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>Authorization transaction – 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=170' + '&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=1732724597"; 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='//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/" /> <link rel="alternate" type="application/rss+xml" title="Cryptography & Payments » Authorization transaction Tag Feed" href="https://arthurvandermerwe.com/tag/authorization-transaction/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=6.8-alpha-59438"}}; /*! 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://s0.wp.com/_static/??-eJydzMsOwiAQheEXEibEXtKF8VmATggVgcwMNby91U13LlyenHw/vKryJQtmgZpaiJkhtGM6pHA8hLCbRU96ANdiWsGl4h8qRUeWOrD0hNozX+Bn6KsYNpRqP9z20kQFiuu/CbISc+CT3583M1/NMg6zGbc3O1tP4A==&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=1720456615j&cssminify=yes' type='text/css' media='all' /> <link crossorigin='anonymous' rel='stylesheet' id='print-css-13-1' href='https://s2.wp.com/wp-content/themes/pub/seedlet/assets/css/print.css?m=1603804565i&cssminify=yes' type='text/css' media='print' /> <link crossorigin='anonymous' rel='stylesheet' id='all-css-14-1' href='https://s0.wp.com/_static/??-eJx9y0EOwjAMRNELYQyiBbFAnKU1JgQ5dlQ7qnp7yq5s2M2X5uFcgUyDNTBeXNixthGd+SEcmJVwrmQFPBbhPbnvcENKgyotZXWceBRL60y4vjb5DyU2EKMhsulPwFOGPH3pvdyO/bU7dOdLf3p/AANwQOQ=&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-16-1' 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":"fe839908c7","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\/read\">Reader<\/a>","foldBar":"Collapse this bar","unfoldBar":"Expand this bar"}}; </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\/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="Authorization transaction – Cryptography & Payments" /> <meta property="og:url" content="https://arthurvandermerwe.com/tag/authorization-transaction/" /> <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="application-name" content="Cryptography & Payments" /><meta name="msapplication-window" content="width=device-width;height=device-height" /><meta name="msapplication-tooltip" content="Arthur Van Der Merwe" /><meta name="description" content="Posts about Authorization transaction written by arthurvdmerwe" /> <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, 'adflow_enabled': true, 'format_id': 135099 }, 'inline': { 'enabled': false, 'adflow_enabled': true, 'format_id': 110354, 'max_slots': 20, 'max_blaze_slots': 20 }, 'belowpost': { 'enabled': false, 'adflow_enabled': true, 'format_id': 134071 }, 'bottom_sticky': { 'enabled': false, 'adflow_enabled': true, 'format_id': 117571 }, 'sidebar': { 'enabled': false, 'adflow_enabled': true, 'format_id': 134686 }, 'sidebar_sticky_right': { 'enabled': false, 'adflow_enabled': true, 'format_id': 135281 }, 'gutenberg_rectangle': { 'enabled': false, 'adflow_enabled': true, 'format_id': 134788 }, 'gutenberg_leaderboard': { 'enabled': false, 'adflow_enabled': true, 'format_id': 135073 }, 'gutenberg_mobile_leaderboard': { 'enabled': false, 'adflow_enabled': true, 'format_id': 135098 }, 'gutenberg_skyscraper': { 'enabled': false, 'adflow_enabled': true, 'format_id': 135088 } }; 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 tag tag-authorization-transaction tag-380424238 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">Tag Archives: </span><span class="page-description">Authorization transaction</span></h1> </header> <article id="post-170" class="post-170 post type-post status-publish format-standard hentry category-financial-switching tag-authorization-transaction tag-eftpos tag-transaction entry"> <header class="entry-header default-max-width"> <h2 class="entry-title"><a href="https://arthurvandermerwe.com/2015/07/31/the-refund-vulnerability-of-as2805-and-eftpos/" rel="bookmark">The Refund vulnerability of AS2805 and EFTPOS</a></h2> </header> <div class="entry-content"> <p>Transactions are normally validated, matched then processed. This is very common to ensure that requests sent to a payments switch are associated with its responses before delivering responses to a terminal. Now for all transaction types this process in true, except for refunds. Well, at least it’s not matched for most financial institutions in Australia.