margin: 0;}:where(.wp-block-columns.is-layout-flex){gap: 2em;}:where(.wp-block-columns.is-layout-grid){gap: 2em;}:where(.wp-block-post-template.is-layout-flex){gap: 1.25em;}:where(.wp-block-post-template.is-layout-grid){gap: 1.25em;}.has-black-color{color: var(--wp--preset--color--black) !important;}.has-cyan-bluish-gray-color{color: var(--wp--preset--color--cyan-bluish-gray) !important;}.has-white-color{color: var(--wp--preset--color--white) !important;}.has-pale-pink-color{color: var(--wp--preset--color--pale-pink) !important;}.has-vivid-red-color{color: var(--wp--preset--color--vivid-red) !important;}.has-luminous-vivid-orange-color{color: var(--wp--preset--color--luminous-vivid-orange) !important;}.has-luminous-vivid-amber-color{color: var(--wp--preset--color--luminous-vivid-amber) !important;}.has-light-green-cyan-color{color: var(--wp--preset--color--light-green-cyan) !important;}.has-vivid-green-cyan-color{color: var(--wp--preset--color--vivid-green-cyan) !important;}.has-pale-cyan-blue-color{color: var(--wp--preset--color--pale-cyan-blue) !important;}.has-vivid-cyan-blue-color{color: var(--wp--preset--color--vivid-cyan-blue) !important;}.has-vivid-purple-color{color: var(--wp--preset--color--vivid-purple) !important;}.has-black-background-color{background-color: var(--wp--preset--color--black) !important;}.has-cyan-bluish-gray-background-color{background-color: var(--wp--preset--color--cyan-bluish-gray) !important;}.has-white-background-color{background-color: var(--wp--preset--color--white) !important;}.has-pale-pink-background-color{background-color: var(--wp--preset--color--pale-pink) !important;}.has-vivid-red-background-color{background-color: var(--wp--preset--color--vivid-red) !important;}.has-luminous-vivid-orange-background-color{background-color: var(--wp--preset--color--luminous-vivid-orange) !important;}.has-luminous-vivid-amber-background-color{background-color: var(--wp--preset--color--luminous-vivid-amber) !important;}.has-light-green-cyan-background-color{background-color: var(--wp--preset--color--light-green-cyan) !important;}.has-vivid-green-cyan-background-color{background-color: var(--wp--preset--color--vivid-green-cyan) !important;}.has-pale-cyan-blue-background-color{background-color: var(--wp--preset--color--pale-cyan-blue) !important;}.has-vivid-cyan-blue-background-color{background-color: var(--wp--preset--color--vivid-cyan-blue) !important;}.has-vivid-purple-background-color{background-color: var(--wp--preset--color--vivid-purple) !important;}.has-black-border-color{border-color: var(--wp--preset--color--black) !important;}.has-cyan-bluish-gray-border-color{border-color: var(--wp--preset--color--cyan-bluish-gray) !important;}.has-white-border-color{border-color: var(--wp--preset--color--white) !important;}.has-pale-pink-border-color{border-color: var(--wp--preset--color--pale-pink) !important;}.has-vivid-red-border-color{border-color: var(--wp--preset--color--vivid-red) !important;}.has-luminous-vivid-orange-border-color{border-color: var(--wp--preset--color--luminous-vivid-orange) !important;}.has-luminous-vivid-amber-border-color{border-color: var(--wp--preset--color--luminous-vivid-amber) !important;}.has-light-green-cyan-border-color{border-color: var(--wp--preset--color--light-green-cyan) !important;}.has-vivid-green-cyan-border-color{border-color: var(--wp--preset--color--vivid-green-cyan) !important;}.has-pale-cyan-blue-border-color{border-color: var(--wp--preset--color--pale-cyan-blue) !important;}.has-vivid-cyan-blue-border-color{border-color: var(--wp--preset--color--vivid-cyan-blue) !important;}.has-vivid-purple-border-color{border-color: var(--wp--preset--color--vivid-purple) !important;}.has-vivid-cyan-blue-to-vivid-purple-gradient-background{background: var(--wp--preset--gradient--vivid-cyan-blue-to-vivid-purple) !important;}.has-light-green-cyan-to-vivid-green-cyan-gradient-background{background: var(--wp--preset--gradient--light-green-cyan-to-vivid-green-cyan) !important;}.has-luminous-vivid-amber-to-luminous-vivid-orange-gradient-background{background: var(--wp--preset--gradient--luminous-vivid-amber-to-luminous-vivid-orange) !important;}.has-luminous-vivid-orange-to-vivid-red-gradient-background{background: var(--wp--preset--gradient--luminous-vivid-orange-to-vivid-red) !important;}.has-very-light-gray-to-cyan-bluish-gray-gradient-background{background: var(--wp--preset--gradient--very-light-gray-to-cyan-bluish-gray) !important;}.has-cool-to-warm-spectrum-gradient-background{background: var(--wp--preset--gradient--cool-to-warm-spectrum) !important;}.has-blush-light-purple-gradient-background{background: var(--wp--preset--gradient--blush-light-purple) !important;}.has-blush-bordeaux-gradient-background{background: var(--wp--preset--gradient--blush-bordeaux) !important;}.has-luminous-dusk-gradient-background{background: var(--wp--preset--gradient--luminous-dusk) !important;}.has-pale-ocean-gradient-background{background: var(--wp--preset--gradient--pale-ocean) !important;}.has-electric-grass-gradient-background{background: var(--wp--preset--gradient--electric-grass) !important;}.has-midnight-gradient-background{background: var(--wp--preset--gradient--midnight) !important;}.has-small-font-size{font-size: var(--wp--preset--font-size--small) !important;}.has-medium-font-size{font-size: var(--wp--preset--font-size--medium) !important;}.has-large-font-size{font-size: var(--wp--preset--font-size--large) !important;}.has-x-large-font-size{font-size: var(--wp--preset--font-size--x-large) !important;}.has-albert-sans-font-family{font-family: var(--wp--preset--font-family--albert-sans) !important;}.has-alegreya-font-family{font-family: var(--wp--preset--font-family--alegreya) !important;}.has-arvo-font-family{font-family: var(--wp--preset--font-family--arvo) !important;}.has-bodoni-moda-font-family{font-family: var(--wp--preset--font-family--bodoni-moda) !important;}.has-bricolage-grotesque-font-family{font-family: var(--wp--preset--font-family--bricolage-grotesque) !important;}.has-cabin-font-family{font-family: var(--wp--preset--font-family--cabin) !important;}.has-chivo-font-family{font-family: var(--wp--preset--font-family--chivo) !important;}.has-commissioner-font-family{font-family: var(--wp--preset--font-family--commissioner) !important;}.has-cormorant-font-family{font-family: var(--wp--preset--font-family--cormorant) !important;}.has-courier-prime-font-family{font-family: var(--wp--preset--font-family--courier-prime) !important;}.has-crimson-pro-font-family{font-family: var(--wp--preset--font-family--crimson-pro) !important;}.has-dm-mono-font-family{font-family: var(--wp--preset--font-family--dm-mono) !important;}.has-dm-sans-font-family{font-family: var(--wp--preset--font-family--dm-sans) !important;}.has-dm-serif-display-font-family{font-family: var(--wp--preset--font-family--dm-serif-display) !important;}.has-domine-font-family{font-family: var(--wp--preset--font-family--domine) !important;}.has-eb-garamond-font-family{font-family: var(--wp--preset--font-family--eb-garamond) !important;}.has-epilogue-font-family{font-family: var(--wp--preset--font-family--epilogue) !important;}.has-fahkwang-font-family{font-family: var(--wp--preset--font-family--fahkwang) !important;}.has-figtree-font-family{font-family: var(--wp--preset--font-family--figtree) !important;}.has-fira-sans-font-family{font-family: var(--wp--preset--font-family--fira-sans) !important;}.has-fjalla-one-font-family{font-family: var(--wp--preset--font-family--fjalla-one) !important;}.has-fraunces-font-family{font-family: var(--wp--preset--font-family--fraunces) !important;}.has-gabarito-font-family{font-family: var(--wp--preset--font-family--gabarito) !important;}.has-ibm-plex-mono-font-family{font-family: var(--wp--preset--font-family--ibm-plex-mono) !important;}.has-ibm-plex-sans-font-family{font-family: var(--wp--preset--font-family--ibm-plex-sans) !important;}.has-ibarra-real-nova-font-family{font-family: var(--wp--preset--font-family--ibarra-real-nova) !important;}.has-instrument-serif-font-family{font-family: var(--wp--preset--font-family--instrument-serif) !important;}.has-inter-font-family{font-family: var(--wp--preset--font-family--inter) !important;}.has-josefin-sans-font-family{font-family: var(--wp--preset--font-family--josefin-sans) !important;}.has-jost-font-family{font-family: var(--wp--preset--font-family--jost) !important;}.has-libre-baskerville-font-family{font-family: var(--wp--preset--font-family--libre-baskerville) !important;}.has-libre-franklin-font-family{font-family: var(--wp--preset--font-family--libre-franklin) !important;}.has-literata-font-family{font-family: var(--wp--preset--font-family--literata) !important;}.has-lora-font-family{font-family: var(--wp--preset--font-family--lora) !important;}.has-merriweather-font-family{font-family: var(--wp--preset--font-family--merriweather) !important;}.has-montserrat-font-family{font-family: var(--wp--preset--font-family--montserrat) !important;}.has-newsreader-font-family{font-family: var(--wp--preset--font-family--newsreader) !important;}.has-noto-sans-mono-font-family{font-family: var(--wp--preset--font-family--noto-sans-mono) !important;}.has-nunito-font-family{font-family: var(--wp--preset--font-family--nunito) !important;}.has-open-sans-font-family{font-family: var(--wp--preset--font-family--open-sans) !important;}.has-overpass-font-family{font-family: var(--wp--preset--font-family--overpass) !important;}.has-pt-serif-font-family{font-family: var(--wp--preset--font-family--pt-serif) !important;}.has-petrona-font-family{font-family: var(--wp--preset--font-family--petrona) !important;}.has-piazzolla-font-family{font-family: var(--wp--preset--font-family--piazzolla) !important;}.has-playfair-display-font-family{font-family: var(--wp--preset--font-family--playfair-display) !important;}.has-plus-jakarta-sans-font-family{font-family: var(--wp--preset--font-family--plus-jakarta-sans) !important;}.has-poppins-font-family{font-family: var(--wp--preset--font-family--poppins) !important;}.has-raleway-font-family{font-family: var(--wp--preset--font-family--raleway) !important;}.has-roboto-font-family{font-family: var(--wp--preset--font-family--roboto) !important;}.has-roboto-slab-font-family{font-family: var(--wp--preset--font-family--roboto-slab) !important;}.has-rubik-font-family{font-family: var(--wp--preset--font-family--rubik) !important;}.has-rufina-font-family{font-family: var(--wp--preset--font-family--rufina) !important;}.has-sora-font-family{font-family: var(--wp--preset--font-family--sora) !important;}.has-source-sans-3-font-family{font-family: var(--wp--preset--font-family--source-sans-3) !important;}.has-source-serif-4-font-family{font-family: var(--wp--preset--font-family--source-serif-4) !important;}.has-space-mono-font-family{font-family: var(--wp--preset--font-family--space-mono) !important;}.has-syne-font-family{font-family: var(--wp--preset--font-family--syne) !important;}.has-texturina-font-family{font-family: var(--wp--preset--font-family--texturina) !important;}.has-urbanist-font-family{font-family: var(--wp--preset--font-family--urbanist) !important;}.has-work-sans-font-family{font-family: var(--wp--preset--font-family--work-sans) !important;} :where(.wp-block-columns.is-layout-flex){gap: 2em;}:where(.wp-block-columns.is-layout-grid){gap: 2em;} :root :where(.wp-block-pullquote){font-size: 1.5em;line-height: 1.6;} :where(.wp-block-post-template.is-layout-flex){gap: 1.25em;}:where(.wp-block-post-template.is-layout-grid){gap: 1.25em;} </style> <link rel='stylesheet' id='seedlet-fonts-css' href='https://fonts-api.wp.com/css?family=Fira+Sans%3Aital%2Cwght%400%2C400%3B0%2C500%3B1%2C400%7CPlayfair+Display%3Aital%2Cwght%400%2C400%3B0%2C700%3B1%2C400&subset=latin%2Clatin-ext' media='all' /> <link crossorigin='anonymous' rel='stylesheet' id='all-css-12-1' href='https://s0.wp.com/_static/??/wp-content/themes/pub/seedlet/style.css,/wp-content/themes/pub/seedlet/assets/css/style-navigation.css?m=1738187798j&cssminify=yes' type='text/css' media='all' /> <link crossorigin='anonymous' rel='stylesheet' id='print-css-13-1' href='https://s1.wp.com/wp-content/themes/pub/seedlet/assets/css/print.css?m=1738187798i&cssminify=yes' type='text/css' media='print' /> <link crossorigin='anonymous' rel='stylesheet' id='all-css-14-1' href='https://s1.wp.com/wp-content/themes/pub/seedlet/inc/wpcom-style.css?m=1594046753i&cssminify=yes' type='text/css' media='all' /> <style id='akismet-widget-style-inline-css'> .a-stats { --akismet-color-mid-green: #357b49; --akismet-color-white: #fff; --akismet-color-light-grey: #f6f7f7; max-width: 350px; width: auto; } .a-stats * { all: unset; box-sizing: border-box; } .a-stats strong { font-weight: 600; } .a-stats a.a-stats__link, .a-stats a.a-stats__link:visited, .a-stats a.a-stats__link:active { background: var(--akismet-color-mid-green); border: none; box-shadow: none; border-radius: 8px; color: var(--akismet-color-white); cursor: pointer; display: block; font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen-Sans', 'Ubuntu', 'Cantarell', 'Helvetica Neue', sans-serif; font-weight: 500; padding: 12px; text-align: center; text-decoration: none; transition: all 0.2s ease; } /* Extra specificity to deal with TwentyTwentyOne focus style */ .widget .a-stats a.a-stats__link:focus { background: var(--akismet-color-mid-green); color: var(--akismet-color-white); text-decoration: none; } .a-stats a.a-stats__link:hover { filter: brightness(110%); box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06), 0 0 2px rgba(0, 0, 0, 0.16); } .a-stats .count { color: var(--akismet-color-white); display: block; font-size: 1.5em; line-height: 1.4; padding: 0 13px; white-space: nowrap; } </style> <link crossorigin='anonymous' rel='stylesheet' id='all-css-16-1' href='https://s1.wp.com/_static/??-eJzTLy/QTc7PK0nNK9HPLdUtyClNz8wr1i9KTcrJTwcy0/WTi5G5ekCujj52Temp+bo5+cmJJZn5eSgc3bScxMwikFb7XFtDE1NLExMLc0OTLACohS2q&cssminify=yes' type='text/css' media='all' /> <style id='jetpack-global-styles-frontend-style-inline-css'> :root { --font-headings: unset; --font-base: unset; --font-headings-default: -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Oxygen-Sans,Ubuntu,Cantarell,"Helvetica Neue",sans-serif; --font-base-default: -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Oxygen-Sans,Ubuntu,Cantarell,"Helvetica Neue",sans-serif;} </style> <link crossorigin='anonymous' rel='stylesheet' id='all-css-18-1' href='https://s2.wp.com/wp-content/themes/h4/global.css?m=1420737423i&cssminify=yes' type='text/css' media='all' /> <script id="wpcom-actionbar-placeholder-js-extra"> var actionbardata = {"siteID":"70204527","postID":"0","siteURL":"https:\/\/arthurvandermerwe.com","xhrURL":"https:\/\/arthurvandermerwe.com\/wp-admin\/admin-ajax.php","nonce":"03e1243f92","isLoggedIn":"","statusMessage":"","subsEmailDefault":"instantly","proxyScriptUrl":"https:\/\/s0.wp.com\/wp-content\/js\/wpcom-proxy-request.js?ver=20211021","i18n":{"followedText":"New posts from this site will now appear in your <a href=\"https:\/\/wordpress.com\/reader\">Reader<\/a>","foldBar":"Collapse this bar","unfoldBar":"Expand this bar","shortLinkCopied":"Shortlink copied to clipboard."}}; </script> <script id="jetpack-mu-wpcom-settings-js-before"> var JETPACK_MU_WPCOM_SETTINGS = {"assetsUrl":"https:\/\/s1.wp.com\/wp-content\/mu-plugins\/jetpack-mu-wpcom-plugin\/sun\/jetpack_vendor\/automattic\/jetpack-mu-wpcom\/src\/build\/"}; </script> <script crossorigin='anonymous' type='text/javascript' src='https://s1.wp.com/_static/??-eJyVzckOwjAMBNAfwriL2A6Ib0kbtyRyEytOt7+HiAvixmkOozeDq0AfQ6aQ0SsmziApbvvR6wG/uvykiRRl7lCJLFNGo0pZi+pVYTFJQWLYB8fc/MUd1TUMbvtFHccRhOfRBcU1JmusQs8Ffm4nwaUpASEGGK2k98RjuteXpjq11fl68y+6C1Fw'></script> <script id="rlt-proxy-js-after"> rltInitialize( {"token":null,"iframeOrigins":["https:\/\/widgets.wp.com"]} ); </script> <link rel="EditURI" type="application/rsd+xml" title="RSD" href="https://arthurvandermerwe.wordpress.com/xmlrpc.php?rsd" /> <meta name="generator" content="WordPress.com" />  <meta property="og:type" content="website" /> <meta property="og:title" content="June 2014 – Cryptography & Payments" /> <meta property="og:site_name" content="Cryptography & Payments" /> <meta property="og:image" content="https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=200" /> <meta property="og:image:width" content="200" /> <meta property="og:image:height" content="200" /> <meta property="og:image:alt" content="" /> <meta property="og:locale" content="en_US" />  <link rel='openid.server' href='https://arthurvandermerwe.com/?openidserver=1' /> <link rel='openid.delegate' href='https://arthurvandermerwe.com/' /> <link rel="search" type="application/opensearchdescription+xml" href="https://arthurvandermerwe.com/osd.xml" title="Cryptography & Payments" /> <link rel="search" type="application/opensearchdescription+xml" href="https://s1.wp.com/opensearch.xml" title="WordPress.com" /> <style type="text/css"> .recentcomments a { display: inline !important; padding: 0 !important; margin: 0 !important; } table.recentcommentsavatartop img.avatar, table.recentcommentsavatarend img.avatar { border: 0px; margin: 0; } table.recentcommentsavatartop a, table.recentcommentsavatarend a { border: 0px !important; background-color: transparent !important; } td.recentcommentsavatarend, td.recentcommentsavatartop { padding: 0px 0px 1px 0px; margin: 0px; } td.recentcommentstextend { border: none !important; padding: 0px 0px 2px 10px; } .rtl td.recentcommentstextend { padding: 0px 10px 2px 0px; } td.recentcommentstexttop { border: none; padding: 0px 0px 0px 10px; } .rtl td.recentcommentstexttop { padding: 0px 10px 0px 0px; } </style> <meta name="description" content="5 posts published by arthurvdmerwe during June 2014" /> <script> var wa_smart = { 'network_id': 3905, 'site_id': 560111, 'page_id': 1700829, 'blog_id': 70204527, 'post_id': null, 'theme': 'pub/seedlet', 'target': 'wp_blog_id=70204527;language=en', '_': { 'title': 'Advertisement', 'privacy_settings': 'Privacy Settings' }, 'top': { 'enabled': false, 'format_id': 135099 }, 'inline': { 'enabled': false, 'format_id': 110354, 'max_slots': 20, 'max_blaze_slots': 20 }, 'belowpost': { 'enabled': false, 'format_id': 134071 }, 'bottom_sticky': { 'enabled': false, 'format_id': 117571 }, 'sidebar': { 'enabled': false, 'format_id': 134686 }, 'sidebar_sticky_right': { 'enabled': false, 'format_id': 135281 }, 'gutenberg_rectangle': { 'enabled': false, 'format_id': 134788 }, 'gutenberg_leaderboard': { 'enabled': false, 'format_id': 135073 }, 'gutenberg_mobile_leaderboard': { 'enabled': false, 'format_id': 135098 }, 'gutenberg_skyscraper': { 'enabled': false, 'format_id': 135088 }, 'sidebar_widget_mediumrectangle': { 'enabled': false, 'format_id': 137624 }, 'sidebar_widget_leaderboard': { 'enabled': false, 'format_id': 137625 }, 'sidebar_widget_wideskyscraper': { 'enabled': false, 'format_id': 137626 }, 'shortcode': { 'enabled': false, 'format_id': 137678 } }; wa_smart.cmd = []; </script> <script type="text/javascript"> function __ATA_CC() {var v = document.cookie.match('(^|;) ?personalized-ads-consent=([^;]*)(;|$)');return v ? 1 : 0;} var __ATA_PP = { 'pt': 3, 'ht': 1, 'tn': 'seedlet', 'uloggedin': 0, 'amp': false, 'consent': __ATA_CC(), 'gdpr_applies': false, 'ad': { 'label': { 'text': 'Advertisements' }, 'reportAd': { 'text': 'Report this ad' } }, 'disabled_slot_formats': [], 'siteid': 70204527, 'afp_ad_client': 'pub-6694573643007653' }; var __ATA = __ATA || {}; __ATA.cmd = __ATA.cmd || []; __ATA.criteo = __ATA.criteo || {}; __ATA.criteo.cmd = __ATA.criteo.cmd || []; </script> <script type="text/javascript"> (function(){var g=Date.now||function(){return+new Date};function h(a,b){a:{for(var c=a.length,d="string"==typeof a?a.split(""):a,e=0;e<c;e++)if(e in d&&b.call(void 0,d[e],e,a)){b=e;break a}b=-1}return 0>b?null:"string"==typeof a?a.charAt(b):a[b]};function k(a,b,c){c=null!=c?"="+encodeURIComponent(String(c)):"";if(b+=c){c=a.indexOf("#");0>c&&(c=a.length);var d=a.indexOf("?");if(0>d||d>c){d=c;var e=""}else e=a.substring(d+1,c);a=[a.substr(0,d),e,a.substr(c)];c=a[1];a[1]=b?c?c+"&"+b:b:c;a=a[0]+(a[1]?"?"+a[1]:"")+a[2]}return a};var l=0;function m(a,b){var c=document.createElement("script");c.src=a;c.onload=function(){b&&b(void 0)};c.onerror=function(){b&&b("error")};a=document.getElementsByTagName("head");var d;a&&0!==a.length?d=a[0]:d=document.documentElement;d.appendChild(c)}function n(a){var b=void 0===b?document.cookie:b;return(b=h(b.split("; "),function(c){return-1!=c.indexOf(a+"=")}))?b.split("=")[1]:""}function p(a){return"string"==typeof a&&0<a.length} function r(a,b,c){b=void 0===b?"":b;c=void 0===c?".":c;var d=[];Object.keys(a).forEach(function(e){var f=a[e],q=typeof f;"object"==q&&null!=f||"function"==q?d.push(r(f,b+e+c)):null!==f&&void 0!==f&&(e=encodeURIComponent(b+e),d.push(e+"="+encodeURIComponent(f)))});return d.filter(p).join("&")}function t(a,b){a||((window.__ATA||{}).config=b.c,m(b.url))}var u=Math.floor(1E13*Math.random()),v=window.__ATA||{};window.__ATA=v;window.__ATA.cmd=v.cmd||[];v.rid=u;v.createdAt=g();var w=window.__ATA||{},x="s.pubmine.com"; w&&w.serverDomain&&(x=w.serverDomain);var y="//"+x+"/conf",z=window.top===window,A=window.__ATA_PP&&window.__ATA_PP.gdpr_applies,B="boolean"===typeof A?Number(A):null,C=window.__ATA_PP||null,D=z?document.referrer?document.referrer:null:null,E=z?window.location.href:document.referrer?document.referrer:null,F,G=n("__ATA_tuuid");F=G?G:null;var H=window.innerWidth+"x"+window.innerHeight,I=n("usprivacy"),J=r({gdpr:B,pp:C,rid:u,src:D,ref:E,tuuid:F,vp:H,us_privacy:I?I:null},"","."); (function(a){var b=void 0===b?"cb":b;l++;var c="callback__"+g().toString(36)+"_"+l.toString(36);a=k(a,b,c);window[c]=function(d){t(void 0,d)};m(a,function(d){d&&t(d)})})(y+"?"+J);}).call(this); </script> <script> var sas_fallback = sas_fallback || []; sas_fallback.push( { tag: "<div id="atatags-702045271-{{unique_id}}"></div><script>__ATA.cmd.push(function() {__ATA.initDynamicSlot({id: \'atatags-702045271-{{unique_id}}\',location: 120,formFactor: \'001\',label: {text: \'Advertisements\',},creative: {reportAd: {text: \'Report this ad\',},privacySettings: {text: \'Privacy\',}}});});</script>", type: 'belowpost' }, { tag: "<div id="atatags-702045271-{{unique_id}}"></div><script>__ATA.cmd.push(function() {__ATA.initDynamicSlot({id: \'atatags-702045271-{{unique_id}}\',location: 310,formFactor: \'001\',label: {text: \'Advertisements\',},creative: {reportAd: {text: \'Report this ad\',},privacySettings: {text: \'Privacy\',}}});});</script>", type: 'inline' }, { tag: "<div id="atatags-702045271-{{unique_id}}"></div><script>__ATA.cmd.push(function() {__ATA.initDynamicSlot({id: \'atatags-702045271-{{unique_id}}\',location: 140,formFactor: \'003\',label: {text: \'Advertisements\',},creative: {reportAd: {text: \'Report this ad\',},privacySettings: {text: \'Privacy\',}}});});</script>", type: 'sidebar' }, { tag: "<div id="atatags-702045271-{{unique_id}}"></div><script>__ATA.cmd.push(function() {__ATA.initDynamicSlot({id: \'atatags-702045271-{{unique_id}}\',location: 110,formFactor: \'002\',label: {text: \'Advertisements\',},creative: {reportAd: {text: \'Report this ad\',},privacySettings: {text: \'Privacy\',}}});});</script>", type: 'top' } ); </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="archive date wp-embed-responsive customizer-styles-applied hfeed 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 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"> <header class="page-header default-max-width"> <h1 class="page-title"><span class="archive-prefix">Monthly Archives: </span><span class="page-description">June 2014</span></h1> </header> <article id="post-47" class="post-47 post type-post status-publish format-standard hentry category-financial-switching tag-dynamic-key-exchange tag-key-exchange entry"> <header class="entry-header default-max-width"> <h2 class="entry-title"><a href="https://arthurvandermerwe.com/2014/06/25/dynamic-key-exchange-models/" rel="bookmark">Dynamic Key Exchange Models</a></h2> </header> <div class="entry-content"> <h3 class="entry-header">Dynamic Key Exchange Models</h3> <div class="entry-content"> <div class="entry-body"> <p>I’ve had a number of people ask me recently about how to implement Dynamic Key Exchange models. Specifically, I’m talking here about ISO8583-based financial payment gateways. This post pertains to situations where you’re acting either as the Card Issuer (in which case you’re receiving payment transaction requests from the gateway) or the transaction acquirer (in which case you’re sending payment transaction requests to the gateway in order that they route it for appropriate authorization decisioning).