/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* SHA-1 (FIPS 180-4) implementation in JavaScript (c) Chris Veness 2002-2019 */
/* MIT Licence */
/* www.movable-type.co.uk/scripts/sha1.html */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/**
* SHA-1 hash function reference implementation.
*
* This is an annotated direct implementation of FIPS 180-4, without any optimisations. It is
* intended to aid understanding of the algorithm rather than for production use.
*
* While it could be used where performance is not critical, I would recommend using the ‘Web
* Cryptography API’ (developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/digest) for the browser,
* or the ‘crypto’ library (nodejs.org/api/crypto.html#crypto_class_hash) in Node.js.
*
* See csrc.nist.gov/groups/ST/toolkit/secure_hashing.html
* csrc.nist.gov/groups/ST/toolkit/examples.html
*/
class Sha1 {
/**
* Generates SHA-1 hash of string.
*
* @param {string} msg - (Unicode) string to be hashed.
* @param {Object} [options]
* @param {string} [options.msgFormat=string] - Message format: 'string' for JavaScript string
* (gets converted to UTF-8 for hashing); 'hex-bytes' for string of hex bytes ('616263' ≡ 'abc') .
* @param {string} [options.outFormat=hex] - Output format: 'hex' for string of contiguous
* hex bytes; 'hex-w' for grouping hex bytes into groups of (4 byte / 8 character) words.
* @returns {string} Hash of msg as hex character string.
*
* @example
* import Sha1 from './sha1.js';
* const hash = Sha1.hash('abc'); // 'a9993e364706816aba3e25717850c26c9cd0d89d'
*/
static hash(msg, options) {
const defaults = { msgFormat: 'string', outFormat: 'hex' };
const opt = Object.assign(defaults, options);
switch (opt.msgFormat) {
default: // default is to convert string to UTF-8, as SHA only deals with byte-streams
case 'string': msg = utf8Encode(msg); break;
case 'hex-bytes':msg = hexBytesToString(msg); break; // mostly for running tests
}
// constants [§4.2.1]
const K = [ 0x5a827999, 0x6ed9eba1, 0x8f1bbcdc, 0xca62c1d6 ];
// initial hash value [§5.3.1]
const H = [ 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, 0xc3d2e1f0 ];
// PREPROCESSING [§6.1.1]
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]
const l = msg.length/4 + 2; // length (in 32-bit integers) of msg + ‘1’ + appended length
const N = Math.ceil(l/16); // number of 16-integer-blocks required to hold 'l' ints
const M = new Array(N);
for (let i=0; i<N; i++) {
M[i] = new Array(16);
for (let j=0; j<16; j++) { // encode 4 chars per integer, big-endian encoding
M[i][j] = (msg.charCodeAt(i*64+j*4+0)<<24) | (msg.charCodeAt(i*64+j*4+1)<<16)
| (msg.charCodeAt(i*64+j*4+2)<< 8) | (msg.charCodeAt(i*64+j*4+3)<< 0);
} // 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]
for (let i=0; i<N; i++) {
const W = new Array(80);
// 1 - prepare message schedule 'W'
for (let t=0; t<16; t++) W[t] = M[i][t];
for (let 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
let a = H[0], b = H[1], c = H[2], d = H[3], e = H[4];
// 3 - main loop (use JavaScript '>>> 0' to emulate UInt32 variables)
for (let t=0; t<80; t++) {
const s = Math.floor(t/20); // seq for blocks of 'f' functions and 'K' constants
const T = (Sha1.ROTL(a, 5) + Sha1.f(s, b, c, d) + e + K[s] + W[t]) >>> 0;
e = d;
d = c;
c = Sha1.ROTL(b, 30) >>> 0;
b = a;
a = T;
}
// 4 - compute the new intermediate hash value (note 'addition modulo 2^32' – JavaScript
// '>>> 0' coerces to unsigned UInt32 which achieves modulo 2^32 addition)
H[0] = (H[0]+a) >>> 0;
H[1] = (H[1]+b) >>> 0;
H[2] = (H[2]+c) >>> 0;
H[3] = (H[3]+d) >>> 0;
H[4] = (H[4]+e) >>> 0;
}
// convert H0..H4 to hex strings (with leading zeros)
for (let h=0; h<H.length; h++) H[h] = ('00000000'+H[h].toString(16)).slice(-8);
// concatenate H0..H4, with separator if required
const separator = opt.outFormat=='hex-w' ? ' ' : '';
return H.join(separator);
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function utf8Encode(str) {
try {
return new TextEncoder().encode(str, 'utf-8').reduce((prev, curr) => prev + String.fromCharCode(curr), '');
} catch (e) { // no TextEncoder available?
return unescape(encodeURIComponent(str)); // monsur.hossa.in/2012/07/20/utf-8-in-javascript.html
}
}
function hexBytesToString(hexStr) { // convert string of hex numbers to a string of chars (eg '616263' -> 'abc').
const str = hexStr.replace(' ', ''); // allow space-separated groups
return str=='' ? '' : str.match(/.{2}/g).map(byte => String.fromCharCode(parseInt(byte, 16))).join('');
}
}
/**
* Function 'f' [§4.1.1].
* @private
*/
static f(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()
}
}
/**
* Rotates left (circular left shift) value x by n positions [§3.2.5].
* @private
*/
static ROTL(x, n) {
return (x<<n) | (x>>>(32-n));
}
}
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// export default Sha1;