sha1.d.ts

export function sha1(str: string | ArrayBuffer, opts?: Object): string;

sha1.js

/*! https://gist.github.com/allex/2c83d6dfa08f47d23cdda4351d1cc406 */

/**
 * 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
 */

/**
 * Generates SHA-1 hash of string or buffer.
 *
 * @param   {string|arraybuffer} msg - (Unicode) data to be hashed.
 * @param   {Object} [options]
 * @param   {string} [options.format=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.digest=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.
 */
const sha1 = (msg, options) => {
  options = options || {}
  if (!options.format && typeof msg === 'object' && msg.byteLength) {
    options.format = 'buffer'
  }

  const defaults = { format: 'string', digest: 'hex' };
  const opt = Object.assign(defaults, options);

  switch (opt.format) {
    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
    case 'buffer': break;
  }

  // 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] = 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 = (ROTL(a,5) + f(s,b,c,d) + e + K[s] + W[t]) >>> 0;
      e = d;
      d = c;
      c = 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.digest == 'hex-w' ? ' ' : '';

  return H.join(separator);

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

  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
 */
const 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
 */
const ROTL = (x, n) => {
  return (x<<n) | (x>>>(32-n));
}

exports.sha1 = sha1

https://gist.github.com/dysinger/369944/b6246ddf995c892ca3616da21c0eabf58e6f24f7
https://www.movable-type.co.uk/scripts/sha1.html