Function normalizeKeyLength

lib/internal/crypto/mac.js:45–64

(handle, algorithm)

const kUsages = ['sign', 'verify'];

function normalizeKeyLength(handle, algorithm) {
  let length = handle.getSymmetricKeySize() * 8;
  if (length === 0 && algorithm.name === 'HMAC')
    throw lazyDOMException('Zero-length key is not supported', 'DataError');

  if (algorithm.length !== undefined) {
    const byteLength = numBitsToBytes(algorithm.length);
    if (byteLength !== handle.getSymmetricKeySize())
      throw lazyDOMException('Invalid key length', 'DataError');

    if (algorithm.length % 8 !== 0) {
      handle = importSecretKey(
        truncateToBitLength(algorithm.length, handle.export()));
    }

    length = algorithm.length;
  }

  return { handle, length };
}

function hmacGenerateKey(algorithm, extractable, usages) {
  const {