sha1.js

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  SHA-1 implementation in JavaScript | (c) Chris Veness 2002-2010 | www.movable-type.co.uk      */
/*   - see http://csrc.nist.gov/groups/ST/toolkit/secure_hashing.html                             */
/*         http://csrc.nist.gov/groups/ST/toolkit/examples.html                                   */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

var Sha1 = {}; // Sha1 namespace

/**
 * Generates SHA-1 hash of string
 *
 * @param {String} msg                String to be hashed
 * @param {Boolean} [utf8encode=true] Encode msg as UTF-8 before generating hash
 * @returns {String}                  Hash of msg as hex character string
 */
Sha1.hash = function (msg, utf8encode) {
	utf8encode = typeof utf8encode == "undefined" ? true : utf8encode;

	// convert string to UTF-8, as SHA only deals with byte-streams
	if (utf8encode) msg = Utf8.encode(msg);

	// constants [§4.2.1]
	var K = [0x5a827999, 0x6ed9eba1, 0x8f1bbcdc, 0xca62c1d6];

	// PREPROCESSING

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

	// 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;

	// set initial hash value [§5.3.1]
	var H0 = 0x67452301;
	var H1 = 0xefcdab89;
	var H2 = 0x98badcfe;
	var H3 = 0x10325476;
	var H4 = 0xc3d2e1f0;

	// HASH COMPUTATION [§6.1.2]

	var W = new Array(80);
	var a, b, c, d, e;
	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 < 80; t++)
			W[t] = Sha1.ROTL(W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16], 1);

		// 2 - initialise five working variables a, b, c, d, e with previous hash value
		a = H0;
		b = H1;
		c = H2;
		d = H3;
		e = H4;

		// 3 - main loop
		for (var t = 0; t < 80; t++) {
			var s = Math.floor(t / 20); // seq for blocks of 'f' functions and 'K' constants
			var T =
				(Sha1.ROTL(a, 5) + Sha1.f(s, b, c, d) + e + K[s] + W[t]) &
				0xffffffff;
			e = d;
			d = c;
			c = Sha1.ROTL(b, 30);
			b = a;
			a = T;
		}

		// 4 - compute the new intermediate hash value
		H0 = (H0 + a) & 0xffffffff; // note 'addition modulo 2^32'
		H1 = (H1 + b) & 0xffffffff;
		H2 = (H2 + c) & 0xffffffff;
		H3 = (H3 + d) & 0xffffffff;
		H4 = (H4 + e) & 0xffffffff;
	}

	return (
		Sha1.toHexStr(H0) +
		Sha1.toHexStr(H1) +
		Sha1.toHexStr(H2) +
		Sha1.toHexStr(H3) +
		Sha1.toHexStr(H4)
	);
};

//
// function 'f' [§4.1.1]
//
Sha1.f = function (s, x, y, z) {
	switch (s) {
		case 0:
			return (x & y) ^ (~x & z); // Ch()
		case 1:
			return x ^ y ^ z; // Parity()
		case 2:
			return (x & y) ^ (x & z) ^ (y & z); // Maj()
		case 3:
			return x ^ y ^ z; // Parity()
	}
};

//
// rotate left (circular left shift) value x by n positions [§3.2.5]
//
Sha1.ROTL = function (x, n) {
	return (x << n) | (x >>> (32 - n));
};

//
// hexadecimal representation of a number
//   (note toString(16) is implementation-dependant, and
//   in IE returns signed numbers when used on full words)
//
Sha1.toHexStr = function (n) {
	var s = "",
		v;
	for (var i = 7; i >= 0; i--) {
		v = (n >>> (i * 4)) & 0xf;
		s += v.toString(16);
	}
	return s;
};

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  Utf8 class: encode / decode between multi-byte Unicode characters and UTF-8 multiple          */
/*              single-byte character encoding (c) Chris Veness 2002-2010                         */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

var Utf8 = {}; // Utf8 namespace

/**
 * Encode multi-byte Unicode string into utf-8 multiple single-byte characters
 * (BMP / basic multilingual plane only)
 *
 * Chars in range U+0080 - U+07FF are encoded in 2 chars, U+0800 - U+FFFF in 3 chars
 *
 * @param {String} strUni Unicode string to be encoded as UTF-8
 * @returns {String} encoded string
 */
Utf8.encode = function (strUni) {
	// use regular expressions & String.replace callback function for better efficiency
	// than procedural approaches
	var strUtf = strUni.replace(
		/[\u0080-\u07ff]/g, // U+0080 - U+07FF => 2 bytes 110yyyyy, 10zzzzzz
		function (c) {
			var cc = c.charCodeAt(0);
			return String.fromCharCode(0xc0 | (cc >> 6), 0x80 | (cc & 0x3f));
		}
	);
	strUtf = strUtf.replace(
		/[\u0800-\uffff]/g, // U+0800 - U+FFFF => 3 bytes 1110xxxx, 10yyyyyy, 10zzzzzz
		function (c) {
			var cc = c.charCodeAt(0);
			return String.fromCharCode(
				0xe0 | (cc >> 12),
				0x80 | ((cc >> 6) & 0x3f),
				0x80 | (cc & 0x3f)
			);
		}
	);
	return strUtf;
};

/**
 * Decode utf-8 encoded string back into multi-byte Unicode characters
 *
 * @param {String} strUtf UTF-8 string to be decoded back to Unicode
 * @returns {String} decoded string
 */
Utf8.decode = function (strUtf) {
	// note: decode 3-byte chars first as decoded 2-byte strings could appear to be 3-byte char!
	var strUni = strUtf.replace(
		/[\u00e0-\u00ef][\u0080-\u00bf][\u0080-\u00bf]/g, // 3-byte chars
		function (c) {
			// (note parentheses for precence)
			var cc =
				((c.charCodeAt(0) & 0x0f) << 12) |
				((c.charCodeAt(1) & 0x3f) << 6) |
				(c.charCodeAt(2) & 0x3f);
			return String.fromCharCode(cc);
		}
	);
	strUni = strUni.replace(
		/[\u00c0-\u00df][\u0080-\u00bf]/g, // 2-byte chars
		function (c) {
			// (note parentheses for precence)
			var cc = ((c.charCodeAt(0) & 0x1f) << 6) | (c.charCodeAt(1) & 0x3f);
			return String.fromCharCode(cc);
		}
	);
	return strUni;
};

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */