Function generateHash

packages/common/http/src/transfer_cache.ts:571–700

(value: string)

 * preventing cache key collision attacks.
 */
export function generateHash(value: string): string {
  textEncoder ??= new TextEncoder();
  const inputBytes = textEncoder.encode(value);

  // Initial hash values (first 32 bits of the fractional parts of the square roots of the first 8 primes 2..19):
  let hashState0 = 0x6a09e667;
  let hashState1 = 0xbb67ae85;
  let hashState2 = 0x3c6ef372;
  let hashState3 = 0xa54ff53a;
  let hashState4 = 0x510e527f;
  let hashState5 = 0x9b05688c;
  let hashState6 = 0x1f83d9ab;
  let hashState7 = 0x5be0cd19;

  // Pre-processing (Padding):
  const messageLengthInBits = inputBytes.length * 8;

  // The total length of the padded message must be a multiple of 64 bytes (512 bits)
  const paddedLengthInBytes = (((inputBytes.length + 8) >> 6) + 1) << 6;
  const paddedBytes = new Uint8Array(paddedLengthInBytes);
  paddedBytes.set(inputBytes);
  paddedBytes[inputBytes.length] = 0x80; // Append a single '1' bit (0x80 byte)

  const paddedBytesView = new DataView(paddedBytes.buffer);
  const lowBits = messageLengthInBits >>> 0;
  const highBits = (messageLengthInBits / 0x100000000) >>> 0;
  paddedBytesView.setUint32(paddedLengthInBytes - 8, highBits, false);
  paddedBytesView.setUint32(paddedLengthInBytes - 4, lowBits, false);

  // Process the message in successive 64-byte chunks:
  const messageSchedule = new Uint32Array(64);
  for (let chunkOffset = 0; chunkOffset < paddedLengthInBytes; chunkOffset += 64) {
    // Initialize first 16 words of the message schedule:
    for (let i = 0; i < 16; i++) {
      messageSchedule[i] = paddedBytesView.getUint32(chunkOffset + i * 4, false);
    }

    // Extend to 64 words:
    for (let i = 16; i < 64; i++) {
      const prevWord15 = messageSchedule[i - 15];
      const sigma0 =
        (((prevWord15 >>> 7) | (prevWord15 << 25)) ^
          ((prevWord15 >>> 18) | (prevWord15 << 14)) ^
          (prevWord15 >>> 3)) >>>
        0;

      const prevWord2 = messageSchedule[i - 2];
      const sigma1 =
        (((prevWord2 >>> 17) | (prevWord2 << 15)) ^
          ((prevWord2 >>> 19) | (prevWord2 << 13)) ^
          (prevWord2 >>> 10)) >>>
        0;

      messageSchedule[i] =
        (messageSchedule[i - 16] + sigma0 + messageSchedule[i - 7] + sigma1) >>> 0;
    }

    // Initialize working variables to current hash values: