148 lines
6.4 KiB
JavaScript
148 lines
6.4 KiB
JavaScript
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*/
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/* Libravatar retrieval for Fedora FAS usernames */
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/* (c) Ralph Bean 2015 / MIT License */
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/* Original SHA-256 implementation in JavaScript */
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/* (c) Chris Veness 2002-2014 / MIT Licence */
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/* */
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/* - see http://csrc.nist.gov/groups/ST/toolkit/secure_hashing.html */
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/* http://csrc.nist.gov/groups/ST/toolkit/examples.html */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*/
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'use strict';
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var sha256 = {};
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var libravatar = {};
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/**
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* Generates SHA-256 hash of string.
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*
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* @param {string} msg - String to be hashed
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* @returns {string} Hash of msg as hex character string
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*/
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sha256.hash = function(msg) {
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// convert string to UTF-8, as SHA only deals with byte-streams
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msg = msg.utf8Encode();
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// constants [§4.2.2]
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var K = [
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0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
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0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
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0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
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0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
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0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
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0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
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0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
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0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2 ];
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// initial hash value [§5.3.1]
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var H = [
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0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 ];
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// PREPROCESSING
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msg += String.fromCharCode(0x80); // add trailing '1' bit (+ 0's padding) to string [§5.1.1]
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// convert string msg into 512-bit/16-integer blocks arrays of ints [§5.2.1]
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var l = msg.length/4 + 2; // length (in 32-bit integers) of msg + ‘1’ + appended length
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var N = Math.ceil(l/16); // number of 16-integer-blocks required to hold 'l' ints
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var M = new Array(N);
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for (var i=0; i<N; i++) {
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M[i] = new Array(16);
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for (var j=0; j<16; j++) { // encode 4 chars per integer, big-endian encoding
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M[i][j] = (msg.charCodeAt(i*64+j*4)<<24) | (msg.charCodeAt(i*64+j*4+1)<<16) |
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(msg.charCodeAt(i*64+j*4+2)<<8) | (msg.charCodeAt(i*64+j*4+3));
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} // note running off the end of msg is ok 'cos bitwise ops on NaN return 0
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}
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// add length (in bits) into final pair of 32-bit integers (big-endian) [§5.1.1]
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// note: most significant word would be (len-1)*8 >>> 32, but since JS converts
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// bitwise-op args to 32 bits, we need to simulate this by arithmetic operators
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M[N-1][14] = ((msg.length-1)*8) / Math.pow(2, 32); M[N-1][14] = Math.floor(M[N-1][14]);
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M[N-1][15] = ((msg.length-1)*8) & 0xffffffff;
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// HASH COMPUTATION [§6.1.2]
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var W = new Array(64); var a, b, c, d, e, f, g, h;
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for (var i=0; i<N; i++) {
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// 1 - prepare message schedule 'W'
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for (var t=0; t<16; t++) W[t] = M[i][t];
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for (var t=16; t<64; t++) W[t] = (sha256.SmallSigma1(W[t-2]) + W[t-7] + sha256.SmallSigma0(W[t-15]) + W[t-16]) & 0xffffffff;
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// 2 - initialise working variables a, b, c, d, e, f, g, h with previous hash value
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a = H[0]; b = H[1]; c = H[2]; d = H[3]; e = H[4]; f = H[5]; g = H[6]; h = H[7];
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// 3 - main loop (note 'addition modulo 2^32')
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for (var t=0; t<64; t++) {
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var T1 = h + sha256.BigSigma1(e) + sha256.Ch(e, f, g) + K[t] + W[t];
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var T2 = sha256.BigSigma0(a) + sha256.Maj(a, b, c);
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h = g;
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g = f;
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f = e;
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e = (d + T1) & 0xffffffff;
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d = c;
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c = b;
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b = a;
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a = (T1 + T2) & 0xffffffff;
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}
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// 4 - compute the new intermediate hash value (note 'addition modulo 2^32')
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H[0] = (H[0]+a) & 0xffffffff;
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H[1] = (H[1]+b) & 0xffffffff;
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H[2] = (H[2]+c) & 0xffffffff;
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H[3] = (H[3]+d) & 0xffffffff;
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H[4] = (H[4]+e) & 0xffffffff;
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H[5] = (H[5]+f) & 0xffffffff;
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H[6] = (H[6]+g) & 0xffffffff;
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H[7] = (H[7]+h) & 0xffffffff;
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}
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return sha256.toHexStr(H[0]) + sha256.toHexStr(H[1]) + sha256.toHexStr(H[2]) + sha256.toHexStr(H[3]) +
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sha256.toHexStr(H[4]) + sha256.toHexStr(H[5]) + sha256.toHexStr(H[6]) + sha256.toHexStr(H[7]);
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};
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sha256.ROTR = function(n, x) {
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return (x >>> n) | (x << (32-n));
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};
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sha256.BigSigma0 = function(x) { return sha256.ROTR(2, x) ^ sha256.ROTR(13, x) ^ sha256.ROTR(22, x); };
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sha256.BigSigma1 = function(x) { return sha256.ROTR(6, x) ^ sha256.ROTR(11, x) ^ sha256.ROTR(25, x); };
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sha256.SmallSigma0 = function(x) { return sha256.ROTR(7, x) ^ sha256.ROTR(18, x) ^ (x>>>3); };
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sha256.SmallSigma1 = function(x) { return sha256.ROTR(17, x) ^ sha256.ROTR(19, x) ^ (x>>>10); };
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sha256.Ch = function(x, y, z) { return (x & y) ^ (~x & z); };
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sha256.Maj = function(x, y, z) { return (x & y) ^ (x & z) ^ (y & z); };
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sha256.toHexStr = function(n) {
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// note can't use toString(16) as it is implementation-dependant,
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// and in IE returns signed numbers when used on full words
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var s="", v;
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for (var i=7; i>=0; i--) { v = (n>>>(i*4)) & 0xf; s += v.toString(16); }
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return s;
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};
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if (typeof String.prototype.utf8Encode == 'undefined') {
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String.prototype.utf8Encode = function() {
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return unescape( encodeURIComponent( this ) );
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};
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}
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if (typeof String.prototype.utf8Decode == 'undefined') {
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String.prototype.utf8Decode = function() {
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try {
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return decodeURIComponent( escape( this ) );
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} catch (e) {
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return this; // invalid UTF-8? return as-is
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}
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};
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}
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/* This is all that we need the sha256 code for... */
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libravatar.url = function(username, s, d) {
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if (s === undefined) s = 64;
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if (d === undefined) d = 'retro';
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var openid = 'http://' + username + '.id.fedoraproject.org/'
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var hash = sha256.hash(openid);
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return 'https://seccdn.libravatar.org/avatar/' + hash + '?s=' + s + '&d=' + d;
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}
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