{"id":1391,"date":"2020-02-29T19:09:21","date_gmt":"2020-02-29T11:09:21","guid":{"rendered":"http:\/\/149.129.74.185\/?p=1391"},"modified":"2020-02-29T19:09:21","modified_gmt":"2020-02-29T11:09:21","slug":"%e7%bd%91%e7%bb%9c%e5%ae%89%e5%85%a8-week-1-note-3","status":"publish","type":"post","link":"http:\/\/www.magicmipamipa.com\/?p=1391","title":{"rendered":"[\u7f51\u7edc\u5b89\u5168] Week 1 Note 3"},"content":{"rendered":"<h2 id=\"mcetoc_1e282h0000\">Cryptography<\/h2>\n<p>Why\uff1f<\/p>\n<p style=\"padding-left: 30px;\">prevent third parties from reading private messages<\/p>\n<p>How\uff1f<\/p>\n<p style=\"padding-left: 30px;\">encrypt messages before transmission;<\/p>\n<p style=\"padding-left: 30px;\">decrypt messages upon receipt;<\/p>\n<p>what:<\/p>\n<p style=\"padding-left: 30px;\">confidentiality\uff08\u4fdd\u5bc6\uff09 &#8212; <span style=\"background-color: #ffff00;\">secrecy<\/span><\/p>\n<p style=\"padding-left: 30px;\">integrity\uff08\u5b8c\u6574\uff09 &#8212; <span style=\"background-color: #ffff00;\">accuracy<\/span><\/p>\n<p style=\"padding-left: 30px;\">authentication\uff08\u8eab\u4efd\u9a8c\u8bc1\uff09 &#8212; <span style=\"background-color: #ffff00;\">ascription\uff08\u5f52\u5c5e\uff09<\/span><\/p>\n<p style=\"padding-left: 30px;\">non-repudiation\uff08\u4e0d\u53ef\u62b5\u8d56\uff09 &#8212; <span style=\"background-color: #ffff00;\">liability<\/span><\/p>\n<p>which\uff1a<\/p>\n<p>&nbsp;<\/p>\n<h3 id=\"mcetoc_1e284fqb61\">Transiposition<\/h3>\n<p>Scramble input to produce output<\/p>\n<p>Key: the permutation of input\u00a0<span style=\"background-color: #ffff00;\">permutation\uff1a\u6392\u5217\u7ec4\u5408<\/span><\/p>\n<p>&nbsp;<\/p>\n<h3 id=\"mcetoc_1e284l9pj2\">Substitution<\/h3>\n<p>Substitute one input for another<\/p>\n<p>Key: the substitution( cookbook )<\/p>\n<p>\uff08\uff01\uff09\u7834\u89e3\u4e00\u4e2a\u5bc6\u7801\u5c31\u53ef\u4ee5\u89e3\u5bc6\u6240\u6709\u7684\u901a\u8bdd\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3 id=\"mcetoc_1e284phhq3\">OTP: One-Time Pad<\/h3>\n<p>Key: a secret bit string <span style=\"color: #ff9900;\">s<\/span> of length <span style=\"color: #ff9900;\">n<\/span><\/p>\n<p>messgae <span style=\"color: #ff9900;\">m<\/span> of length n , the ciphertext <span style=\"color: #ff9900;\">c<\/span> as:<\/p>\n<p>for all <span style=\"color: #ff9900;\">i<\/span> = 1 to n:\u00a0<span style=\"color: #ff9900; background-color: #ffff00;\">\u00a0ci = mi\u2295si\u00a0<\/span><\/p>\n<p>&nbsp;<\/p>\n<h3 id=\"mcetoc_1e2851c124\">DES: Data Encrytion Standard<\/h3>\n<ul>\n<li>Block cipher<\/li>\n<li>64-bit plaintext\/ciphertext<\/li>\n<li>56-bit key<\/li>\n<\/ul>\n<h3 id=\"mcetoc_1e289qh4r5\">3DES\/TDES: Triple DES<\/h3>\n<h3 id=\"mcetoc_1e289qsko6\">AES: Advanced Encryption Standard<\/h3>\n<p>KeyExpansion: Rijndael\u2019s key schedule derive a 128-bit key for each round<\/p>\n<p>Initial round key addition AddRoundKey: state XOR round key<\/p>\n<p>9 rounds (assume 10 rounds needed) SubBytes, ShiftRows, MixColumns, AddRoundKey<\/p>\n<p>Final round without MixColumns<\/p>\n<h3 id=\"mcetoc_1e289s71n7\">RSA<\/h3>\n<h3 id=\"mcetoc_1e289s71n8\">Homomorphic Cryptography<\/h3>\n<h3 id=\"mcetoc_1e289s71n9\">Proxy Re-encryption<\/h3>\n<h3 id=\"mcetoc_1e289t1h0a\">Forward Secrecy<\/h3>\n<ul>\n<li>Session keys will not be compromised even if the private key of the server is compromised<\/li>\n<li>By generating a unique session key for every session a user initiates, the compromise of a single session key will not affect any data other than that exchanged in the specific session protected by that particular key<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Cryptography Why\uff1f prevent third parties from readi [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[16,39],"tags":[],"_links":{"self":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts\/1391"}],"collection":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1391"}],"version-history":[{"count":1,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts\/1391\/revisions"}],"predecessor-version":[{"id":1392,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts\/1391\/revisions\/1392"}],"wp:attachment":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1391"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1391"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1391"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}