</p> <p>There’s some terminology to square away first:</p> <p><strong>Local Master Key (‘LMK’)</strong> – This is the key you store in the HSM in order to encrypt and do software-based storage of the current Working Keys (and Base Derivation Keys if you’re using DUKPT). Also called the Master File Key (‘MFK’)</p> <p><strong>Zone PIN Key (</strong>‘<strong>ZPK’)</strong> – The ZPK is what’s used to encrypt the PIN blocks that traverse the wires between institutions. Also referred to as the ‘Working Key.’ <em><strong>This is the key that the Dynamic Key Exchange is acting upon</strong></em>. You’re obligated to change the Working Key at agreed-upon intervals (I typically advocate every 12 hours).</p> <p><strong>Zone Master Key (‘ZMK’)</strong> – Think of the ZMK as the key transportation vehicle. It’s the key that the two parties use to encrypt and exchange new ZPKs. This key is established via a key ceremony. You keep a copy of the ZMK encrypted under the LMK in a file somewhere (you’ll see how it’s used here further down this post). Also called the Key Exchange Key (‘KEK’).</p> <ol> <li>From the moment you start planning discussions with the gateway, establish RIGHT AWAY that you want field-by-field level specifics of how the Dynamic Key Exchange is to be performed. It’ll be within the context of some Network Message Exchange (e.g., 0800/0810), but that’s not granular enough – you need to know the thing down to the field-content level.</li> <li>Scour the documentation you’ve been provided to see if those details are in there. I’ve done two different gateway projects recently, and in both cases the Key Exchange details were notably absent from the doc. But, that doc exists somewhere within the gateway institution. Track it down. Get your hands on it.</li> <li>Knowledge of the Key Exchange model is – by design – not widespread throughout the gateway provider’s project personnel. Insist on getting their expert in on at least one of the planning calls. Make note of this person’s name and contact details. Establish that information channel. This is a critically important point to your success.</li> </ol> <p>At a high level, there are two models:</p> <ul> <li>You request a new ZPK from the gateway, and they provide it in the response. [I call this the ‘<strong>Pull</strong>‘ model (for obvious reasons – you pull the key from them).]</li> <li>The gateway sends you a new ZPK and you respond with a message indicating success or failure. [This, by contrast is the ‘<strong>Push</strong>‘ model.]</li> </ul> <p>Your implementation will be one of those.</p> <p>Now, I’ll provide two examples, one push, one pull.</p> <p>The sequence of events is:</p> <ol> <li>The gateway sends us a new ZPK (under ZMK) in an 0800 (MTI) Network Request.</li> <li>We obtain the ZMK (under LMK) from our files.</li> <li>We use the cryptograms from Steps 1 and 2 to create the appropriate command to the Key-Up (here, a ’12’)</li> <li>We get the response from the Key-Up (the ’13’) and validate that the Check Digits match those provided by the Issuer.</li> <li>Assuming the check in Step 4 is okay, we store the result (the ZPK under LMK) as the new Working Key.</li> <li>We send an 0810 (MTI) Network Response back to the Issuer (Note that Field 39 on our response is ’00’ – indicating success).</li> </ol> <p>There’s so much detail here worthy of comment. I’ll touch on a few things (these are the types of detail you want to bring to the surface in your reviews):</p> <ul> <li>This gateway uses ‘162’ in Field 70 to tip to us that it’s a Key Exchange in play.</li> <li>Note how we have to pluck the incoming cryptogram out of the esoteric morass of Field 123.</li> <li>We have to construct an equally cryptic Field 123 on our response.</li> </ul> <p> </p> <p>Here is the pull model:</p> <ol> <li>We request a new key from the Gateway in an 0800.</li> <li>The new key (ZPK under ZMK) comes back in an 0810.</li> <li>We fire off an ‘FA’ to the Thales 8000.</li> <li>We get the ‘FB’ back and validate the check digits.</li> <li>If okay, we store the result (the ZPK under LMK) as the new Working Key.</li> </ol> <p>Now, since we’re the initiator here we have to have a way to determine when to trigger the exchange request. We do that through a channel Logon Manager.</p> <p>You get the idea, I hope! Nail down all those details in order to maximize your chances of success. Otherwise, feel free to beat your head against a wall, because that’s what will happen if you don’t get this information.</p> </div> </div> <div id="atatags-702045271-67b32ec18df95"></div> <script> __ATA.cmd.push(function() { __ATA.initDynamicSlot({ id: 'atatags-702045271-67b32ec18df95', location: 120, formFactor: '001', label: { text: 'Advertisements', }, creative: { reportAd: { text: 'Report this ad', }, privacySettings: { text: 'Privacy', } } }); }); </script> </div> <footer class="entry-footer default-max-width"> <span class="byline"><svg class="svg-icon" width="16" height="16" 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="M15 7.5C15 9.15685 13.6569 10.5 12 10.5C10.3431 10.5 9 9.15685 9 7.5C9 5.84315 10.3431 4.5 12 4.5C13.6569 4.5 15 5.84315 15 7.5ZM16.5 7.5C16.5 9.98528 14.4853 12 12 12C9.51472 12 7.5 9.98528 7.5 7.5C7.5 5.01472 9.51472 3 12 3C14.4853 3 16.5 5.01472 16.5 7.5ZM19.5 19.5V16.245C19.5 14.729 18.271 13.5 16.755 13.5L7.245 13.5C5.72898 13.5 4.5 14.729 4.5 16.245L4.5 19.5H6L6 16.245C6 15.5574 6.5574 15 7.245 15L16.755 15C17.4426 15 18 15.5574 18 16.245V19.5H19.5Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted by</span><span class="author vcard"><a class="url fn n" href="https://arthurvandermerwe.com/author/arthurvdmerwe/">arthurvdmerwe</a></span></span><span class="posted-on"><svg class="svg-icon" width="16" height="16" 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="M19.5 7.5H4.5V19.0005C4.5 19.2764 4.72363 19.5 4.9995 19.5H19.0005C19.2764 19.5 19.5 19.2764 19.5 19.0005V7.5ZM3 7.5V4.9995V4.995C3 3.89319 3.89319 3 4.995 3H4.9995H19.0005H19.005C20.1068 3 21 3.89319 21 4.995V4.9995V7.5V19.0005C21 20.1048 20.1048 21 19.0005 21H4.9995C3.89521 21 3 20.1048 3 19.0005V7.5ZM7.5 10.5H9V12H7.5V10.5ZM9 15H7.5V16.5H9V15ZM11.25 10.5H12.75V12H11.25V10.5ZM12.75 15H11.25V16.5H12.75V15ZM15 10.5H16.5V12H15V10.5ZM16.5 15H15V16.5H16.5V15Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/25/dynamic-key-exchange-models/" rel="bookmark"><time class="entry-date published" datetime="2014-06-25T12:00:25+10:00">June 25, 2014</time><time class="updated" datetime="2014-06-25T12:01:49+10:00">June 25, 2014</time></a></span><span class="cat-links"><svg class="svg-icon" width="16" height="16" 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="M12.1979 8.25L11.2098 6.27363C11.1259 6.10593 10.9545 6 10.767 6H4.995C4.72162 6 4.5 6.22162 4.5 6.495V17.505C4.5 17.7784 4.72162 18 4.995 18H19.0005C19.2764 18 19.5 17.7764 19.5 17.5005V8.7495C19.5 8.47363 19.2764 8.25 19.0005 8.25H12.1979ZM13.125 6.75H19.0005C20.1048 6.75 21 7.64521 21 8.7495V17.5005C21 18.6048 20.1048 19.5 19.0005 19.5H4.995C3.89319 19.5 3 18.6068 3 17.505V6.495C3 5.39319 3.89319 4.5 4.995 4.5H10.767C11.5227 4.5 12.2135 4.92693 12.5514 5.60281L13.125 6.75Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted in</span><a href="https://arthurvandermerwe.com/category/financial-switching/" rel="category tag">Financial Switching</a></span><span class="tags-links"><svg class="svg-icon" width="16" height="16" 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="M3 12.2045C3 12.5941 3.15158 12.9684 3.42267 13.2482L9.71878 19.747C11.0769 21.1489 13.3201 21.1667 14.7003 19.7865L19.7873 14.6995C21.1677 13.319 21.1497 11.0753 19.7471 9.71731L13.2459 3.42238C12.9661 3.15147 12.5919 3 12.2025 3H4.5C3.67157 3 3 3.67157 3 4.5V12.2045ZM12.2025 4.5H4.5V12.2045L10.7961 18.7033C11.5714 19.5035 12.8518 19.5137 13.6396 18.7258L18.7266 13.6388C19.5146 12.8509 19.5043 11.5701 18.7037 10.7949L12.2025 4.5ZM8.4975 9.495C9.0484 9.495 9.495 9.0484 9.495 8.4975C9.495 7.9466 9.0484 7.5 8.4975 7.5C7.9466 7.5 7.5 7.9466 7.5 8.4975C7.5 9.0484 7.9466 9.495 8.4975 9.495Z" fill="currentColor"/></svg><span class="screen-reader-text">Tags:</span><a href="https://arthurvandermerwe.com/tag/dynamic-key-exchange/" rel="tag">Dynamic Key Exchange</a>, <a href="https://arthurvandermerwe.com/tag/key-exchange/" rel="tag">Key Exchange</a></span><span class="comments-link"><svg class="svg-icon" width="16" height="16" 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="M10.0458 15.0001L5.99998 17.697L5.99999 6.49478C5.99999 6.22141 6.2216 5.99979 6.49498 5.99978L17.505 5.99951C17.7784 5.9995 18 6.22113 18 6.49451L18 14.5046C18 14.778 17.7784 14.9996 17.505 14.9996L10.0458 15.0001ZM10.5 16.5L17.5051 16.4996C18.6069 16.4995 19.5 15.6063 19.5 14.5046L19.5 6.49451C19.5 5.39268 18.6068 4.49948 17.5049 4.49951L6.49494 4.49978C5.39315 4.49981 4.49999 5.39299 4.49999 6.49478L4.49998 18.3483C4.49998 18.9842 5.01549 19.4997 5.6514 19.4997C5.8787 19.4997 6.10091 19.4324 6.29004 19.3063L10.5 16.5Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/25/dynamic-key-exchange-models/#comments">1 Comment<span class="screen-reader-text"> on Dynamic Key Exchange Models</span></a></span> </footer> </article> <article id="post-45" class="post-45 post type-post status-publish format-standard hentry category-financial-switching tag-atmpin tag-ksn entry"> <header class="entry-header default-max-width"> <h2 class="entry-title"><a href="https://arthurvandermerwe.com/2014/06/25/doing-pin-translation/" rel="bookmark">Doing PIN Translation with DUKPT</a></h2> </header> <div class="entry-content"> <p class="entry-header">On PIN-enabled Debit/EBT transactions sent in from an acquirer’s point-of-sale location, your payment switch application must perform a PIN translation, typically transforming an incoming DUKPT PIN block from the POS device-initiated request into a outgoing Triple DES-encrypted PIN block that makes use of an established Zone PIN Key (“ZPK”) which would have been previously established via a dynamic key exchange with your Debit/EBT gateway provider.</p> <div class="entry-content"> <div class="entry-body">[<em>The remainder of this example assumes you’re using a Thales (formerly Racal) Hardware Security Module (“HSM”)….</em>] Using strict Thales parlance, this variant of a PIN translation request is a request to “translate a PIN from *BDK encryption to interchange key encryption.” This topic is covered in Section 27.2 (page 2-185) of the Thales reference document entitled “Host Security Module RG7000 Programmer’s Manual” (Thales reference number 1270A514 Issue 5). The CI/CJ exchange should be handled as follows: <strong>— CI —</strong> <strong>Message header</strong> – You can use as you see fit. Value is echoed back in CJ. Note that the length is constant and must be configured in HSM by administrator. <strong>Command code</strong> – CI <strong>BDK</strong> – The Base Derivation Key “in play” for this transaction. In my installations we’ve set this up as follows…</p> <ul> <li>Selected the “1A + 32H” option, where the ‘1A’ value should be set to ‘U’</li> <li>Configured such that the first six positions of the KSN represent the “key name” of the BDK injected into the PIN Pad at the transaction origination point (an acquirer can use a number of BDKs in their terminal population).