</p> <p>Below is a few descriptions of transactions that might be processed through a typical switch in Australia:</p> <hr /> <p> </p> <p><b>Authorization / Cash Out</b></p> <p>The Authorization transaction is typically used by a merchant to obtain the authorization of a transaction amount as a pre-approval for the purchase of goods or services later during the fulfillment process. Authorization transactions are typically submitted for authorization and then funds are held by the issuer until that transaction is captured or the authorization is reversed or expires. An example can be found with online retailers who initiate an Authorization transaction to guaranteed funding by the card issuer prior to the shipment/delivery (i.e. fulfillment) of the goods. An “Authorization” is also referred to as an Auth-Only transaction.</p> <p><b>Sale / Purchase</b></p> <p>A “Sale” transaction is used by merchants for the immediate purchase of goods or services. This transaction completes both the authorization and capture in a single transaction request. The Sale transaction is an Authorization and Capture transaction that if approved is automatically included for settlement.</p> <hr /> <p> </p> <p><b>Forced Sale</b></p> <p>A “Forced Sale” is a transaction initiated by a merchant with the intent of forcing the posting of the transaction against the customer account without receiving prior authorization by the card issuer, or receiving a voice authorization code from the merchant acquiring call center. An example would be when a merchant’s terminal is offline, requiring the purchase of goods being completed without receiving online authorization by the card issuer. Or they received a Voice Approval. In these cases the merchant would enter the transaction details and forward this Forced Sale transaction to the card issuer with the expectation of receiving funding for the goods or services rendered. A forced sale does not require a matching authorization. Forced Sales are also known as Off-Line Sales.</p> <p><b>Refund</b></p> <p>A Refund allows a merchant to refund a previously settled transaction and submit the refund for processing. Refunds are only allowed for financial transactions (Sale and Captured) and are typically limited to the original authorization amount, or a lesser amount, in some cases, multiple partial refunds up to the original transaction amount. Some systems incorporate a feature called Matched Refunds. Matched Refunds must match back to an original transaction to help control fraud. “ Refunds” are also sometimes referred to as a “Credit” transaction.</p> <p><b>Void</b></p> <p>Void transactions can reverse transactions that have been previously authorized or approved by the card issuer and are pending settlement. Merchants will only be allowed to void transactions that are in an open batch (pending settlement). Sale or Refund transactions are the most commonly voided transaction types.</p> <p><b>Capture</b></p> <p>The Capture transaction will allow merchants to capture a previously authorized transaction that is pending settlement, and submit it for clearing and settlement. An example is when online retailers who initiate an Authorization transaction to reserve funds by the card issuer prior to the shipment/delivery (i.e. fulfillment) of the goods, and then once fulfillment has been completed the transaction will be captured and submitted for settlement. A “Capture” is also referred to as a Pre-Authorization Completion transaction.</p> <hr /> <p> </p> <p>Now According to the AS2805 Specifications, The refund is not matched to the transaction during the refund authorization, and will approve by default, you need to match the Refund to an Authorization or Sale when doing settlement.</p> <p>This appears not implemented in Australia for some reason, and some financial institutions will actually admit it.</p> <p>I have tried this on a EFTPOS machine, you should try this as well. Simply do a refund on a EFTPOS terminal without doing a transaction. All you would need is a 4 digit password to access the refund function (in some cases refunds are not password protected) , these default passwords are published by the terminal manufacturers.</p> <p>In every case that I’ve tried this, the refund is processed and the funds appeared in my account. This is surely a massive risk for fraud!!!!</p> <p>Strange enough, the banks are not worried about this as the funds are tied to the merchant account, and it’s not a risk for the bank but for the Merchant. These are some clause in the contracts that absolve them from the risk.</p> <p>So if you have a EFTPOS terminal, ask for the refund function to be disabled or you could be out of pocket!</p> <p> </p> <p> </p> <div id="atatags-702045271-674747751332a"></div> <script> __ATA.cmd.push(function() { __ATA.initDynamicSlot({ id: 'atatags-702045271-674747751332a', 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/2015/07/31/the-refund-vulnerability-of-as2805-and-eftpos/" rel="bookmark"><time class="entry-date published" datetime="2015-07-31T11:58:56+10:00">July 31, 2015</time><time class="updated" datetime="2018-09-25T22:33:55+10:00">September 25, 2018</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/authorization-transaction/" rel="tag">Authorization transaction</a>, <a href="https://arthurvandermerwe.com/tag/eftpos/" rel="tag">EFTPOS</a>, <a href="https://arthurvandermerwe.com/tag/transaction/" rel="tag">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/2015/07/31/the-refund-vulnerability-of-as2805-and-eftpos/#comments">3 Comments<span class="screen-reader-text"> on The Refund vulnerability of AS2805 and EFTPOS</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/'>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_blog" rel="nofollow">Blog at WordPress.com.</a> </div> </footer> </div>  <script src="//0.gravatar.com/js/hovercards/hovercards.min.js?ver=202448bd3d6792c97e42a81a9d5a5ba6e667b110f2a7530429ac15d169784a739a4e3d" 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', '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" style="display: none;" class="actnbr-pub-seedlet actnbr-has-follow"> <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/tag/authorization-transaction/" /> <input type="hidden" name="sub-type" value="actionbar-follow" /> <input type="hidden" id="_wpnonce" name="_wpnonce" value="65c8d46265" /> <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%252F2015%252F07%252F31%252Fthe-refund-vulnerability-of-as2805-and-eftpos%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-customize"> <a href="https://arthurvandermerwe.wordpress.com/wp-admin/customize.php?url=https%3A%2F%2Farthurvandermerwe.wordpress.com%2Ftag%2Fauthorization-transaction%2F"> <svg class="gridicon gridicons-customize" height="20" width="20" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><g><path d="M2 6c0-1.505.78-3.08 2-4 0 .845.69 2 2 2 1.657 0 3 1.343 3 3 0 .386-.08.752-.212 1.09.74.594 1.476 1.19 2.19 1.81L8.9 11.98c-.62-.716-1.214-1.454-1.807-2.192C6.753 9.92 6.387 10 6 10c-2.21 0-4-1.79-4-4zm12.152 6.848l1.34-1.34c.607.304 1.283.492 2.008.492 2.485 0 4.5-2.015 4.5-4.5 0-.725-.188-1.4-.493-2.007L18 9l-2-2 3.507-3.507C18.9 3.188 18.225 3 17.5 3 15.015 3 13 5.015 13 7.5c0 .725.188 1.4.493 2.007L3 20l2 2 6.848-6.848c1.885 1.928 3.874 3.753 5.977 5.45l1.425 1.148 1.5-1.5-1.15-1.425c-1.695-2.103-3.52-4.092-5.448-5.977z"/></g></svg> <span>Customize</span> </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%252F2015%252F07%252F31%252Fthe-refund-vulnerability-of-as2805-and-eftpos%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/read/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=20241015"; 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=20231122"; 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 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=1731430359j'></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 type="text/javascript"> // <![CDATA[ (function() { try{ if ( window.external &&'msIsSiteMode' in window.external) { if (window.external.msIsSiteMode()) { var jl = document.createElement('script'); jl.type='text/javascript'; jl.async=true; jl.src='/wp-content/plugins/ie-sitemode/custom-jumplist.php'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(jl, s); } } }catch(e){} })(); // ]]> </script><script src="//stats.wp.com/w.js?67" 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':'UE5VTUIlVktzQVNtcFdrRlVoJUNZcTJRQnxOUXcyQXBGVjdTZVlnSlY3P0dzcjlxYzIrNExdSDFwWT1HLEN1ZUpvZWZWfnIxLnNwSG1MMjB6UkUwTDVYQ3NBXWFfVCVtPzdmeVBoJURZTmJRPW5TQkhWeGIyeGY0MENXajQ/fDJ6SEZ8QkFNZGFvUXdmczgxMTVyK3cuQVk/TGlORH5nZVlVQUwlSWxOLTZMeHFJdXhTbk1XW115Xy1oSUUscXVibj8vcl00OHhBX0gvLmolSnkrUUJiKzdPL1FwdjExQ2FQQndpcA=='}]); _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> ( 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>