{"id":188,"date":"2017-07-17T17:20:54","date_gmt":"2017-07-17T21:20:54","guid":{"rendered":"https:\/\/dwan.org\/?p=188"},"modified":"2019-10-25T15:15:20","modified_gmt":"2019-10-25T19:15:20","slug":"the-oldest-part-of-blockchain","status":"publish","type":"post","link":"https:\/\/dwan.org\/index.php\/2017\/07\/17\/the-oldest-part-of-blockchain\/","title":{"rendered":"The oldest part of Blockchain"},"content":{"rendered":"

Public key encryption<\/a>, or PKE, is one of the oldest techniques in the blockchain toolbox. PKE dates from the 1970s and has a lineage of being \u201cdiscovered\u201d by both military and civilian researchers. It\u2019s powerful stuff: One of the early implementations of a PKE system, called \u201cRSA,\u201d was famously classified as a munition and subject to export control by the United States government<\/a>.<\/p>\n

While PKE (also called \u201casymmetric key\u201d) is a critical technology in Blockchain systems, I care about it mostly because I get a lot of email. With PKE it is conceptually straightforward to encrypt and \u201csign\u201d a message in such a way that the identity of the sender is publicly verifiable and that the intended receiver is the only one who can open it. I\u2019ll explain why that matters for my INBOX further on in this post.<\/p>\n

Most of the algorithms that underpin PKE make use of pairs of numbers \u2013 called \u201ckeys\u201d \u2013 that are related in a particular way. These \u201ckey pairs\u201d are used as input to algorithms to encrypt and decrypt messages. A message that has been encrypted with one of the keys in a pair can only be decrypted using the matching key. As with crytographic hashes, these systems rely on the fact that while it is straightforward to create a pair of keys, it is computationally impractical to guess the second key in a pair given only the first.<\/p>\n

This is conceptually distinct from \u201csymmetric\u201d key algorithms, which use the same key for both encryption and decryption.<\/p>\n

In one common use of PKE, one half of a key pair is designated as \u201cpublic,\u201d while the other is \u201cprivate.\u201d We share the public key widely, posting it on websites and key registries. The private key is closely held. If someone wants to send me a message, they encrypt it using my<\/b> public key. Since I\u2019m the only one with the private partner to that public key, I\u2019m the only one who can decrypt the message.<\/p>\n

Similarly, if the sender wants to \u201csign\u201d their message, they can encrypt a message using their private<\/i> key. In this case, only people with access to the public key will be able to decrypt it. This is, of course, not very limiting. Anybody in the world has access to the public key. However, it is still useful, because we know that this particular message was encrypted using the private partner to that public key.<\/p>\n

What is particularly cool is that we can \u201cstack\u201d these operations, building them one on top of the other. A very common approach is to encrypt a message twice, first using the sender\u2019s private key to provide verification of their identity, and then a second time using the recipient\u2019s public key, to ensure that only the recipient can open the message.<\/p>\n

Many Blockchain systems use this system to verify that the person (or people, or computer program) authorizing a transaction is in fact allowed to do so. In fact, because key pairs are cheap and plentiful, every single Bitcoin transaction has used a unique pair of keys, created just for that one event.<\/p>\n

Back to my surplus of email: None of my banks or healthcare providers have deployed this nearly 40 year old capability for communicating with me. Instead, a growing fraction of my inbound email consists of notifications that I have a message waiting on some \u201csecure message center.\u201d I am exhorted to click a link and sometimes required to enter my password in order to see the message.<\/p>\n

This practice is actively harmful. Fraudulent links in emails are among the primary vectors by which computers are infected with malware. When we teach the absolute basics of information security, \u201cdon\u2019t click the link,\u201d comes right after \u201cdon\u2019t share your password,\u201d but before \u201cwe will never ask for your password.\u201d<\/p>\n

Email systems that use PKE have been around since I\u2019ve been using technology, and somehow my bank and my hospital haven\u2019t caught on. The HIPAA requirement to use \u201csecure messaging,\u201d has driven them backwards, not forwards.<\/p>\n

Perhaps if we call it \u201cBlockchain messaging,\u201d it\u2019ll finally catch on.<\/p>\n","protected":false},"excerpt":{"rendered":"

Public key encryption, or PKE, is one of the oldest techniques in the blockchain toolbox. PKE dates from the 1970s and has a lineage of being \u201cdiscovered\u201d by both military and civilian researchers. It\u2019s powerful stuff: One of the early implementations of a PKE system,…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22,10],"tags":[3,17,16],"class_list":["post-188","post","type-post","status-publish","format-standard","hentry","category-basics","category-blockchain","tag-blockchain","tag-encryption","tag-security"],"_links":{"self":[{"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/posts\/188","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/comments?post=188"}],"version-history":[{"count":4,"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/posts\/188\/revisions"}],"predecessor-version":[{"id":1161,"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/posts\/188\/revisions\/1161"}],"wp:attachment":[{"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/media?parent=188"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/categories?post=188"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dwan.org\/index.php\/wp-json\/wp\/v2\/tags?post=188"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}