</li> </ul> <p><strong>ZPK</strong> – Your current ZPK Cryptogram (obtained dynamically via a key exchange with your Debit/EBT gateway partner) and stored under your Local Master Key (“LMK”). In my installations, we’ve used the “1A + 32H” option, where the ‘1A’ value should be set to ‘U’. <strong>KSN Descriptor</strong> – This value is a bit esoteric and refers directly to the make-up of the KSN which follows. So to understand the descriptor, it’s first necessary to talk a bit about the KSN (the next field in the CI command layout). Here’s a typical KSN implementation where the acquirer has chosen a 16-position scheme:</p> <ul> <li>Positions 1 – 6: The name of the BDK injected into this device</li> <li>Positions 7 – 11: The device ID</li> <li>Positions 12 – 16: The transaction counter</li> </ul> <p>[Note that the KSN implementation has to be in synch between the PIN pad and your host-side implementations in order for this to work.] The ‘rules’ for a KSN construction are as follows (reading from left to right in the KSN): a. The ‘base derivation key identifier,’ which is mandatory and five to nine (Hex) positions in length. b. A ‘sub-key identifier,’ which Thales says is ‘optional’ but in practice is ‘reserved for future use’ (and therefore always set to zero). c. A ‘device identifier’ (mandatory), which is two to five Hex digits in length. d. A ‘transaction counter’ (mandatory) which essentially is the part “left over”. So, in the example here, the client with a 6, 0, 5, 5 implementation. With this information in hand, the KSN Descriptor (a three-position value) is better described as XYZ, where: X = base derivation key identifier length Y = sub-key identifier key length (will be zero) Z = device identifier length So, in this context, the ‘605’ submitted in my example is better visualized. ‘605’ says that the 16-digit KSN consists of a 6-position BDK ID, a 0-position sub-key, a 5-position device ID, **AND** (what’s remaining basically) a 5-position transaction counter. [NOTE: Remember that this post applies *specifically* to the Thales/RACAL implementation of PIN translation] <em>Now, with this informatation in hand, we can introduce the next field, the KSN itself…</em> <strong>KSN</strong> – Using the layout from the descriptor, a typical KSN at this acquirer might be 123456000A8001D4 where: ‘123456’ is the BDK indentifier; ‘000A8’ is the Device ID; and ‘001D4’ is the transaction counter. The BDK name embedded in a particular KSN string must find a match within your BDK cryptogram list (which you need to keep loaded into your payment switch’s encryption database). If a match is not found in the encryption database, then set your Internal Result Code to “Invalid BDK” and end the transaction. If found, the value you retrieve goes into the BDK field (as described above). <strong>Source encrypted block</strong> – The PIN block plucked from the POS device request (this is a 16H value; no ‘1A’ indicator is required). <strong>Destination PIN block</strong> – In my installations, we typically use ANSI format, so we set this to ‘01’ to signify ANSI format code <strong>Account Number</strong> – Right-most 12 positions of the PAN excluding the check digit <em>Typically, that is the END of the required CI request message (remainder of the fields in the Thales spec are not mandatory).</em> <strong>— CJ —</strong> <strong> Message header</strong> – Echoed back from CI usage. <strong>Response code</strong> – CJ <strong>Error Code</strong> – Only ‘00’ should be accepted as an exchange that “worked.” <strong>PIN length</strong> – Although this field is not used to build the 0200 message formatted for your Debit/EBT gateway, a value like ‘04’ or ‘05’ here are a pretty good indication that the translation occurred successfully. <strong>Encrypted PIN</strong> – The PIN block that will be used to build the 0200 message formatted for your Debit/EBT gateway (this is a 16H value; no ‘1A’ indicator is required). <strong>Destination PIN block</strong> – Echoed back from the device as ’01’ format code <em>Typically, that is the END of the response message (remainder of list in the vendor spec would only be present if they were provided in the CI command request)</em></div> </div> <div id="atatags-702045275-67b32ec18fb6d"> <script type="text/javascript"> __ATA.cmd.push(function() { __ATA.initVideoSlot('atatags-702045275-67b32ec18fb6d', { sectionId: '702045275', format: 'inread' }); }); </script> </div> </div> <footer class="entry-footer default-max-width"> <span class="byline"><svg class="svg-icon" width="16" height="16" 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="M15 7.5C15 9.15685 13.6569 10.5 12 10.5C10.3431 10.5 9 9.15685 9 7.5C9 5.84315 10.3431 4.5 12 4.5C13.6569 4.5 15 5.84315 15 7.5ZM16.5 7.5C16.5 9.98528 14.4853 12 12 12C9.51472 12 7.5 9.98528 7.5 7.5C7.5 5.01472 9.51472 3 12 3C14.4853 3 16.5 5.01472 16.5 7.5ZM19.5 19.5V16.245C19.5 14.729 18.271 13.5 16.755 13.5L7.245 13.5C5.72898 13.5 4.5 14.729 4.5 16.245L4.5 19.5H6L6 16.245C6 15.5574 6.5574 15 7.245 15L16.755 15C17.4426 15 18 15.5574 18 16.245V19.5H19.5Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted by</span><span class="author vcard"><a class="url fn n" href="https://arthurvandermerwe.com/author/arthurvdmerwe/">arthurvdmerwe</a></span></span><span class="posted-on"><svg class="svg-icon" width="16" height="16" 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="M19.5 7.5H4.5V19.0005C4.5 19.2764 4.72363 19.5 4.9995 19.5H19.0005C19.2764 19.5 19.5 19.2764 19.5 19.0005V7.5ZM3 7.5V4.9995V4.995C3 3.89319 3.89319 3 4.995 3H4.9995H19.0005H19.005C20.1068 3 21 3.89319 21 4.995V4.9995V7.5V19.0005C21 20.1048 20.1048 21 19.0005 21H4.9995C3.89521 21 3 20.1048 3 19.0005V7.5ZM7.5 10.5H9V12H7.5V10.5ZM9 15H7.5V16.5H9V15ZM11.25 10.5H12.75V12H11.25V10.5ZM12.75 15H11.25V16.5H12.75V15ZM15 10.5H16.5V12H15V10.5ZM16.5 15H15V16.5H16.5V15Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/25/doing-pin-translation/" rel="bookmark"><time class="entry-date published" datetime="2014-06-25T11:54:39+10:00">June 25, 2014</time><time class="updated" datetime="2015-06-11T18:21:12+10:00">June 11, 2015</time></a></span><span class="cat-links"><svg class="svg-icon" width="16" height="16" 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="M12.1979 8.25L11.2098 6.27363C11.1259 6.10593 10.9545 6 10.767 6H4.995C4.72162 6 4.5 6.22162 4.5 6.495V17.505C4.5 17.7784 4.72162 18 4.995 18H19.0005C19.2764 18 19.5 17.7764 19.5 17.5005V8.7495C19.5 8.47363 19.2764 8.25 19.0005 8.25H12.1979ZM13.125 6.75H19.0005C20.1048 6.75 21 7.64521 21 8.7495V17.5005C21 18.6048 20.1048 19.5 19.0005 19.5H4.995C3.89319 19.5 3 18.6068 3 17.505V6.495C3 5.39319 3.89319 4.5 4.995 4.5H10.767C11.5227 4.5 12.2135 4.92693 12.5514 5.60281L13.125 6.75Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted in</span><a href="https://arthurvandermerwe.com/category/financial-switching/" rel="category tag">Financial Switching</a></span><span class="tags-links"><svg class="svg-icon" width="16" height="16" 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="M3 12.2045C3 12.5941 3.15158 12.9684 3.42267 13.2482L9.71878 19.747C11.0769 21.1489 13.3201 21.1667 14.7003 19.7865L19.7873 14.6995C21.1677 13.319 21.1497 11.0753 19.7471 9.71731L13.2459 3.42238C12.9661 3.15147 12.5919 3 12.2025 3H4.5C3.67157 3 3 3.67157 3 4.5V12.2045ZM12.2025 4.5H4.5V12.2045L10.7961 18.7033C11.5714 19.5035 12.8518 19.5137 13.6396 18.7258L18.7266 13.6388C19.5146 12.8509 19.5043 11.5701 18.7037 10.7949L12.2025 4.5ZM8.4975 9.495C9.0484 9.495 9.495 9.0484 9.495 8.4975C9.495 7.9466 9.0484 7.5 8.4975 7.5C7.9466 7.5 7.5 7.9466 7.5 8.4975C7.5 9.0484 7.9466 9.495 8.4975 9.495Z" fill="currentColor"/></svg><span class="screen-reader-text">Tags:</span><a href="https://arthurvandermerwe.com/tag/atmpin/" rel="tag">ATMPin</a>, <a href="https://arthurvandermerwe.com/tag/ksn/" rel="tag">KSN</a></span><span class="comments-link"><svg class="svg-icon" width="16" height="16" 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="M10.0458 15.0001L5.99998 17.697L5.99999 6.49478C5.99999 6.22141 6.2216 5.99979 6.49498 5.99978L17.505 5.99951C17.7784 5.9995 18 6.22113 18 6.49451L18 14.5046C18 14.778 17.7784 14.9996 17.505 14.9996L10.0458 15.0001ZM10.5 16.5L17.5051 16.4996C18.6069 16.4995 19.5 15.6063 19.5 14.5046L19.5 6.49451C19.5 5.39268 18.6068 4.49948 17.5049 4.49951L6.49494 4.49978C5.39315 4.49981 4.49999 5.39299 4.49999 6.49478L4.49998 18.3483C4.49998 18.9842 5.01549 19.4997 5.6514 19.4997C5.8787 19.4997 6.10091 19.4324 6.29004 19.3063L10.5 16.5Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/25/doing-pin-translation/#respond">Leave a comment<span class="screen-reader-text"> on Doing PIN Translation with DUKPT</span></a></span> </footer> </article> <article id="post-43" class="post-43 post type-post status-publish format-standard hentry category-financial-switching tag-bank-account tag-credit-card tag-credit-cards tag-debit-transaction entry"> <header class="entry-header default-max-width"> <h2 class="entry-title"><a href="https://arthurvandermerwe.com/2014/06/25/credit-vs-debit/" rel="bookmark">Credit vs Debit</a></h2> </header> <div class="entry-content"> <p>Back in the 1980s, we had a simple, bifurcated world: there were credit cards (PIN-less and tied to a credit line); and there were ATM cards (always requiring a PIN and tied to a bank account). Muddying the waters was the advent of the so-called ‘check card,’ which can be thought of as a ‘dual mode’ card – it can be used without a PIN as sort of a ‘secured’ credit card (‘secured’ in the sense that the cardholder is dipping into real money in a bank account) or with a PIN as a debit card.</p> <p>Now, we get into some rather misleading definitions that this muddying has caused…</p> <ul> <li>When you use that check card with a PIN, it’s called <strong>Online Debit</strong>. For those of you familiar with ISO8583, that PIN-ed request is going to result in you (as the acquirer) formatting an 0200 (the typical MTI used for a Purchase/Sale) request to the Debit/EBT gateway.</li> <li>The card issuer (or its authorizer) authorizes that request and treats it as the ‘letter of record’ (my term) to debit the account in its nightly posting cycle.</li> <li>The Debit/EBT gateway may or may not require the inclusion of that Debit transaction in a nightly extract/settlement file (prepped and sent by the acquirer).</li> <li>When you use the same card without a PIN, it’s called <strong>Signature Debit</strong>, i.e., because you sign for the transaction like a credit card – of course, new regulations muddy the waters further: at some merchant categories, a signature is no longer required for purchases of < AUD$ 25, as frequenters of Starbuck’s know.</li> <li>Now, the ultimate in misleading definitions: Signature Debit is often called <strong>Offline Debit</strong>, this despite the fact that 99 times out of 100 (you’re not obligated to authorize these, but you open yourself up to chargebacks), the acquirer sends an online transaction request to get an approval decision (for ISO8583-savvy folks, you send an 0100 – the auth MTI – in these situations). Where the ‘offline’ designation comes from is that this online auth is <strong><em>not the letter of record</em></strong>. In these situations, you (as the acquirer) are obligated – assuming the transaction isn’t subsequently reversed – to put these ‘offline debit’ transactions into the settlement/extract file. And it is these items that the Issuer uses to debit the related bank account. In other words, the ‘offline’ appellation here refers to <em><strong>the manner in which the bank account ultimately gets debited</strong></em>, not whether you sent an online request at the time of purchase.</li> <li>Okay, to further complicate matters: this Offline Debit transaction is often referred to as a <strong>Credit</strong> . Ugh. Why? Well, you auth it via a 0100, like credit. And, when you stick the related entry into the nightly extract file, you format it as a Credit record. For example, in the FDR North extract file, these transactions get formatted as the Credit ‘D’ record, not the Debit/EBT ‘Q’ record. Indeed, from the perspective of a host-based payment system, you can’t tell the difference between a purchase conducted with a ‘true’ credit card and one conducted with check card in PIN-less mode. In the words of Dan Rather, “If it looks like a duck, walks like a duck, and quacks like a duck, it must be a duck.”