ssm-session/dist/esm-browser/sha256.js

Javascript library for starting an AWS SSM session compatible with Browser and NodeJS

/*
https://github.com/geraintluff/sha256
*/
var sha256 = function sha256(ascii) {
  function rightRotate(value, amount) {
    return value >>> amount | value << 32 - amount;
  }

  var mathPow = Math.pow;
  var maxWord = mathPow(2, 32);
  var lengthProperty = "length";
  var i, j; // Used as a counter across the whole file

  var result = "";
  var words = [];
  var asciiBitLength = ascii[lengthProperty] * 8; //* caching results is optional - remove/add slash from front of this line to toggle
  // Initial hash value: first 32 bits of the fractional parts of the square roots of the first 8 primes
  // (we actually calculate the first 64, but extra values are just ignored)

  var hash = sha256.h = sha256.h || []; // Round constants: first 32 bits of the fractional parts of the cube roots of the first 64 primes

  var k = sha256.k = sha256.k || [];
  var primeCounter = k[lengthProperty];
  /*/
  var hash = [], k = [];
  var primeCounter = 0;
  //*/

  var isComposite = {};

  for (var candidate = 2; primeCounter < 64; candidate++) {
    if (!isComposite[candidate]) {
      for (i = 0; i < 313; i += candidate) {
        isComposite[i] = candidate;
      }

      hash[primeCounter] = mathPow(candidate, 0.5) * maxWord | 0;
      k[primeCounter++] = mathPow(candidate, 1 / 3) * maxWord | 0;
    }
  }

  ascii += "\x80"; // Append '1' bit (plus zero padding)

  while (ascii[lengthProperty] % 64 - 56) {
    ascii += "\x00";
  } // More zero padding


  for (i = 0; i < ascii[lengthProperty]; i++) {
    j = ascii.charCodeAt(i);
    if (j >> 8) return; // ASCII check: only accept characters in range 0-255

    words[i >> 2] |= j << (3 - i) % 4 * 8;
  }

  words[words[lengthProperty]] = asciiBitLength / maxWord | 0;
  words[words[lengthProperty]] = asciiBitLength; // process each chunk

  for (j = 0; j < words[lengthProperty];) {
    var w = words.slice(j, j += 16); // The message is expanded into 64 words as part of the iteration

    var oldHash = hash; // This is now the "working hash", often labelled as variables a...g
    // (we have to truncate as well, otherwise extra entries at the end accumulate

    hash = hash.slice(0, 8);

    for (i = 0; i < 64; i++) {
      //var i2 = i + j;
      // Expand the message into 64 words
      // Used below if
      var w15 = w[i - 15],
          w2 = w[i - 2]; // Iterate

      var a = hash[0],
          e = hash[4];
      var temp1 = hash[7] + (rightRotate(e, 6) ^ rightRotate(e, 11) ^ rightRotate(e, 25)) + ( // S1
      e & hash[5] ^ ~e & hash[6]) + // ch
      k[i] + ( // Expand the message schedule if needed
      w[i] = i < 16 ? w[i] : w[i - 16] + (rightRotate(w15, 7) ^ rightRotate(w15, 18) ^ w15 >>> 3) + // s0
      w[i - 7] + (rightRotate(w2, 17) ^ rightRotate(w2, 19) ^ w2 >>> 10) | // s1
      0); // This is only used once, so *could* be moved below, but it only saves 4 bytes and makes things unreadble

      var temp2 = (rightRotate(a, 2) ^ rightRotate(a, 13) ^ rightRotate(a, 22)) + ( // S0
      a & hash[1] ^ a & hash[2] ^ hash[1] & hash[2]); // maj

      hash = [temp1 + temp2 | 0].concat(hash); // We don't bother trimming off the extra ones, they're harmless as long as we're truncating when we do the slice()

      hash[4] = hash[4] + temp1 | 0;
    }

    for (i = 0; i < 8; i++) {
      hash[i] = hash[i] + oldHash[i] | 0;
    }
  }

  for (i = 0; i < 8; i++) {
    for (j = 3; j + 1; j--) {
      var b = hash[i] >> j * 8 & 255;
      result += (b < 16 ? 0 : "") + b.toString(16);
    }
  }

  return result;
};

export default sha256;