Function continueScramConversation

src/cmap/auth/scram.ts:116–204

(
  cryptoMethod: CryptoMethod,
  response: Document,
  authContext: AuthContext
)

}

async function continueScramConversation(
  cryptoMethod: CryptoMethod,
  response: Document,
  authContext: AuthContext
): Promise<void> {
  const connection = authContext.connection;
  const credentials = authContext.credentials;
  if (!credentials) {
    throw new MongoMissingCredentialsError('AuthContext must provide credentials.');
  }
  if (!authContext.nonce) {
    throw new MongoInvalidArgumentError('Unable to continue SCRAM without valid nonce');
  }
  const nonce = authContext.nonce;

  const db = credentials.source;
  const username = cleanUsername(credentials.username);
  const password = credentials.password;

  const processedPassword =
    cryptoMethod === 'sha256' ? saslprep(password) : passwordDigest(username, password);

  const payload: Binary = ByteUtils.isUint8Array(response.payload)
    ? new Binary(response.payload)
    : response.payload;

  const dict = parsePayload(payload);

  const iterations = parseInt(dict.i, 10);
  if (iterations && iterations < 4096) {
    // TODO(NODE-3483)
    throw new MongoRuntimeError(`Server returned an invalid iteration count ${iterations}`);
  }

  const salt = dict.s;
  const rnonce = dict.r;
  if (rnonce.startsWith('nonce')) {
    // TODO(NODE-3483)
    throw new MongoRuntimeError(`Server returned an invalid nonce: ${rnonce}`);
  }

  // Set up start of proof
  const withoutProof = `c=biws,r=${rnonce}`;
  const saltedPassword = await HI(
    processedPassword,
    ByteUtils.fromBase64(salt),
    iterations,
    cryptoMethod
  );

  const clientKey = await HMAC(cryptoMethod, saltedPassword, 'Client Key');
  const serverKey = await HMAC(cryptoMethod, saltedPassword, 'Server Key');
  const storedKey = await H(cryptoMethod, clientKey);
  const firstMessageBytes = clientFirstMessageBare(username, nonce);
  const firstMessage = ByteUtils.toUTF8(firstMessageBytes, 0, firstMessageBytes.length, false);
  const payloadString = ByteUtils.toUTF8(payload.buffer, 0, payload.position, false);
  const authMessage = [firstMessage, payloadString, withoutProof].join(',');