</li> </ul> </div> <footer class="entry-footer default-max-width"> <span class="byline"><svg class="svg-icon" width="16" height="16" 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="M15 7.5C15 9.15685 13.6569 10.5 12 10.5C10.3431 10.5 9 9.15685 9 7.5C9 5.84315 10.3431 4.5 12 4.5C13.6569 4.5 15 5.84315 15 7.5ZM16.5 7.5C16.5 9.98528 14.4853 12 12 12C9.51472 12 7.5 9.98528 7.5 7.5C7.5 5.01472 9.51472 3 12 3C14.4853 3 16.5 5.01472 16.5 7.5ZM19.5 19.5V16.245C19.5 14.729 18.271 13.5 16.755 13.5L7.245 13.5C5.72898 13.5 4.5 14.729 4.5 16.245L4.5 19.5H6L6 16.245C6 15.5574 6.5574 15 7.245 15L16.755 15C17.4426 15 18 15.5574 18 16.245V19.5H19.5Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted by</span><span class="author vcard"><a class="url fn n" href="https://arthurvandermerwe.com/author/arthurvdmerwe/">arthurvdmerwe</a></span></span><span class="posted-on"><svg class="svg-icon" width="16" height="16" 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="M19.5 7.5H4.5V19.0005C4.5 19.2764 4.72363 19.5 4.9995 19.5H19.0005C19.2764 19.5 19.5 19.2764 19.5 19.0005V7.5ZM3 7.5V4.9995V4.995C3 3.89319 3.89319 3 4.995 3H4.9995H19.0005H19.005C20.1068 3 21 3.89319 21 4.995V4.9995V7.5V19.0005C21 20.1048 20.1048 21 19.0005 21H4.9995C3.89521 21 3 20.1048 3 19.0005V7.5ZM7.5 10.5H9V12H7.5V10.5ZM9 15H7.5V16.5H9V15ZM11.25 10.5H12.75V12H11.25V10.5ZM12.75 15H11.25V16.5H12.75V15ZM15 10.5H16.5V12H15V10.5ZM16.5 15H15V16.5H16.5V15Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/25/credit-vs-debit/" rel="bookmark"><time class="entry-date published" datetime="2014-06-25T11:35:40+10:00">June 25, 2014</time><time class="updated" datetime="2014-06-25T11:37:09+10:00">June 25, 2014</time></a></span><span class="cat-links"><svg class="svg-icon" width="16" height="16" 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="M12.1979 8.25L11.2098 6.27363C11.1259 6.10593 10.9545 6 10.767 6H4.995C4.72162 6 4.5 6.22162 4.5 6.495V17.505C4.5 17.7784 4.72162 18 4.995 18H19.0005C19.2764 18 19.5 17.7764 19.5 17.5005V8.7495C19.5 8.47363 19.2764 8.25 19.0005 8.25H12.1979ZM13.125 6.75H19.0005C20.1048 6.75 21 7.64521 21 8.7495V17.5005C21 18.6048 20.1048 19.5 19.0005 19.5H4.995C3.89319 19.5 3 18.6068 3 17.505V6.495C3 5.39319 3.89319 4.5 4.995 4.5H10.767C11.5227 4.5 12.2135 4.92693 12.5514 5.60281L13.125 6.75Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted in</span><a href="https://arthurvandermerwe.com/category/financial-switching/" rel="category tag">Financial Switching</a></span><span class="tags-links"><svg class="svg-icon" width="16" height="16" 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="M3 12.2045C3 12.5941 3.15158 12.9684 3.42267 13.2482L9.71878 19.747C11.0769 21.1489 13.3201 21.1667 14.7003 19.7865L19.7873 14.6995C21.1677 13.319 21.1497 11.0753 19.7471 9.71731L13.2459 3.42238C12.9661 3.15147 12.5919 3 12.2025 3H4.5C3.67157 3 3 3.67157 3 4.5V12.2045ZM12.2025 4.5H4.5V12.2045L10.7961 18.7033C11.5714 19.5035 12.8518 19.5137 13.6396 18.7258L18.7266 13.6388C19.5146 12.8509 19.5043 11.5701 18.7037 10.7949L12.2025 4.5ZM8.4975 9.495C9.0484 9.495 9.495 9.0484 9.495 8.4975C9.495 7.9466 9.0484 7.5 8.4975 7.5C7.9466 7.5 7.5 7.9466 7.5 8.4975C7.5 9.0484 7.9466 9.495 8.4975 9.495Z" fill="currentColor"/></svg><span class="screen-reader-text">Tags:</span><a href="https://arthurvandermerwe.com/tag/bank-account/" rel="tag">bank account</a>, <a href="https://arthurvandermerwe.com/tag/credit-card/" rel="tag">credit card</a>, <a href="https://arthurvandermerwe.com/tag/credit-cards/" rel="tag">credit cards</a>, <a href="https://arthurvandermerwe.com/tag/debit-transaction/" rel="tag">Debit transaction</a></span><span class="comments-link"><svg class="svg-icon" width="16" height="16" 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="M10.0458 15.0001L5.99998 17.697L5.99999 6.49478C5.99999 6.22141 6.2216 5.99979 6.49498 5.99978L17.505 5.99951C17.7784 5.9995 18 6.22113 18 6.49451L18 14.5046C18 14.778 17.7784 14.9996 17.505 14.9996L10.0458 15.0001ZM10.5 16.5L17.5051 16.4996C18.6069 16.4995 19.5 15.6063 19.5 14.5046L19.5 6.49451C19.5 5.39268 18.6068 4.49948 17.5049 4.49951L6.49494 4.49978C5.39315 4.49981 4.49999 5.39299 4.49999 6.49478L4.49998 18.3483C4.49998 18.9842 5.01549 19.4997 5.6514 19.4997C5.8787 19.4997 6.10091 19.4324 6.29004 19.3063L10.5 16.5Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/25/credit-vs-debit/#respond">Leave a comment<span class="screen-reader-text"> on Credit vs Debit</span></a></span> </footer> </article> <article id="post-41" class="post-41 post type-post status-publish format-standard hentry category-financial-switching tag-as2805 tag-australia tag-australia-standards tag-australian-payments-clearing-association tag-message-authentication entry"> <header class="entry-header default-max-width"> <h2 class="entry-title"><a href="https://arthurvandermerwe.com/2014/06/22/as2805-standards-for-eft/" rel="bookmark">AS2805 Standards for EFT</a></h2> </header> <div class="entry-content"> <p>Australia Standards 2805 (AS2805) is the standard for Electronic Funds Transfer (EFT) and Payments in Australia and New Zealand. AS2805 is also used for some implementations in South Africa and SE Asian.</p> <p>AS2805 is owned by Australia Standards and was developed by various voluntary working groups within Committee IT/5. The implementation of AS2805 standards across all industries is clearly defined by the Australian Payments Clearing Association (APCA) as part of the Consumer Electronic Clearing System (CECS) and detailed in the CECS Manual.</p> <p>Contrary to popular belief AS2805 is not a rename of the ISO8583 standard in the Australia Standards numbering system, as is the case with most international standards.</p> <p>ISO8583 was first published in 1987, while AS2805 was published two years earlier in 1985, after a lengthy period of draft and review in Australia, New Zealand and South Africa. ISO8583 consists of three (3) parts:</p> <ul> <li>Part 1: Messages, Data Elements and Code Values</li> <li>Part 2: Application and Registration Procedures for Institution Identification Codes (IIC)</li> <li>Part 3: Maintenance Procedures for Messages, Data Elements and Code Values</li> </ul> <p>All three (3) parts of ISO8583 are concentrated on only message formats between devices (EFTPOS and ATM) and an acquiring host. ISO8583 can be seen as a small subset of the AS2805 standard and there is no clear guide for uniform implementation as is the case with CECS. AS2805 on the other hand consist of at least thirty three (33) separate published parts and covers general EFT topics such as:</p> <ul> <li>Card Management & Authorisation</li> <li>Card Detail Updating</li> <li>PIN Management</li> <li>Key Management and Security</li> <li>Message Authentication</li> <li>Privacy and Data Encryption</li> <li>Communications</li> <li>Message Structure between Devices and Acquiring Host</li> <li>Message Structure between Hosts</li> <li>File Transfers</li> </ul> <p>The thirty three (33) AS2805 standards published so far are the following:</p> <table border="0" width="900"> <tbody> <tr> <td width="61"></td> <td>2805.1</td> <td>Part 1:</td> <td>Communications</td> </tr> <tr> <td></td> <td>2805.2</td> <td>Part 2:</td> <td>Message Structure, format and content</td> </tr> <tr> <td></td> <td>2805.3.1</td> <td>Part 3.1:</td> <td>PIN Management and Security – General</td> </tr> <tr> <td></td> <td>2805.3.2</td> <td>Part 3.2:</td> <td>PIN Management and Security – Offline</td> </tr> <tr> <td></td> <td>2805.4.1</td> <td>Part 4.1:</td> <td>Message Authentication – Mechanisms Using a Block Cipher</td> </tr> <tr> <td></td> <td>2805.4.2</td> <td>Part 4.2:</td> <td>Message Authentication – Mechanisms Using a Hash Function</td> </tr> <tr> <td></td> <td>2805.5.1</td> <td>Part 5.1:</td> <td>Ciphers – Data Encipherment Algorithm 1 (DEA 1)</td> </tr> <tr> <td></td> <td>2805.5.2</td> <td>Part 5.2:</td> <td>Ciphers – Modes of Operation for an n-bit block cipher algorithm</td> </tr> <tr> <td></td> <td>2805.5.3</td> <td>Part 5.3:</td> <td>Ciphers – Data Encipherment Algorithm 2 (DEA 2)</td> </tr> <tr> <td></td> <td>2805.5.4</td> <td>Part 5.4:</td> <td>Ciphers – Data Encipherment Algorithm 3 (DEA 3) & related techniques</td> </tr> <tr> <td></td> <td>2805.6.1.1</td> <td>Part 6.1.1:</td> <td>Key Management – Principles</td> </tr> <tr> <td></td> <td>2805.6.1.2</td> <td>Part 6.1.2:</td> <td>Key Management – Symmetric Ciphers, their Key Management & Life Cycle</td> </tr> <tr> <td></td> <td>2805.6.1.4</td> <td>Part 6.1.4:</td> <td>Key Management – Asymmetric Cryptosystems – Key Management & Life Cycle</td> </tr> <tr> <td></td> <td width="81">2805.6.2</td> <td width="90">Part 6.2:</td> <td width="640">Key Management – Transaction keys</td> </tr> <tr> <td></td> <td>2805.6.3</td> <td>Part 6.3:</td> <td>Key Management – Session Keys – Node to Node</td> </tr> <tr> <td></td> <td>2805.6.4</td> <td>Part 6.4:</td> <td>Key Management – Session Keys – Terminal to Acquirer</td> </tr> <tr> <td></td> <td width="81">2805.6.5.1</td> <td width="90">Part 6.5.1:</td> <td width="640">Key Management – TCU Initialisation – Principles</td> </tr> <tr> <td></td> <td>2805.6.5.2</td> <td>Part 6.5.2:</td> <td>Key Management – TCU Initialisation – Symmetric</td> </tr> <tr> <td></td> <td>2805.6.5.3</td> <td>Part 6.5.3:</td> <td>Key Management – TCU Initialisation – Asymmetric</td> </tr> <tr> <td></td> <td>2805.6.6</td> <td>Part 6.6:</td> <td>Key Management – Session Keys – Node to Node with KEK Replacement</td> </tr> <tr> <td></td> <td width="81">2805.9</td> <td width="90">Part 9:</td> <td width="640">Privacy of Communications</td> </tr> <tr> <td></td> <td>2805.10.1</td> <td>Part 10.1:</td> <td>File Transfer Integrity Validation</td> </tr> <tr> <td></td> <td>2805.10.2</td> <td>Part 10.2:</td> <td>Secure File Transfer (Retail)</td> </tr> <tr> <td></td> <td>2805.11</td> <td>Part 11:</td> <td>Card Parameter Table</td> </tr> <tr> <td></td> <td>2805.12.1</td> <td>Part 12.1:</td> <td>Message Content – Structure and Format</td> </tr> <tr> <td></td> <td>2805.12.2</td> <td>Part 12.2:</td> <td>Message Content – Codes</td> </tr> <tr> <td></td> <td>2805.12.3</td> <td>Part 12.3:</td> <td>Message Content – Maintenance of Codes</td> </tr> <tr> <td></td> <td>2805.13.1</td> <td>Part 13.1:</td> <td>Secure Hash Functions – General</td> </tr> <tr> <td></td> <td>2805.13.2</td> <td>Part 13.2:</td> <td>Secure Hash Functions – MD5</td> </tr> <tr> <td></td> <td>2805.13.3</td> <td>Part 13.3:</td> <td>Secure Hash Functions – SHA-1</td> </tr> <tr> <td></td> <td>2805.14.1</td> <td>Part 14.1:</td> <td>Secure Cryptographic Devices (Retail) – Concepts, Requirements and Evaluation Methods</td> </tr> <tr> <td></td> <td>2805.14.2</td> <td>Part 14.2:</td> <td>Secure Cryptographic Devices (Retail) – Security Compliance Checklist for Devices used in Financial Transactions</td> </tr> <tr> <td></td> <td>2805.16</td> <td>Part 16:</td> <td>Merchant Category Codes</td> </tr> </tbody> </table> <p>The AS2805 standard also provides three (3) published Handbooks related to the AS2805 standard:</p> <table border="0" width="900"> <tbody> <tr> <td width="59"></td> <td width="66">HB 127</td> <td width="761">EFT – Implementing Message Content Standards – Conversion Handbook</td> </tr> <tr> <td></td> <td>HB 128</td> <td>EFT – Implementing Message Content Standards – Terminal Handbook</td> </tr> <tr> <td></td> <td>HB 129</td> <td>EFT – Implementing Message Content Standards – Interchange Handbook</td> </tr> </tbody> </table> <p>There are a number of guideline white papers available to assist the implementation of EFT related functionality such as:</p> <ul> <li>Card Management & Production</li> <li>EFTPOS/POS Software Management</li> <li>EFTPOS and POS Product Management</li> <li>Software and Configuration File Downloading</li> <li>Retail Electronic Data Exchange (EDT) that covers price downloads, ordering and statistics</li> <li>Retail Automation</li> <li>Terminal Management</li> <li>Merchant Management</li> <li>Cashier Management</li> <li>Fraud Monitoring and Management</li> </ul> </div> <footer class="entry-footer default-max-width"> <span class="byline"><svg class="svg-icon" width="16" height="16" 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="M15 7.5C15 9.15685 13.6569 10.5 12 10.5C10.3431 10.5 9 9.15685 9 7.5C9 5.84315 10.3431 4.5 12 4.5C13.6569 4.5 15 5.84315 15 7.5ZM16.5 7.5C16.5 9.98528 14.4853 12 12 12C9.51472 12 7.5 9.98528 7.5 7.5C7.5 5.01472 9.51472 3 12 3C14.4853 3 16.5 5.01472 16.5 7.5ZM19.5 19.5V16.245C19.5 14.729 18.271 13.5 16.755 13.5L7.245 13.5C5.72898 13.5 4.5 14.729 4.5 16.245L4.5 19.5H6L6 16.245C6 15.5574 6.5574 15 7.245 15L16.755 15C17.4426 15 18 15.5574 18 16.245V19.5H19.5Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted by</span><span class="author vcard"><a class="url fn n" href="https://arthurvandermerwe.com/author/arthurvdmerwe/">arthurvdmerwe</a></span></span><span class="posted-on"><svg class="svg-icon" width="16" height="16" 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="M19.5 7.5H4.5V19.0005C4.5 19.2764 4.72363 19.5 4.9995 19.5H19.0005C19.2764 19.5 19.5 19.2764 19.5 19.0005V7.5ZM3 7.5V4.9995V4.995C3 3.89319 3.89319 3 4.995 3H4.9995H19.0005H19.005C20.1068 3 21 3.89319 21 4.995V4.9995V7.5V19.0005C21 20.1048 20.1048 21 19.0005 21H4.9995C3.89521 21 3 20.1048 3 19.0005V7.5ZM7.5 10.5H9V12H7.5V10.5ZM9 15H7.5V16.5H9V15ZM11.25 10.5H12.75V12H11.25V10.5ZM12.75 15H11.25V16.5H12.75V15ZM15 10.5H16.5V12H15V10.5ZM16.5 15H15V16.5H16.5V15Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/22/as2805-standards-for-eft/" rel="bookmark"><time class="entry-date published" datetime="2014-06-22T10:28:15+10:00">June 22, 2014</time><time class="updated" datetime="2014-06-22T10:28:57+10:00">June 22, 2014</time></a></span><span class="cat-links"><svg class="svg-icon" width="16" height="16" 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="M12.1979 8.25L11.2098 6.27363C11.1259 6.10593 10.9545 6 10.767 6H4.995C4.72162 6 4.5 6.22162 4.5 6.495V17.505C4.5 17.7784 4.72162 18 4.995 18H19.0005C19.2764 18 19.5 17.7764 19.5 17.5005V8.7495C19.5 8.47363 19.2764 8.25 19.0005 8.25H12.1979ZM13.125 6.75H19.0005C20.1048 6.75 21 7.64521 21 8.7495V17.5005C21 18.6048 20.1048 19.5 19.0005 19.5H4.995C3.89319 19.5 3 18.6068 3 17.505V6.495C3 5.39319 3.89319 4.5 4.995 4.5H10.767C11.5227 4.5 12.2135 4.92693 12.5514 5.60281L13.125 6.75Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted in</span><a href="https://arthurvandermerwe.com/category/financial-switching/" rel="category tag">Financial Switching</a></span><span class="tags-links"><svg class="svg-icon" width="16" height="16" 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="M3 12.2045C3 12.5941 3.15158 12.9684 3.42267 13.2482L9.71878 19.747C11.0769 21.1489 13.3201 21.1667 14.7003 19.7865L19.7873 14.6995C21.1677 13.319 21.1497 11.0753 19.7471 9.71731L13.2459 3.42238C12.9661 3.15147 12.5919 3 12.2025 3H4.5C3.67157 3 3 3.67157 3 4.5V12.2045ZM12.2025 4.5H4.5V12.2045L10.7961 18.7033C11.5714 19.5035 12.8518 19.5137 13.6396 18.7258L18.7266 13.6388C19.5146 12.8509 19.5043 11.5701 18.7037 10.7949L12.2025 4.5ZM8.4975 9.495C9.0484 9.495 9.495 9.0484 9.495 8.4975C9.495 7.9466 9.0484 7.5 8.4975 7.5C7.9466 7.5 7.5 7.9466 7.5 8.4975C7.5 9.0484 7.9466 9.495 8.4975 9.495Z" fill="currentColor"/></svg><span class="screen-reader-text">Tags:</span><a href="https://arthurvandermerwe.com/tag/as2805/" rel="tag">AS2805</a>, <a href="https://arthurvandermerwe.com/tag/australia/" rel="tag">Australia</a>, <a href="https://arthurvandermerwe.com/tag/australia-standards/" rel="tag">Australia Standards</a>, <a href="https://arthurvandermerwe.com/tag/australian-payments-clearing-association/" rel="tag">Australian Payments Clearing Association</a>, <a href="https://arthurvandermerwe.com/tag/message-authentication/" rel="tag">Message Authentication</a></span><span class="comments-link"><svg class="svg-icon" width="16" height="16" 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="M10.0458 15.0001L5.99998 17.697L5.99999 6.49478C5.99999 6.22141 6.2216 5.99979 6.49498 5.99978L17.505 5.99951C17.7784 5.9995 18 6.22113 18 6.49451L18 14.5046C18 14.778 17.7784 14.9996 17.505 14.9996L10.0458 15.0001ZM10.5 16.5L17.5051 16.4996C18.6069 16.4995 19.5 15.6063 19.5 14.5046L19.5 6.49451C19.5 5.39268 18.6068 4.49948 17.5049 4.49951L6.49494 4.49978C5.39315 4.49981 4.49999 5.39299 4.49999 6.49478L4.49998 18.3483C4.49998 18.9842 5.01549 19.4997 5.6514 19.4997C5.8787 19.4997 6.10091 19.4324 6.29004 19.3063L10.5 16.5Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/22/as2805-standards-for-eft/#comments">5 Comments<span class="screen-reader-text"> on AS2805 Standards for EFT</span></a></span> </footer> </article> <article id="post-30" class="post-30 post type-post status-publish format-standard hentry category-financial-switching tag-middleware tag-triton entry"> <header class="entry-header default-max-width"> <h2 class="entry-title"><a href="https://arthurvandermerwe.com/2014/06/22/trace-your-atm-transactions/" rel="bookmark">Trace your ATM Transactions</a></h2> </header> <div class="entry-content"> <h3>Introduction</h3> <p>Generally when entrepreneurs decide to become ATM deployers, they do not have sufficient knowledge about ATM protocols and specifications. This is not needed as there are switching providers that can switch their ATM’s transactions and provide them with adequate reporting.</p> <p>Following this approach generally leaves them with a massive gap in terms of managing their terminals and merchants correctly. ATM switching providers have the ability to decode the terminal status messages in real time and determine for example is a terminal has ran out of cash, if hardware is busy failing or even if a processing bank has gone offline.</p> <p>This allows switching providers to have the upper hand over the smaller ATM deployers.</p> <p>In this post I will show you how to develop a middleware where this pro active approach can be followed even with small ATM deployers. You will be able to see live cash levels of your terminals and monitor ATM transactions.</p> <p> </p> <h3>ATM Languages</h3> <p>ATM’s and EFTPOS devices speak different languages and each terminal manufacturer might have their own custom implementation. Terminal developers normally follow a few types of language implementations: Triton / NDC+ / AS2805 / ISO8583. As all of these will run on TCP using some sort of control protocol (VISAII / ACK Controlled) we need to decode the control elements of the protocol as well.</p> <p>I will be using the Standard Triton Protocol over VISAII to demonstrate the ability to trace transactional protocols.</p> <p>Most ATM’s have an TCP/IP setting that will enable you to point the ATM to an IP Address and port. Writing an Server component to listen to this is of course as easy as pie.</p> <h3>Conversion to ASCII</h3> <p>It is an easy approach to write a server application and listen on a post for incoming transactions but we will quickly notice that these message are encoded. This encoding it an easy hurdle (as long as there is no SSL component on the ATM)</p> <h4>StringToAscii Class – The readable encoding</h4> <p>The first class I’m going to create is an class that can convert encoded strings to readable ascii, this need the be based on the control characters specified in your protocol specification.</p> <p>Each Hex encoded string needs to be mapped to the format you require. (<ETX> / <STX>) and a simple function can provide the conversion.</p> <pre>controls_dic = { 0: '<NUL>', 1: '<SOH>', 2: '<STX>', 3: '<ETX>', 4: '<EOT>', 5: '<ENQ>', 6: '<ACK>', 7: '<BEL>', 8: '<BS>' , 9: '<HT>' , 10: '<LF>' , 11: '<VT>' , 12: '<FF>' , 13: '<CR>' , 14: '<SO>' , 15: '<SI>' , 16: '<DLE>', 17: '<DC1>', 18: '<DC2>', 19: '<DC3>', 20: '<DC4>', 21: '<NAK>', 22: '<SYN>', 23: '<ETB>', 24: '<CAN>', 25: '<EM>', 26: '<SUB>', 27: '<ESC>', 28: '<FS>' , 29: '<GS>' , 30: '<RS>' , 31: '<US>' } def Str2Ascii(s): r = '' for c in s: if ord(c) < 32: r = r + controls_dic[ord(c)] elif ord(c) >= 127: r = r + '<%d>' % ord(c) else: r = r + c return r</pre> <p>The reverse conversion is slightly more complex, but in essence its just a reverse function of the above.</p> <pre>reverse_dic5 = { '<NUL>': 0, '<SOH>': 1, '<STX>': 2, '<ETX>': 3, '<EOT>': 4, '<ENQ>': 5, '<ACK>': 6, '<BEL>': 7, '<DLE>': 16, '<DC1>': 17, '<DC2>': 18, '<DC3>': 19, '<DC4>': 20, '<NAK>': 21, '<SYN>': 22, '<ETB>': 23, '<CAN>': 24, '<SUB>': 26, '<ESC>': 27 } reverse_dic4 = { '<BS>' : 8, '<HT>' : 9, '<LF>' : 10, '<VT>' : 11, '<FF>' : 12, '<CR>' : 13, '<SO>' : 14, '<SI>' : 15, '<EM>' : 25, '<FS>' : 28, '<GS>' : 29, '<RS>' : 30, '<US>' : 31 } reverse_dicN = { '<130>':130, '<140>':140, '<150>':150, '<160>':160, '<170>':170, '<180>':180, '<190>':190, '<200>':200, '<210>':210, '<220>':220, '<230>':230, '<240>':240, '<250>':250, '<131>':131, '<141>':141, '<151>':151, '<161>':161, '<171>':171, '<181>':181, '<191>':191, '<201>':201, '<211>':211, '<221>':221, '<231>':231, '<241>':241, '<251>':251, '<132>':132, '<142>':142, '<152>':152, '<162>':162, '<172>':172, '<182>':182, '<192>':192, '<202>':202, '<212>':212, '<222>':222, '<232>':232, '<242>':242, '<252>':252, '<133>':133, '<143>':143, '<153>':153, '<163>':163, '<173>':173, '<183>':183, '<193>':193, '<203>':203, '<213>':213, '<223>':223, '<233>':233, '<243>':243, '<253>':253, '<134>':134, '<144>':144, '<154>':154, '<164>':164, '<174>':174, '<184>':184, '<194>':194, '<204>':204, '<214>':214, '<224>':224, '<234>':234, '<244>':244, '<254>':254, '<135>':135, '<145>':145, '<155>':155, '<165>':165, '<175>':175, '<185>':185, '<195>':195, '<205>':205, '<215>':215, '<225>':225, '<235>':235, '<245>':245, '<255>':255, '<136>':136, '<146>':146, '<156>':156, '<166>':166, '<176>':176, '<186>':186, '<196>':196, '<206>':206, '<216>':216, '<226>':226, '<236>':236, '<246>':246, '<127>' : 127, '<137>':137, '<147>':147, '<157>':157, '<167>':167, '<177>':177, '<187>':187, '<197>':197, '<207>':207, '<217>':217, '<227>':227, '<237>':237, '<247>':247, '<128>' : 128, '<138>':138, '<148>':148, '<158>':158, '<168>':168, '<178>':178, '<188>':188, '<198>':198, '<208>':208, '<218>':218, '<228>':228, '<238>':238, '<248>':248, '<129>' : 129, '<139>':139, '<149>':149, '<159>':159, '<169>':169, '<179>':179, '<189>':189, '<199>':199, '<209>':209, '<219>':219, '<229>':229, '<239>':239, '<249>':249 } def Ascii2Str(s): r = '' i = 0 l = len(s) while i < l: if s[i] == '<': try: x = reverse_dic5[s[i:i+5]] r = r + chr(x) i = i + 5 except KeyError: try: x = reverse_dic4[s[i:i+4]] r = r + chr(x) i = i + 4 except KeyError: try: x = reverse_dicN[s[i:i+5]] r = r + chr(x) i = i + 5 except KeyError: r = r + s[i] i = i + 1 else: r = r + s[i] i = i + 1 return r</pre> <h3></h3> <p>We can now pass a simulated transaction to the function and test the output and see if the class is correctly implemented acceding to the Triton Standard Protocol.</p> <p>Message</p> <pre>message = '05 02 39 56 44 44 39 30 30 32 32 30 30 30 30 30 32 1C 31 31 1C 30 34 30 36 1C 34 32 31 36 34 36 30 30 30 30 30 30 30 30 30 38 3D 31 34 31 32 31 30 31 31 31 38 38 35 32 34 39 31 32 33 34 35 1C 30 30 30 30 32 30 30 30 1C 30 30 30 30 30 30 30 30 1C 38 36 32 37 42 38 36 33 34 37 41 30 33 37 37 35 1C 1C 1C 1C 5E 35 45 36 32 20 44 35 37 37 1C 03 6E '.replace(" ", "").decode("hex")</pre> <p>Result</p> <pre><ENQ><STX>9U00009D <FS>11<FS>0406<FS>4216460000000008=14121011188524912345<FS>00002000<FS>00000000<FS>8627B86347A03775<FS><FS><FS><FS>^5E62 D577<ETX></pre> <p>Reversing this back to an encoded string we just need to pass it to the ASCIIToString Function of course.</p> <h3>Tracing Data</h3> <p>Now that we have all the field from the request from the ATM, the next step is to create a server component that can run and pass this transactional information to our processing party.</p> <p>Creating a Server is not part of this post, but all source code is available in the gitbub repository. But the basic structure should be that you should create a incoming and sending socket, and poll for connections using a daemon thread. Passing ALL information to the processing party, but saving the requests to the database.</p> <p>Port Listening for ATM connections</p> <pre> self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) self.sock.bind(('', int(listening_port))) self.sock.listen(5)</pre> <p> </p> <p>Port forwarding to Processor with SSL</p> <pre>fwd = socket.socket(socket.AF_INET, socket.SOCK_STREAM) try: ssl_sock = ssl.wrap_socket(fwd) ssl_sock.settimeout(int(session.destination_timeout)) ssl_sock.connect((session.destination_ip, int(session.destination_port))) ssl_sock.do_handshake() self.log.info('SSL Handshake Completed') self.log.debug('%s: Connected to switch %s:%s' % ( session.SessionUUID, session.destination_ip, session.destination_port,)) except socket.timeout: session.error = "Timeout connecting to switch" self.log.critical('%s: EE Cant Connect to %s:%s : %s' % ( session.SessionUUID, session.destination_ip, session.destination_port, session.error,)) ssl_sock.close() except socket.sslerror: session.error = "SSL Error connecting to TNS" self.log.critical('%s: EE Cant Connect to %s:%s : %s' % ( session.SessionUUID, session.destination_ip, session.destination_port, session.error,)) ssl_sock.close() except: session.error = "Unknown Error connecting to switch" self.log.exception('%s: EE Unknown Error Connecting to %s:%s : %s' % ( session.SessionUUID, session.destination_ip, session.destination_port, session.error,)) ssl_sock.close() else: ssl_sock.settimeout(None) RequestThread(session, newsock, ssl_sock).start() ResponseThread(session, ssl_sock, newsock).start()</pre> <p>When a specific Transaction type is received from the ATM you can dissect the readable ascii and save the request to database, when the corresponding session has a response then you can of course save the response information with the request.