{"id":360,"date":"2019-07-29T21:45:07","date_gmt":"2019-07-29T21:45:07","guid":{"rendered":"https:\/\/www.rapidsslonline.com\/ssl\/?p=360"},"modified":"2019-09-06T07:03:41","modified_gmt":"2019-09-06T07:03:41","slug":"difference-between-public-and-private-key","status":"publish","type":"post","link":"https:\/\/www.rapidsslonline.com\/ssl\/difference-between-public-and-private-key\/","title":{"rendered":"The Difference Between Public Key and Private Key Explained"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">What is the difference between private key vs public key encryption? It may not be what you think<\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u201cSSL Public Keys and SSL Private Keys are like ebony and ivory, living together in perfect harmony. Side-by-side on the piano keyboard, oh Lord, why don\u2019t we.\u201d \u2014 Paul McCartney and Stevie Wonder, when they addressed the difference between public and private keys in cryptography.<\/p><\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">The above quote about public keys and private keys is fake, obviously. But we know if got your attention. Now, without further ado, we&#8217;ll explain the difference between public key and private key encryption.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Public Key vs Private Key Cryptography<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">In SSL, and in public key infrastructure (PKI) in general,\nkeys are used to perform a range of cryptographic functions. When a client\narrives at a website, the two use their public and private keys during a\nprocess called the SSL handshake. That handshake creates a third key, what\u2019s\nknown as a session key, to communicate during the connection.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A session key is symmetric, meaning it\u2019s capable of both encrypting and decrypting. They tend to be smaller, but perform better and still offer ample security. When you communicate online, you\u2019re using one of those symmetric session keys. <strong>You don\u2019t use the public and private keys to communicate.<\/strong> Anyone that tells you that is a Charlatan and you should smite them where they stand. <\/p>\n\n\n\n<h2 class=\"wp-block-heading\">The Roles of Public Keys vs Private Keys in Encryption <\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">So, what do the <a href=\"https:\/\/www.rapidsslonline.com\/blog\/public-key-private-key-encryption\/\">public and private key<\/a> do? Well, probably not what you think. <strong>Public\/private key pairs are <a href=\"https:\/\/www.rapidsslonline.com\/blog\/fundamental-differences-between-symmetric-and-asymmetric-encryption\/\">asymmetric<\/a> \u2014 the public key can encrypt, and the private key can decrypt.<\/strong> Historically, when the RSA cryptosystem is in use, the public\/private key pair handles the transmission of the session key. After all, how else would you exchange and encryption key securely?<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter\"><img decoding=\"async\" width=\"616\" height=\"301\" data-src=\"https:\/\/www.rapidsslonline.com\/ssl\/wp-content\/uploads\/2019\/07\/PublicPrivateKeyEncryption.png\" alt=\"Graphic: difference between public and private key -- this is an illustration of asymmetric encryption.\" class=\"wp-image-361 lazyload\" data-srcset=\"https:\/\/www.rapidsslonline.com\/ssl\/wp-content\/uploads\/2019\/07\/PublicPrivateKeyEncryption.png 616w, https:\/\/www.rapidsslonline.com\/ssl\/wp-content\/uploads\/2019\/07\/PublicPrivateKeyEncryption-300x147.png 300w\" data-sizes=\"(max-width: 616px) 100vw, 616px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 616px; --smush-placeholder-aspect-ratio: 616\/301;\" \/><\/figure><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">With RSA key exchange, the pre-master secret that will be\nused to derive the session key is encrypted with the public key, sent to the\nserver and decrypted with the private key.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">How These Roles Have Changed in TLS 1.3<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">In <a href=\"https:\/\/www.ietf.org\/blog\/tls13\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\" (opens in a new tab)\">TLS 1.3<\/a>, RSA key exchange was banned. So\u2026 this means there\u2019s no longer <a href=\"https:\/\/www.rapidsslonline.com\/blog\/fundamental-differences-between-symmetric-and-asymmetric-encryption\/\">asymmetric encryption<\/a> in the handshake.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Let\u2019s take a moment because that bears repeating: THERE IS NO LONGER ASYMMETRIC ENCRYPTION OCCURRING DURING THE HANDSHAKE SINCE TLS 1.3 KICKED IN.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">So, what do the public\/private key pair do now? <strong>Digital signature authentication<\/strong>. Owing to the nature of the two keys, the public key can be used to verify signatures left by the private key. When a client is presented with a certificate, it uses the corresponding public key to trace the signatures back up the certificate chain and to its root store. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This is now the only use case for the public\/private key pair as of TLS 1.3. <\/p>\n\n\n\n<div class=\"graysection\"><h2>Save Up to 82% on DV SSL Certificates<\/h2>\n<p>Protect a website in a few minutes with a Domain Validated SSL Certificate (DV SSL).<\/p>\n<p><a class=\"more-link floatnone\" style=\"text-decoration: none;\" href=\"https:\/\/www.rapidsslonline.com\/ssl-types\/domain-validation-ssl-certificates.aspx\">Get a DV SSL certificate, starting at $12.42\/year<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>What is the difference between private key vs public key encryption? It may not be what you think \u201cSSL Public Keys and SSL Private Keys are like ebony and ivory,<\/p>\n<div class=\"article-wpr-button\"><a href=\"https:\/\/www.rapidsslonline.com\/ssl\/difference-between-public-and-private-key\/\" class=\"btn btn-green\">Read More<\/a><\/p>\n<div>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13],"tags":[29,27,28,12],"class_list":["post-360","post","type-post","status-publish","format-standard","category-ssl-advanced","tag-encryption","tag-private-key","tag-public-key","tag-tls"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>The Difference Between Public Key and Private Key Explained<\/title>\n<meta name=\"description\" content=\"What is the difference between public and private key in cryptography and encryption, and how 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encryption, and how are the pair used together in the encryption process?","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.rapidsslonline.com\/ssl\/difference-between-public-and-private-key\/","og_locale":"en_US","og_type":"article","og_title":"The Difference Between Public Key and Private Key Explained","og_description":"What is the difference between public and private key in cryptography and encryption, and how are the pair used together in the encryption process?","og_url":"https:\/\/www.rapidsslonline.com\/ssl\/difference-between-public-and-private-key\/","og_site_name":"SSL\/TLS 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