121 lines
4.8 KiB
JavaScript
121 lines
4.8 KiB
JavaScript
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* SHA-1 (FIPS 180-4) implementation in JavaScript (c) Chris Veness 2002-2016 */
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/* MIT Licence */
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/* www.movable-type.co.uk/scripts/sha1.html */
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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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function f(s, x, y, z) {
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switch (s) {
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case 0: return (x & y) ^ (~x & z); // Ch()
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case 1: return x ^ y ^ z; // Parity()
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case 2: return (x & y) ^ (x & z) ^ (y & z); // Maj()
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case 3: return x ^ y ^ z; // Parity()
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}
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}
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function ROTL(x, n) {
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return (x<<n) | (x>>>(32-n));
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}
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var Sha1 = {};
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Sha1.hash = function(msg, options) {
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var defaults = { msgFormat: 'string', outFormat: 'hex' };
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var opt = Object.assign(defaults, options);
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switch (opt.msgFormat) {
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default: // default is to convert string to UTF-8, as SHA only deals with byte-streams
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case 'string': msg = Sha1.utf8Encode(msg); break;
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case 'hex-bytes':msg = Sha1.hexBytesToString(msg); break; // mostly for running tests
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}
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// constants [¤4.2.1]
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var K = [ 0x5a827999, 0x6ed9eba1, 0x8f1bbcdc, 0xca62c1d6 ];
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// initial hash value [¤5.3.1]
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var H = [ 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, 0xc3d2e1f0 ];
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// PREPROCESSING [¤6.1.1]
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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 + Ô1Õ + 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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for (var i=0; i<N; i++) {
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var W = new Array(80);
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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<80; t++) W[t] = ROTL(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16], 1);
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// 2 - initialise five working variables a, b, c, d, e with previous hash value
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var a = H[0], b = H[1], c = H[2], d = H[3], e = H[4];
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// 3 - main loop (use JavaScript '>>> 0' to emulate UInt32 variables)
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for (var t=0; t<80; t++) {
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var s = Math.floor(t/20); // seq for blocks of 'f' functions and 'K' constants
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var T = (ROTL(a,5) + f(s,b,c,d) + e + K[s] + W[t]) >>> 0;
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e = d;
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d = c;
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c = ROTL(b, 30) >>> 0;
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b = a;
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a = T;
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}
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// 4 - compute the new intermediate hash value (note 'addition modulo 2^32' Ð JavaScript
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// '>>> 0' coerces to unsigned UInt32 which achieves modulo 2^32 addition)
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H[0] = (H[0]+a) >>> 0;
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H[1] = (H[1]+b) >>> 0;
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H[2] = (H[2]+c) >>> 0;
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H[3] = (H[3]+d) >>> 0;
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H[4] = (H[4]+e) >>> 0;
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}
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// convert H0..H4 to hex strings (with leading zeros)
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for (var h=0; h<H.length; h++) H[h] = ('00000000'+H[h].toString(16)).slice(-8);
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// concatenate H0..H4, with separator if required
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var separator = opt.outFormat=='hex-w' ? ' ' : '';
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return H.join(separator);
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};
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Sha1.utf8Encode = function(str) {
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return unescape(encodeURIComponent(str));
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};
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Sha1.hexBytesToString = function(hexStr) {
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hexStr = hexStr.replace(' ', ''); // allow space-separated groups
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var str = '';
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for (var i=0; i<hexStr.length; i+=2) {
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str += String.fromCharCode(parseInt(hexStr.slice(i, i+2), 16));
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}
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return str;
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};
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module.exports = Sha1; // CommonJs export
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