</p> <p>In my code example I provide the implementation of request and response saving as based on the Triton Specification. If you are using NDC+ or ISO 8583 then this will dramatically change.</p> <h3>Security</h3> <p>The security aspect of this project should be implemented in the raw socket components (SSL Sockets), if there is a need for SSL certificate validation and ACL’s then it should not be difficult to add this to the required class.</p> <p>PCI DSS require us not to store raw Personal Account numbers in the database so we should in fact use a hash function.</p> <p>A simple method for doing this is the following:</p> <pre>return pan[:6] + ("*" * (len(pan)-10)) + pan[-4:]</pre> <h3>Final Product</h3> <p>The final product is a python implementation of a Transactional Middleware. Allot of changes will be required to make the project work for your environment, but here are basic instructions to make it work for you.</p> <ol> <li>Get a clean Linux installation</li> <li>Install the LAMP Stack</li> <li>run the SQL file in the project</li> <li>copy the project directory to the server</li> <li>app_get all the project dependencies. (pymysql ect.)</li> <li>change the config file to point to your database and your switching provider (Middleware.ini)</li> <li>create a screen session (command: screen -S TransactionServer )</li> <li>start the Server in the screen session (sudo python pyMiddlewareServer foreground)</li> </ol> <p>When starting it up you should see the following:</p> <pre>2014-05-24 17:53:38,177 MyDaemon INFO run() Start 2014-05-24 17:53:38,180 Pinhole INFO Redirecting: localhost:9100 -> xxx.xxx.xxx.xx:xxxxx 2014-05-24 17:53:38,263 QueueLogger INFO Connected to Database <_mysql.connection open to '127.0.0.1' at 100837020> 2014-05-24 17:53:45,704 Pinhole INFO 8850226b-e318-11e3-8a9a-28cfe91efd87: NN New Session from ('127.0.0.1', 49660) 2014-05-24 17:53:45,817 Pinhole INFO SSL Handshake Completed 2014-05-24 17:53:45,832 Request INFO 8850226b-e318-11e3-8a9a-28cfe91efd87: > AtmID=[9VDD90022000002], Type=[Authorization from Cheque Account], Operation=[CW] 2014-05-24 17:53:45,832 Request INFO 8850226b-e318-11e3-8a9a-28cfe91efd87: > PAN=[216460000000008] 2014-05-24 17:53:46,072 Request INFO 8850226b-e318-11e3-8a9a-28cfe91efd87: > AtmID=[9VDD90022000002], Type=[Authorization from Cheque Account], Operation=[CW] 2014-05-24 17:53:46,072 Request INFO 8850226b-e318-11e3-8a9a-28cfe91efd87: > PAN=[216460000000008]</pre> <p>Source code: <a href="https://github.com/Arthurvdmerwe/ATM-Transaction-Trace.git">https://github.com/Arthurvdmerwe/ATM-Transaction-Trace.git</a></p> </div> <footer class="entry-footer default-max-width"> <span class="byline"><svg class="svg-icon" width="16" height="16" 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="M15 7.5C15 9.15685 13.6569 10.5 12 10.5C10.3431 10.5 9 9.15685 9 7.5C9 5.84315 10.3431 4.5 12 4.5C13.6569 4.5 15 5.84315 15 7.5ZM16.5 7.5C16.5 9.98528 14.4853 12 12 12C9.51472 12 7.5 9.98528 7.5 7.5C7.5 5.01472 9.51472 3 12 3C14.4853 3 16.5 5.01472 16.5 7.5ZM19.5 19.5V16.245C19.5 14.729 18.271 13.5 16.755 13.5L7.245 13.5C5.72898 13.5 4.5 14.729 4.5 16.245L4.5 19.5H6L6 16.245C6 15.5574 6.5574 15 7.245 15L16.755 15C17.4426 15 18 15.5574 18 16.245V19.5H19.5Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted by</span><span class="author vcard"><a class="url fn n" href="https://arthurvandermerwe.com/author/arthurvdmerwe/">arthurvdmerwe</a></span></span><span class="posted-on"><svg class="svg-icon" width="16" height="16" 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="M19.5 7.5H4.5V19.0005C4.5 19.2764 4.72363 19.5 4.9995 19.5H19.0005C19.2764 19.5 19.5 19.2764 19.5 19.0005V7.5ZM3 7.5V4.9995V4.995C3 3.89319 3.89319 3 4.995 3H4.9995H19.0005H19.005C20.1068 3 21 3.89319 21 4.995V4.9995V7.5V19.0005C21 20.1048 20.1048 21 19.0005 21H4.9995C3.89521 21 3 20.1048 3 19.0005V7.5ZM7.5 10.5H9V12H7.5V10.5ZM9 15H7.5V16.5H9V15ZM11.25 10.5H12.75V12H11.25V10.5ZM12.75 15H11.25V16.5H12.75V15ZM15 10.5H16.5V12H15V10.5ZM16.5 15H15V16.5H16.5V15Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/22/trace-your-atm-transactions/" rel="bookmark"><time class="entry-date published" datetime="2014-06-22T07:29:19+10:00">June 22, 2014</time><time class="updated" datetime="2015-03-10T22:29:45+11:00">March 10, 2015</time></a></span><span class="cat-links"><svg class="svg-icon" width="16" height="16" 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="M12.1979 8.25L11.2098 6.27363C11.1259 6.10593 10.9545 6 10.767 6H4.995C4.72162 6 4.5 6.22162 4.5 6.495V17.505C4.5 17.7784 4.72162 18 4.995 18H19.0005C19.2764 18 19.5 17.7764 19.5 17.5005V8.7495C19.5 8.47363 19.2764 8.25 19.0005 8.25H12.1979ZM13.125 6.75H19.0005C20.1048 6.75 21 7.64521 21 8.7495V17.5005C21 18.6048 20.1048 19.5 19.0005 19.5H4.995C3.89319 19.5 3 18.6068 3 17.505V6.495C3 5.39319 3.89319 4.5 4.995 4.5H10.767C11.5227 4.5 12.2135 4.92693 12.5514 5.60281L13.125 6.75Z" fill="currentColor"/></svg><span class="screen-reader-text">Posted in</span><a href="https://arthurvandermerwe.com/category/financial-switching/" rel="category tag">Financial Switching</a></span><span class="tags-links"><svg class="svg-icon" width="16" height="16" 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="M3 12.2045C3 12.5941 3.15158 12.9684 3.42267 13.2482L9.71878 19.747C11.0769 21.1489 13.3201 21.1667 14.7003 19.7865L19.7873 14.6995C21.1677 13.319 21.1497 11.0753 19.7471 9.71731L13.2459 3.42238C12.9661 3.15147 12.5919 3 12.2025 3H4.5C3.67157 3 3 3.67157 3 4.5V12.2045ZM12.2025 4.5H4.5V12.2045L10.7961 18.7033C11.5714 19.5035 12.8518 19.5137 13.6396 18.7258L18.7266 13.6388C19.5146 12.8509 19.5043 11.5701 18.7037 10.7949L12.2025 4.5ZM8.4975 9.495C9.0484 9.495 9.495 9.0484 9.495 8.4975C9.495 7.9466 9.0484 7.5 8.4975 7.5C7.9466 7.5 7.5 7.9466 7.5 8.4975C7.5 9.0484 7.9466 9.495 8.4975 9.495Z" fill="currentColor"/></svg><span class="screen-reader-text">Tags:</span><a href="https://arthurvandermerwe.com/tag/middleware/" rel="tag">middleware</a>, <a href="https://arthurvandermerwe.com/tag/triton/" rel="tag">triton</a></span><span class="comments-link"><svg class="svg-icon" width="16" height="16" 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="M10.0458 15.0001L5.99998 17.697L5.99999 6.49478C5.99999 6.22141 6.2216 5.99979 6.49498 5.99978L17.505 5.99951C17.7784 5.9995 18 6.22113 18 6.49451L18 14.5046C18 14.778 17.7784 14.9996 17.505 14.9996L10.0458 15.0001ZM10.5 16.5L17.5051 16.4996C18.6069 16.4995 19.5 15.6063 19.5 14.5046L19.5 6.49451C19.5 5.39268 18.6068 4.49948 17.5049 4.49951L6.49494 4.49978C5.39315 4.49981 4.49999 5.39299 4.49999 6.49478L4.49998 18.3483C4.49998 18.9842 5.01549 19.4997 5.6514 19.4997C5.8787 19.4997 6.10091 19.4324 6.29004 19.3063L10.5 16.5Z" fill="currentColor"/></svg><a href="https://arthurvandermerwe.com/2014/06/22/trace-your-atm-transactions/#respond">Leave a comment<span class="screen-reader-text"> on Trace your ATM Transactions</span></a></span> </footer> </article> </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? (Part 5) — A Few Thoughts on Cryptographic Engineering</a> </li> <li> <a href="https://arthurvandermerwe.com/2019/02/21/attack-of-the-week-searchable-encryption-and-the-ever-expanding-leakage-function-a-few-thoughts-on-cryptographic-engineering/">Attack of the week: searchable encryption and the ever-expanding leakage function — A Few Thoughts on Cryptographic Engineering</a> </li> <li> <a href="https://arthurvandermerwe.com/2017/12/29/from-bi-linear-maps-to-searchable-encryption/">From Bi-Linear Maps to Searchable Encryption</a> </li> <li> <a href="https://arthurvandermerwe.com/2017/02/10/mutual-authentication-using-certificates/">Mutual Authentication using Certificates</a> </li> <li> <a href="https://arthurvandermerwe.com/2016/09/04/importing-zpk-and-zmk-into-thales-payshield-9000-hsm/">Importing ZPK and ZMK into Thales Payshield 9000 HSM</a> </li> <li> <a href="https://arthurvandermerwe.com/2016/07/23/signature-and-certificate-based-key-injection-for-atm/">Signature and Certificate based key injection for ATM</a> </li> <li> <a href="https://arthurvandermerwe.com/2015/07/31/the-refund-vulnerability-of-as2805-and-eftpos/">The Refund vulnerability of AS2805 and EFTPOS</a> </li> <li> <a href="https://arthurvandermerwe.com/2015/05/30/dukpt-explained-with-examples/">DUKPT Explained with examples</a> </li> <li> <a href="https://arthurvandermerwe.com/2015/05/28/eftpos-initialisation-using-rsa-cryptography/">EFTPOS Initialisation using RSA Cryptography</a> </li> <li> <a href="https://arthurvandermerwe.com/2015/05/20/atm-pin-encryption-using-3des/">ATM Pin encryption using 3DES</a> </li> <li> <a href="https://arthurvandermerwe.com/2015/03/03/implementing-as2805-part-3-using-a-thales-9000-and-python/">Implementing AS2805 Part 6 Host to Host Encryption using a Thales 9000 and Python</a> </li> <li> <a href="https://arthurvandermerwe.com/2015/01/04/typical-cryptography-in-as2805-explained/">Typical Cryptography in AS2805 Explained</a> </li> <li> <a href="https://arthurvandermerwe.com/2014/12/02/thales-9000-and-as2805-interchange-commands/">Thales 9000 with AS2805 Interchange & RSA EFTPOS Commands.</a> </li> <li> <a href="https://arthurvandermerwe.com/2014/08/06/thales-key-exchange-examples-and-troubleshooting/">Thales Key Exchange Examples and Troubleshooting</a> </li> <li> <a href="https://arthurvandermerwe.com/2014/08/06/testing-dukpt/">Testing DUKPT</a> </li> <li> <a href="https://arthurvandermerwe.com/2014/07/06/parsing-as25058583-messages/">Parsing AS2505/8583 Messages</a> </li> <li> <a href="https://arthurvandermerwe.com/2014/06/25/dynamic-key-exchange-models/">Dynamic Key Exchange Models</a> </li> <li> <a href="https://arthurvandermerwe.com/2014/06/25/doing-pin-translation/">Doing PIN Translation with DUKPT</a> </li> <li> <a href="https://arthurvandermerwe.com/2014/06/25/credit-vs-debit/">Credit vs Debit</a> </li> <li> <a href="https://arthurvandermerwe.com/2014/06/22/as2805-standards-for-eft/">AS2805 Standards for EFT</a> </li> <li> <a href="https://arthurvandermerwe.com/2014/06/22/trace-your-atm-transactions/">Trace your ATM Transactions</a> </li> </ul> </nav></section><section id="archives-6" class="widget widget_archive"><h2 class="widget-title">Archives</h2><nav aria-label="Archives"> <ul> <li><a href='https://arthurvandermerwe.com/2020/02/'>February 2020</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2020/01/'>January 2020</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2019/02/'>February 2019</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2017/12/'>December 2017</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2017/02/'>February 2017</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2016/09/'>September 2016</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2016/07/'>July 2016</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2015/07/'>July 2015</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2015/05/'>May 2015</a> (3)</li> <li><a href='https://arthurvandermerwe.com/2015/03/'>March 2015</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2015/01/'>January 2015</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2014/12/'>December 2014</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2014/08/'>August 2014</a> (2)</li> <li><a href='https://arthurvandermerwe.com/2014/07/'>July 2014</a> (1)</li> <li><a href='https://arthurvandermerwe.com/2014/06/' aria-current="page">June 2014</a> (5)</li> </ul> </nav></section><section id="wpcom_social_media_icons_widget-4" class="widget widget_wpcom_social_media_icons_widget"><h2 class="widget-title">Social</h2><ul><li><a href="https://www.linkedin.com/in/arthur-van-der-merwe-a7a96a27" class="genericon genericon-linkedin" target="_blank"><span class="screen-reader-text">LinkedIn</span></a></li><li><a href="https://github.com/Arthurvdmerwe" class="genericon genericon-github" target="_blank"><span class="screen-reader-text">GitHub</span></a></li></ul></section> </div> </div> <div class="site-info"> <a class="site-name" href="https://arthurvandermerwe.com/" rel="home">Cryptography & Payments</a><span class="comma">,</span> <a href="https://wordpress.com/?ref=footer_website" rel="nofollow">Create a free website or blog at WordPress.com.