{"id":10465,"date":"2023-08-02T08:38:08","date_gmt":"2023-08-02T08:38:08","guid":{"rendered":"https:\/\/www.bitnovo.com\/blog\/?p=10465"},"modified":"2022-05-17T08:00:31","modified_gmt":"2022-05-17T08:00:31","slug":"what-are-the-blind-signatures","status":"publish","type":"post","link":"https:\/\/www.bitnovo.com\/blog\/en\/what-are-the-blind-signatures","title":{"rendered":"What are blind signatures?"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 counter-hierarchy ez-toc-counter ez-toc-transparent ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Alternar tabla de contenidos\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #ffffff;color:#ffffff\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #ffffff;color:#ffffff\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 eztoc-toggle-hide-by-default' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.bitnovo.com\/blog\/en\/what-are-the-blind-signatures\/#definition_of_blind_signature\" >Definition of blind signature\u00a0<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.bitnovo.com\/blog\/en\/what-are-the-blind-signatures\/#how_do_blind_signatures_work\" >How do blind signatures work?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.bitnovo.com\/blog\/en\/what-are-the-blind-signatures\/#blind_signatures_in_cryptocurrency_transactions\" >Blind signatures in cryptocurrency transactions<\/a><\/li><\/ul><\/nav><\/div>\n<span class=\"span-reading-time rt-reading-time\" style=\"display: block;\"><span class=\"rt-label rt-prefix\">Tiempo de lectura:<\/span> <span class=\"rt-time\"> 3<\/span> <span class=\"rt-label rt-postfix\">minutos<\/span><\/span><p>Have you ever wondered how some countries have managed to use electronic voting while guaranteeing voter anonymity? And how digital currencies such as\u00a0<a href=\"https:\/\/www.bitnovo.com\/\">bitcoin<\/a>\u00a0manage to\u00a0<strong>carry out verified transactions without knowing who the senders and recipients are?\u00a0<\/strong><\/p>\n<p>The answer lies in the so-called \u2018<strong>blind signatures<\/strong>\u2018, and today you will discover how they work and how they are applied in real cases such as voting or in cryptocurrency transactions.<\/p>\n<div class=\"is-divider divider clearfix\"><\/div>\n<div class=\"is-divider divider clearfix\"><\/div>\n<div class=\"col small-12 large-12\">\n<div class=\"col-inner\">\n<h2><span class=\"ez-toc-section\" id=\"definition_of_blind_signature\"><\/span><strong>Definition of blind signature\u00a0<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<div class=\"is-divider divider clearfix\"><\/div>\n<p>Blind signatures are a technology\u00a0<strong>introduced by David Chaum in 1982<\/strong>, known as a pioneer in cryptography and privacy preservation technologies, and as the\u00a0<strong>inventor of digital cash<\/strong>.<\/p>\n<p><b>They are based on public key digital signature schemes,\u00a0<\/b>such as RSA.<\/p>\n<p>The RSA system guarantees the confidentiality of communication between two parties by encrypting the message to be transmitted over a channel at source and decrypting it on reception. It guarantees the security of the information (authentication of origin, integrity or non-repudiation) by means of the\u00a0<strong>digital signature<\/strong>.<\/p>\n<p>So, the main objective of blind signatures is to get the signer to sign the message without revealing the message itself. This is achieved by\u00a0<strong>disguising or blinding the content<\/strong>\u00a0of the message before signing it.<\/p>\n<p>The resulting blind signature can be publicly verified with the original unblinded message, in the form of a regular digital signature.<\/p>\n<\/div>\n<\/div>\n<div class=\"is-divider divider clearfix\"><\/div>\n<div class=\"is-divider divider clearfix\"><\/div>\n<div class=\"col small-12 large-12\">\n<div class=\"col-inner text-center\">\n<h2><span class=\"ez-toc-section\" id=\"how_do_blind_signatures_work\"><\/span>How do blind signatures work?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<div class=\"is-divider divider clearfix\"><\/div>\n<div id=\"row-1698361139\" class=\"row\">\n<div class=\"col small-12 large-12\">\n<div class=\"col-inner text-center\">\n<div id=\"image_603491388\" class=\"img has-hover x md-x lg-x y md-y lg-y\">\n<div class=\"img-inner dark\"><img fetchpriority=\"high\" decoding=\"async\" class=\"attachment-large size-large lazyloaded\" src=\"https:\/\/www.bitnovo.com\/blog\/wp-content\/uploads\/2021\/04\/Qu%C3%A9-son-las-firmas-ciegas1.jpg\" sizes=\"(max-width: 768px) 100vw, 768px\" srcset=\"https:\/\/www.bitnovo.com\/blog\/wp-content\/uploads\/2021\/04\/Qu\u00e9-son-las-firmas-ciegas1.jpg 768w, https:\/\/www.bitnovo.com\/blog\/wp-content\/uploads\/2021\/04\/Qu\u00e9-son-las-firmas-ciegas1-300x205.jpg 300w\" alt=\"voto electr\u00f3nico\" width=\"768\" height=\"526\" data-srcset=\"https:\/\/www.bitnovo.com\/blog\/wp-content\/uploads\/2021\/04\/Qu\u00e9-son-las-firmas-ciegas1.jpg 768w, https:\/\/www.bitnovo.com\/blog\/wp-content\/uploads\/2021\/04\/Qu\u00e9-son-las-firmas-ciegas1-300x205.jpg 300w\" data-src=\"https:\/\/www.bitnovo.com\/blog\/wp-content\/uploads\/2021\/04\/Qu\u00e9-son-las-firmas-ciegas1.jpg\" data-sizes=\"(max-width: 768px) 100vw, 768px\" \/><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"is-divider divider clearfix\"><\/div>\n<p>David Chaum explained that every time a purchase is made with electronic money and a payment is made, all the information goes into a database, violating our right to privacy.