A version of sha256 that won't break with non-UTF8 web pages

qz-sha256.js

/*!
 * @overview  SHA-256 implementation in JavaScript
 * @copyright Copyright (c) Chris Veness 2002-2014
 * @license   Licensed under MIT license
 *            See http://www.movable-type.co.uk/scripts/sha256.html
 * 
 * WARNING: This library been modified from its original to work without UTF8 support
 *          If using with QZ Tray, please consider upgrading to qz-tray.js 2.1 instead. :)
 */

//@formatter:off
"use strict";


// polyfills
if (typeof String.prototype.utf8Encode == 'undefined') {
    String.prototype.utf8Encode = function() { return unescape(encodeURIComponent(this)); };
}
if (typeof String.prototype.utf8Decode == 'undefined') {
    String.prototype.utf8Decode = function() {
        try { return decodeURIComponent(escape(this)); }
        catch(e) { return this; } // invalid UTF-8? return as-is
    };
}

var Sha256 = {};

// Rotates right (circular right shift) value x by n positions
Sha256._rotr = function(n, x) { return (x >>> n) | (x << (32 - n)); },
// logical functions
Sha256._sig0 = function(x) { return Sha256._rotr(2, x) ^ Sha256._rotr(13, x) ^ Sha256._rotr(22, x); },
Sha256._sig1 = function(x) { return Sha256._rotr(6, x) ^ Sha256._rotr(11, x) ^ Sha256._rotr(25, x); },
Sha256._dev0 = function(x) { return Sha256._rotr(7, x) ^ Sha256._rotr(18, x) ^ (x >>> 3); },
Sha256._dev1 = function(x) { return Sha256._rotr(17, x) ^ Sha256._rotr(19, x) ^ (x >>> 10); },
Sha256._ch = function(x, y, z) { return (x & y) ^ (~x & z); },
Sha256._maj = function(x, y, z) { return (x & y) ^ (x & z) ^ (y & z); },
// note can't use toString(16) as it is implementation-dependant, and in IE returns signed numbers when used on full words
Sha256._hexStr = function(n) { var s = "", v; for(var i = 7; i >= 0; i--) { v = (n >>> (i * 4)) & 0xf; s += v.toString(16); } return s; },
//@formatter:on

Sha256.hash = function(msg) {
    // add trailing '1' bit (+ 0's padding) to string [§5.1.1]
    msg = msg.utf8Encode() + String.fromCharCode(0x80);

    // constants [§4.2.2]
    var K = [
        0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
        0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
        0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
        0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
        0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
        0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
        0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
        0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
    ];
    // initial hash value [§5.3.1]
    var H = [ 0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 ];

    // convert string msg into 512-bit/16-integer blocks arrays of ints [§5.2.1]
    var l = msg.length / 4 + 2; // length (in 32-bit integers) of msg + ‘1’ + appended length
    var N = Math.ceil(l / 16);  // number of 16-integer-blocks required to hold 'l' ints
    var M = new Array(N);

    for(var i = 0; i < N; i++) {
        M[i] = new Array(16);
        for(var j = 0; j < 16; j++) {  // encode 4 chars per integer, big-endian encoding
            M[i][j] = (msg.charCodeAt(i * 64 + j * 4) << 24) | (msg.charCodeAt(i * 64 + j * 4 + 1) << 16) |
                (msg.charCodeAt(i * 64 + j * 4 + 2) << 8) | (msg.charCodeAt(i * 64 + j * 4 + 3));
        } // note running off the end of msg is ok 'cos bitwise ops on NaN return 0
    }
    // add length (in bits) into final pair of 32-bit integers (big-endian) [§5.1.1]
    // note: most significant word would be (len-1)*8 >>> 32, but since JS converts
    // bitwise-op args to 32 bits, we need to simulate this by arithmetic operators
    M[N-1][14] = ((msg.length - 1) * 8) / Math.pow(2, 32);
    M[N-1][14] = Math.floor(M[N-1][14]);
    M[N-1][15] = ((msg.length - 1) * 8) & 0xffffffff;

    // HASH COMPUTATION [§6.1.2]
    var W = new Array(64); var a, b, c, d, e, f, g, h;
    for(var i = 0; i < N; i++) {
        // 1 - prepare message schedule 'W'
        for(var t = 0; t < 16; t++) { W[t] = M[i][t]; }
        for(var t = 16; t < 64; t++) { W[t] = (Sha256._dev1(W[t-2]) + W[t-7] + Sha256._dev0(W[t-15]) + W[t-16]) & 0xffffffff; }
        // 2 - initialise working variables a, b, c, d, e, f, g, h with previous hash value
        a = H[0]; b = H[1]; c = H[2]; d = H[3]; e = H[4]; f = H[5]; g = H[6]; h = H[7];
        // 3 - main loop (note 'addition modulo 2^32')
        for(var t = 0; t < 64; t++) {
            var T1 = h + Sha256._sig1(e) + Sha256._ch(e, f, g) + K[t] + W[t];
            var T2 = Sha256._sig0(a) + Sha256._maj(a, b, c);
            h = g; g = f; f = e; e = (d + T1) & 0xffffffff;
            d = c; c = b; b = a; a = (T1 + T2) & 0xffffffff;
        }
        // 4 - compute the new intermediate hash value (note 'addition modulo 2^32')
        H[0] = (H[0]+a) & 0xffffffff; H[1] = (H[1]+b) & 0xffffffff; H[2] = (H[2]+c) & 0xffffffff; H[3] = (H[3]+d) & 0xffffffff;
        H[4] = (H[4]+e) & 0xffffffff; H[5] = (H[5]+f) & 0xffffffff; H[6] = (H[6]+g) & 0xffffffff; H[7] = (H[7]+h) & 0xffffffff;
    }

    return Sha256._hexStr(H[0]) + Sha256._hexStr(H[1]) + Sha256._hexStr(H[2]) + Sha256._hexStr(H[3]) +
        Sha256._hexStr(H[4]) + Sha256._hexStr(H[5]) + Sha256._hexStr(H[6]) + Sha256._hexStr(H[7]);
}