</a> </div> </footer> </div>  <script src="//0.gravatar.com/js/hovercards/hovercards.min.js?ver=2025087d8bf6c02970a26c6b0c26b0fcfc89796aa30f84307cffd8fd28d2bcca53dd7a" id="grofiles-cards-js"></script> <script id="wpgroho-js-extra"> var WPGroHo = {"my_hash":""}; </script> <script crossorigin='anonymous' type='text/javascript' src='https://s2.wp.com/wp-content/mu-plugins/gravatar-hovercards/wpgroho.js?m=1610363240i'></script> <script> // Initialize and attach hovercards to all gravatars ( function() { function init() { if ( typeof Gravatar === 'undefined' ) { return; } if ( typeof Gravatar.init !== 'function' ) { return; } Gravatar.profile_cb = function ( hash, id ) { WPGroHo.syncProfileData( hash, id ); }; Gravatar.my_hash = WPGroHo.my_hash; Gravatar.init( 'body', '#wp-admin-bar-my-account', { i18n: { 'Edit your profile →': 'Edit your profile →', 'View profile →': 'View profile →', 'Contact': 'Contact', 'Send money': 'Send money', 'Sorry, we are unable to load this Gravatar profile.': 'Sorry, we are unable to load this Gravatar profile.', 'Profile not found.': 'Profile not found.', 'Too Many Requests.': 'Too Many Requests.', 'Internal Server Error.': 'Internal Server Error.', }, } ); } if ( document.readyState !== 'loading' ) { init(); } else { document.addEventListener( 'DOMContentLoaded', init ); } } )(); </script> <div style="display:none"> </div> <div id="actionbar" dir="ltr" style="display: none;" class="actnbr-pub-seedlet actnbr-has-follow actnbr-has-actions"> <ul> <li class="actnbr-btn actnbr-hidden"> <a class="actnbr-action actnbr-actn-follow " href=""> <svg class="gridicon" height="20" width="20" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20"><path clip-rule="evenodd" d="m4 4.5h12v6.5h1.5v-6.5-1.5h-1.5-12-1.5v1.5 10.5c0 1.1046.89543 2 2 2h7v-1.5h-7c-.27614 0-.5-.2239-.5-.5zm10.5 2h-9v1.5h9zm-5 3h-4v1.5h4zm3.5 1.5h-1v1h1zm-1-1.5h-1.5v1.5 1 1.5h1.5 1 1.5v-1.5-1-1.5h-1.5zm-2.5 2.5h-4v1.5h4zm6.5 1.25h1.5v2.25h2.25v1.5h-2.25v2.25h-1.5v-2.25h-2.25v-1.5h2.25z" fill-rule="evenodd"></path></svg> <span>Subscribe</span> </a> <a class="actnbr-action actnbr-actn-following no-display" href=""> <svg class="gridicon" height="20" width="20" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20"><path fill-rule="evenodd" clip-rule="evenodd" d="M16 4.5H4V15C4 15.2761 4.22386 15.5 4.5 15.5H11.5V17H4.5C3.39543 17 2.5 16.1046 2.5 15V4.5V3H4H16H17.5V4.5V12.5H16V4.5ZM5.5 6.5H14.5V8H5.5V6.5ZM5.5 9.5H9.5V11H5.5V9.5ZM12 11H13V12H12V11ZM10.5 9.5H12H13H14.5V11V12V13.5H13H12H10.5V12V11V9.5ZM5.5 12H9.5V13.5H5.5V12Z" fill="#008A20"></path><path class="following-icon-tick" d="M13.5 16L15.5 18L19 14.5" stroke="#008A20" stroke-width="1.5"></path></svg> <span>Subscribed</span> </a> <div class="actnbr-popover tip tip-top-left actnbr-notice" id="follow-bubble"> <div class="tip-arrow"></div> <div class="tip-inner actnbr-follow-bubble"> <ul> <li class="actnbr-sitename"> <a href="https://arthurvandermerwe.com"> <img loading='lazy' alt='' src='https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=50' srcset='https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=50 1x, https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=75 1.5x, https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=100 2x, https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=150 3x, https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=200 4x' class='avatar avatar-50' height='50' width='50' /> Cryptography & Payments </a> </li> <div class="actnbr-message no-display"></div> <form method="post" action="https://subscribe.wordpress.com" accept-charset="utf-8" style="display: none;"> <div class="actnbr-follow-count">Join 30 other subscribers</div> <div> <input type="email" name="email" placeholder="Enter your email address" class="actnbr-email-field" aria-label="Enter your email address" /> </div> <input type="hidden" name="action" value="subscribe" /> <input type="hidden" name="blog_id" value="70204527" /> <input type="hidden" name="source" value="https://arthurvandermerwe.com/2014/06/" /> <input type="hidden" name="sub-type" value="actionbar-follow" /> <input type="hidden" id="_wpnonce" name="_wpnonce" value="fcb1f8d0bf" /> <div class="actnbr-button-wrap"> <button type="submit" value="Sign me up"> Sign me up </button> </div> </form> <li class="actnbr-login-nudge"> <div> Already have a WordPress.com account? <a href="https://wordpress.com/log-in?redirect_to=https%3A%2F%2Fr-login.wordpress.com%2Fremote-login.php%3Faction%3Dlink%26back%3Dhttps%253A%252F%252Farthurvandermerwe.com%252F2014%252F06%252F25%252Fdynamic-key-exchange-models%252F">Log in now.</a> </div> </li> </ul> </div> </div> </li> <li class="actnbr-ellipsis actnbr-hidden"> <svg class="gridicon gridicons-ellipsis" height="24" width="24" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><g><path d="M7 12c0 1.104-.896 2-2 2s-2-.896-2-2 .896-2 2-2 2 .896 2 2zm12-2c-1.104 0-2 .896-2 2s.896 2 2 2 2-.896 2-2-.896-2-2-2zm-7 0c-1.104 0-2 .896-2 2s.896 2 2 2 2-.896 2-2-.896-2-2-2z"/></g></svg> <div class="actnbr-popover tip tip-top-left actnbr-more"> <div class="tip-arrow"></div> <div class="tip-inner"> <ul> <li class="actnbr-sitename"> <a href="https://arthurvandermerwe.com"> <img loading='lazy' alt='' src='https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=50' srcset='https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=50 1x, https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=75 1.5x, https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=100 2x, https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=150 3x, https://arthurvandermerwe.com/wp-content/uploads/2018/09/cropped-arthur4.png?w=200 4x' class='avatar avatar-50' height='50' width='50' /> Cryptography & Payments </a> </li> <li class="actnbr-folded-follow"> <a class="actnbr-action actnbr-actn-follow " href=""> <svg class="gridicon" height="20" width="20" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20"><path clip-rule="evenodd" d="m4 4.5h12v6.5h1.5v-6.5-1.5h-1.5-12-1.5v1.5 10.5c0 1.1046.89543 2 2 2h7v-1.5h-7c-.27614 0-.5-.2239-.5-.5zm10.5 2h-9v1.5h9zm-5 3h-4v1.5h4zm3.5 1.5h-1v1h1zm-1-1.5h-1.5v1.5 1 1.5h1.5 1 1.5v-1.5-1-1.5h-1.5zm-2.5 2.5h-4v1.5h4zm6.5 1.25h1.5v2.25h2.25v1.5h-2.25v2.25h-1.5v-2.25h-2.25v-1.5h2.25z" fill-rule="evenodd"></path></svg> <span>Subscribe</span> </a> <a class="actnbr-action actnbr-actn-following no-display" href=""> <svg class="gridicon" height="20" width="20" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20"><path fill-rule="evenodd" clip-rule="evenodd" d="M16 4.5H4V15C4 15.2761 4.22386 15.5 4.5 15.5H11.5V17H4.5C3.39543 17 2.5 16.1046 2.5 15V4.5V3H4H16H17.5V4.5V12.5H16V4.5ZM5.5 6.5H14.5V8H5.5V6.5ZM5.5 9.5H9.5V11H5.5V9.5ZM12 11H13V12H12V11ZM10.5 9.5H12H13H14.5V11V12V13.5H13H12H10.5V12V11V9.5ZM5.5 12H9.5V13.5H5.5V12Z" fill="#008A20"></path><path class="following-icon-tick" d="M13.5 16L15.5 18L19 14.5" stroke="#008A20" stroke-width="1.5"></path></svg> <span>Subscribed</span> </a> </li> <li class="actnbr-signup"><a href="https://wordpress.com/start/">Sign up</a></li> <li class="actnbr-login"><a href="https://wordpress.com/log-in?redirect_to=https%3A%2F%2Fr-login.wordpress.com%2Fremote-login.php%3Faction%3Dlink%26back%3Dhttps%253A%252F%252Farthurvandermerwe.com%252F2014%252F06%252F25%252Fdynamic-key-exchange-models%252F">Log in</a></li> <li class="flb-report"> <a href="https://wordpress.com/abuse/?report_url=https://arthurvandermerwe.com" target="_blank" rel="noopener noreferrer"> Report this content </a> </li> <li class="actnbr-reader"> <a href="https://wordpress.com/reader/feeds/22152776"> View site in Reader </a> </li> <li class="actnbr-subs"> <a href="https://subscribe.wordpress.com/">Manage subscriptions</a> </li> <li class="actnbr-fold"><a href="">Collapse this bar</a></li> </ul> </div> </div> </li> </ul> </div> <script> window.addEventListener( "load", function( event ) { var link = document.createElement( "link" ); link.href = "https://s0.wp.com/wp-content/mu-plugins/actionbar/actionbar.css?v=20250116"; link.type = "text/css"; link.rel = "stylesheet"; document.head.appendChild( link ); var script = document.createElement( "script" ); script.src = "https://s0.wp.com/wp-content/mu-plugins/actionbar/actionbar.js?v=20250204"; script.defer = true; document.body.appendChild( script ); } ); </script> <link crossorigin='anonymous' rel='stylesheet' id='all-css-0-2' href='https://s2.wp.com/_static/??-eJyNzDEOgzAMheELNTUZQF2qHgVFjhWZJk5UO0K9fYtgZGB7//A+WJvDKkZiULpruScWhYWsBXwfDdoFZhaEREIf/h/0fN5R9QaXzVJjz6SwckxkClqRQ3aFIge322rfTBv7Kk8/PUbvx2Ealh973US5&cssminify=yes' type='text/css' media='all' /> <script id="custom-content-types-data-js-before"> var CUSTOM_CONTENT_TYPE__INITIAL_STATE; typeof CUSTOM_CONTENT_TYPE__INITIAL_STATE === "object" || (CUSTOM_CONTENT_TYPE__INITIAL_STATE = JSON.parse(decodeURIComponent("%7B%22active%22%3Atrue%2C%22over_ride%22%3Afalse%7D"))); </script> <script crossorigin='anonymous' type='text/javascript' src='https://s0.wp.com/_static/??/wp-content/js/mobile-useragent-info.js,/wp-content/blog-plugins/wordads-classes/js/watl.js,/wp-content/themes/pub/seedlet/assets/js/primary-navigation.js?m=1737553111j'></script> <script> /(trident|msie)/i.test(navigator.userAgent)&&document.getElementById&&window.addEventListener&&window.addEventListener("hashchange",function(){var t,e=location.hash.substring(1);/^[A-z0-9_-]+$/.test(e)&&(t=document.getElementById(e))&&(/^(?:a|select|input|button|textarea)$/i.test(t.tagName)||(t.tabIndex=-1),t.focus())},!1); </script> <script type="text/javascript"> (function () { var wpcom_reblog = { source: 'toolbar', toggle_reblog_box_flair: function (obj_id, post_id) { // Go to site selector. This will redirect to their blog if they only have one. const postEndpoint = `https://wordpress.com/post`; // Ideally we would use the permalink here, but fortunately this will be replaced with the // post permalink in the editor. const originalURL = `${ document.location.href }?page_id=${ post_id }`; const url = postEndpoint + '?url=' + encodeURIComponent( originalURL ) + '&is_post_share=true' + '&v=5'; const redirect = function () { if ( ! window.open( url, '_blank' ) ) { location.href = url; } }; if ( /Firefox/.test( navigator.userAgent ) ) { setTimeout( redirect, 0 ); } else { redirect(); } }, }; window.wpcom_reblog = wpcom_reblog; })(); </script> <script src="//stats.wp.com/w.js?68" defer></script> <script type="text/javascript"> _tkq = window._tkq || []; _stq = window._stq || []; _tkq.push(['storeContext', {'blog_id':'70204527','blog_tz':'11','user_lang':'en','blog_lang':'en','user_id':'0'}]); _stq.push(['view', {'blog':'70204527','v':'wpcom','tz':'11','user_id':'0','subd':'arthurvandermerwe'}]); _stq.push(['extra', {'crypt':'UE5VTUIlVktzQVNtcFdrRlVoJUNZcTJRQnxOUXcyQXBGVjdTZVlnSlY3P0dzcjlxYzIrNExdSDFwWT1HLEN1ZUpvZWZWfnIxLnNwSG1MMjB6UkUwTHhYWTFIXTNvS09YZHJZMldkd2NZc29WcFBsLUg5OFd+LjlqRitoeW1beUdsOVZkWmpFNmcycVdZdEN6VExrUjBQfDg1bXpDKz9IdHVqfmFYcDh6MF04TEdETE1nWX4wYy5jUVBOfC9DcS1kaGowbXBkJkZ1UjROZ104OCY4T01YVVJOZGIuczJ4b3VpVzNzYSw='}]); _stq.push([ 'clickTrackerInit', '70204527', '0' ]); </script> <noscript><img src="https://pixel.wp.com/b.gif?v=noscript" style="height:1px;width:1px;overflow:hidden;position:absolute;bottom:1px;" alt="" /></noscript> <script defer id="bilmur" data-customproperties="{"logged_in":"0","wptheme":"pub\/seedlet","wptheme_is_block":"0"}" data-provider="wordpress.com" data-service="simple" src="/wp-content/js/bilmur-3-4-combined.min.js?i=12&m=202508"></script><script> ( function() { function getMobileUserAgentInfo() { if ( typeof wpcom_mobile_user_agent_info === 'object' ) { wpcom_mobile_user_agent_info.init(); var mobileStatsQueryString = ''; if ( wpcom_mobile_user_agent_info.matchedPlatformName !== false ) { mobileStatsQueryString += '&x_' + 'mobile_platforms' + '=' + wpcom_mobile_user_agent_info.matchedPlatformName; } if ( wpcom_mobile_user_agent_info.matchedUserAgentName !== false ) { mobileStatsQueryString += '&x_' + 'mobile_devices' + '=' + wpcom_mobile_user_agent_info.matchedUserAgentName; } if ( wpcom_mobile_user_agent_info.isIPad() ) { mobileStatsQueryString += '&x_' + 'ipad_views' + '=' + 'views'; } if ( mobileStatsQueryString != '' ) { new Image().src = document.location.protocol + '//pixel.wp.com/g.gif?v=wpcom-no-pv' + mobileStatsQueryString + '&baba=' + Math.random(); } } } document.addEventListener( 'DOMContentLoaded', getMobileUserAgentInfo ); } )(); </script> </body> </html>