Function normalizeAlgorithm

lib/internal/crypto/util.js:606–676

(algorithm, op)

// adapted for Node.js from Deno's implementation
// https://github.com/denoland/deno/blob/v1.29.1/ext/crypto/00_crypto.js#L195
function normalizeAlgorithm(algorithm, op) {
  if (typeof algorithm === 'string')
    return normalizeAlgorithm({ name: algorithm }, op);

  webidl ??= require('internal/crypto/webidl');

  // 1.
  const registeredAlgorithms = kSupportedAlgorithms[op];
  // 2. 3.
  const initialAlg = webidl.converters.Algorithm(algorithm,
                                                 kNormalizeAlgorithmOpts);
  // 4.
  let algName = initialAlg.name;

  // 5. Case-insensitive lookup via pre-built Map (O(1) instead of O(n)).
  const canonicalName = kAlgorithmNameMap[op]?.get(
    StringPrototypeToUpperCase(algName));
  if (canonicalName === undefined)
    throw lazyDOMException('Unrecognized algorithm name', 'NotSupportedError');

  algName = canonicalName;
  const desiredType = registeredAlgorithms[algName];

  // Fast path everything below if the registered dictionary is null
  if (desiredType === null)
    return { name: algName };

  // 6.
  const normalizedAlgorithm = webidl.converters[desiredType](
    { __proto__: algorithm, name: algName },
    kNormalizeAlgorithmOpts,
  );
  // 7.
  normalizedAlgorithm.name = algName;

  // 9. 10. Pre-computed keys and types from simpleAlgorithmDictionaries.
  const dictMeta = simpleAlgorithmDictionaries[desiredType];
  if (dictMeta) {
    const { keys: dictKeys, types: dictTypes } = dictMeta;
    for (let i = 0; i < dictKeys.length; i++) {
      const member = dictKeys[i];
      const idlType = dictTypes[member];
      const idlValue = normalizedAlgorithm[member];
      // 3.
      if (idlType === 'BufferSource' && idlValue) {
        const isView = ArrayBufferIsView(idlValue);
        const idlValueBytes = isView ?
          new Uint8Array(
            getDataViewOrTypedArrayBuffer(idlValue),
            getDataViewOrTypedArrayByteOffset(idlValue),
            getDataViewOrTypedArrayByteLength(idlValue),
          ) :
          new Uint8Array(
            idlValue,
            0,
            ArrayBufferPrototypeGetByteLength(idlValue),
          );
        normalizedAlgorithm[member] = TypedArrayPrototypeSlice(