<\/p>\n<p>Hence\u00a0<strong>the need to mask or blind the information in a message by means of a \u201cblind signature\u201d.<\/strong><\/p>\n<p>To explain how a blind signature works, David Chaum uses as an example\u00a0<strong>the voting system<\/strong>, based on the use of envelopes lined with carbon paper. The system works like this:<\/p>\n<ul>\n<li aria-level=\"1\">A voter encloses a completed anonymous ballot in a special envelope lined with carbon paper that has the voter\u2019s credentials pre-printed on the outside.<\/li>\n<li aria-level=\"1\">An official verifies the credentials and signs the envelope, thus transferring his signature to the ballot inside through carbon paper.<\/li>\n<li aria-level=\"1\">Once signed, the package is returned to the voter, who transfers the signed ballot to a new plain, unmarked envelope.<\/li>\n<li aria-level=\"1\">Then, the signer does not see the content of the message, but a third party can subsequently verify the signature and know that the signature is valid within the constraints of the underlying signature scheme.<\/li>\n<\/ul>\n<p><b>Electronic voting has been one of the main use cases<\/b>\u00a0for blind signatures.<\/p>\n<p>Currently the only countries that use electronic voting with legal validity are Belgium, Brazil, Estonia, USA, Philippines, India and Venezuela.<\/p>\n<div class=\"is-divider divider clearfix\"><\/div>\n<div class=\"is-divider divider clearfix\"><\/div>\n<h2><span class=\"ez-toc-section\" id=\"blind_signatures_in_cryptocurrency_transactions\"><\/span>Blind signatures in cryptocurrency transactions<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/div>\n<\/div>\n<div class=\"col small-12 large-12\">\n<div class=\"col-inner\">\n<div class=\"is-divider divider clearfix\"><\/div>\n<p>One of the purposes of cryptocurrencies is to create a payment system that takes care of the privacy of its users.<\/p>\n<p>EIn 1988, David Chaum published an article entitled \u201c<strong>The Dining cryptographers problem: unconditional sender and recipient untraceability<\/strong>\u201c, in which, for the first time, the concepts of \u201c<strong>public key<\/strong>\u201d were discussed.<\/p>\n<p>So, to understand blind signatures, it is important to know\u00a0<strong>how public key cryptography works<\/strong>\u00a0and what cryptographic signatures are.<\/p>\n<p>Public key cryptography uses a\u00a0<strong>public key<\/strong>\u00a0consisting of a random string of numbers that is derived from another random string of numbers: t<strong>he private key<\/strong>. With the private key it is possible to determine the public key. But if we have only the public key, it is practically impossible to generate the private key.<\/p>\n<p>With this type of cryptography, a private communication can be established between two persons<strong>\u00a0A and B , who only share their public keys<\/strong>\u00a0with each other but their private keys remain private.<\/p>\n<p><b>In the world of cryptography a blind signature is a digital signature in which the content of a message is hidden before signing it.\u00a0<\/b><\/p>\n<p>To understand it better we use the example of a user B who, when making a transaction, generates a random number that mathematically combines with the data he wants to send. This data is encoded as a string of random numbers and user B will pass this data to user A for signature.<\/p>\n<p>Since user A cannot know what the original data looks like, he is \u201csigning it blindly\u201d and is therefore called a \u201cblind signature\u201d.<\/p>\n<p><b>What characterizes the blind signature is that it is not only linked to the encrypted data but also to the original unencrypted data.\u00a0<\/b><\/p>\n<p>In this way, the anonymity and privacy of all users performing digital transactions can be preserved.<\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p><span class=\"span-reading-time rt-reading-time\" style=\"display: block;\"><span class=\"rt-label rt-prefix\">Tiempo de lectura:<\/span> <span class=\"rt-time\"> 3<\/span> <span class=\"rt-label rt-postfix\">minutos<\/span><\/span>Have you ever wondered how some countries have managed to use electronic voting while guaranteeing voter anonymity? And how digital currencies such as\u00a0bitcoin\u00a0manage to\u00a0carry out verified transactions without knowing who the senders and recipients are?\u00a0 The answer lies in the so-called \u2018blind signatures\u2018, and today you will discover how they work and how they are [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":7920,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[185],"tags":[],"class_list":["post-10465","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blockchain-en"],"_links":{"self":[{"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/posts\/10465","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/comments?post=10465"}],"version-history":[{"count":0,"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/posts\/10465\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/media\/7920"}],"wp:attachment":[{"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/media?parent=10465"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/categories?post=10465"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bitnovo.com\/blog\/wp-json\/wp\/v2\/tags?post=10465"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}