crypto.js

// Note: In 0.8 and before, crypto functions all defaulted to using
// binary-encoded strings rather than buffers.

'use strict';

const internalUtil = require('internal/util');
internalUtil.assertCrypto();

exports.DEFAULT_ENCODING = 'buffer';

const constants = process.binding('constants').crypto;
const binding = process.binding('crypto');
const randomBytes = binding.randomBytes;
const getCiphers = binding.getCiphers;
const getHashes = binding.getHashes;
const getCurves = binding.getCurves;
const getFipsCrypto = binding.getFipsCrypto;
const setFipsCrypto = binding.setFipsCrypto;
const timingSafeEqual = binding.timingSafeEqual;

const Buffer = require('buffer').Buffer;
const kBufferMaxLength = require('buffer').kMaxLength;
const stream = require('stream');
const util = require('util');
const LazyTransform = require('internal/streams/lazy_transform');

const DH_GENERATOR = 2;

const ReflectApply = Reflect.apply;

const TypedArrayPrototype = Object.getPrototypeOf(Uint8Array.prototype);
const TypedArrayProto_toStringTag =
    uncurryThis(
      Object.getOwnPropertyDescriptor(TypedArrayPrototype,
                                      Symbol.toStringTag).get);

// This function is borrowed from the function with the same name on V8 Extras'
// `utils` object. V8 implements Reflect.apply very efficiently in conjunction
// with the spread syntax, such that no additional special case is needed for
// function calls w/o arguments.
// Refs: https://github.com/v8/v8/blob/d6ead37d265d7215cf9c5f768f279e21bd170212/src/js/prologue.js#L152-L156
function uncurryThis(func) {
  return (thisArg, ...args) => ReflectApply(func, thisArg, args);
}

function isUint8Array(value) {
  return TypedArrayProto_toStringTag(value) === 'Uint8Array';
}

Object.defineProperty(exports, 'constants', {
  configurable: false,
  enumerable: true,
  value: constants
});

// This is here because many functions accepted binary strings without
// any explicit encoding in older versions of node, and we don't want
// to break them unnecessarily.
function toBuf(str, encoding) {
  if (typeof str === 'string') {
    if (encoding === 'buffer' || !encoding)
      encoding = 'utf8';
    return Buffer.from(str, encoding);
  }
  return str;
}
exports._toBuf = toBuf;

const assert = require('assert');
const StringDecoder = require('string_decoder').StringDecoder;


exports.createHash = exports.Hash = Hash;
function Hash(algorithm, options) {
  if (!(this instanceof Hash))
    return new Hash(algorithm, options);
  this._handle = new binding.Hash(algorithm);
  LazyTransform.call(this, options);
}

util.inherits(Hash, LazyTransform);

Hash.prototype._transform = function _transform(chunk, encoding, callback) {
  this._handle.update(chunk, encoding);
  callback();
};

Hash.prototype._flush = function _flush(callback) {
  this.push(this._handle.digest());
  callback();
};

Hash.prototype.update = function update(data, encoding) {
  encoding = encoding || exports.DEFAULT_ENCODING;
  this._handle.update(data, encoding);
  return this;
};


Hash.prototype.digest = function digest(outputEncoding) {
  outputEncoding = outputEncoding || exports.DEFAULT_ENCODING;
  // Explicit conversion for backward compatibility.
  return this._handle.digest(`${outputEncoding}`);
};


exports.createHmac = exports.Hmac = Hmac;

function Hmac(hmac, key, options) {
  if (!(this instanceof Hmac))
    return new Hmac(hmac, key, options);
  this._handle = new binding.Hmac();
  this._handle.init(hmac, toBuf(key));
  LazyTransform.call(this, options);
}

util.inherits(Hmac, LazyTransform);

Hmac.prototype.update = Hash.prototype.update;
Hmac.prototype.digest = Hash.prototype.digest;
Hmac.prototype._flush = Hash.prototype._flush;
Hmac.prototype._transform = Hash.prototype._transform;


function getDecoder(decoder, encoding) {
  encoding = internalUtil.normalizeEncoding(encoding);
  decoder = decoder || new StringDecoder(encoding);
  assert(decoder.encoding === encoding, 'Cannot change encoding');
  return decoder;
}


exports.createCipher = exports.Cipher = Cipher;
function Cipher(cipher, password, options) {
  if (!(this instanceof Cipher))
    return new Cipher(cipher, password, options);
  this._handle = new binding.CipherBase(true);

  this._handle.init(cipher, toBuf(password));
  this._decoder = null;

  LazyTransform.call(this, options);
}

util.inherits(Cipher, LazyTransform);

Cipher.prototype._transform = function _transform(chunk, encoding, callback) {
  this.push(this._handle.update(chunk, encoding));
  callback();
};

Cipher.prototype._flush = function _flush(callback) {
  try {
    this.push(this._handle.final());
  } catch (e) {
    callback(e);
    return;
  }
  callback();
};

Cipher.prototype.update = function update(data, inputEncoding, outputEncoding) {
  inputEncoding = inputEncoding || exports.DEFAULT_ENCODING;
  outputEncoding = outputEncoding || exports.DEFAULT_ENCODING;

  var ret = this._handle.update(data, inputEncoding);

  if (outputEncoding && outputEncoding !== 'buffer') {
    this._decoder = getDecoder(this._decoder, outputEncoding);
    ret = this._decoder.write(ret);
  }

  return ret;
};


Cipher.prototype.final = function final(outputEncoding) {
  outputEncoding = outputEncoding || exports.DEFAULT_ENCODING;
  var ret = this._handle.final();

  if (outputEncoding && outputEncoding !== 'buffer') {
    this._decoder = getDecoder(this._decoder, outputEncoding);
    ret = this._decoder.end(ret);
  }

  return ret;
};


Cipher.prototype.setAutoPadding = function setAutoPadding(ap) {
  this._handle.setAutoPadding(ap);
  return this;
};

Cipher.prototype.getAuthTag = function getAuthTag() {
  return this._handle.getAuthTag();
};


Cipher.prototype.setAuthTag = function setAuthTag(tagbuf) {
  this._handle.setAuthTag(tagbuf);
  return this;
};

Cipher.prototype.setAAD = function setAAD(aadbuf) {
  this._handle.setAAD(aadbuf);
  return this;
};

exports.createCipheriv = exports.Cipheriv = Cipheriv;
function Cipheriv(cipher, key, iv, options) {
  if (!(this instanceof Cipheriv))
    return new Cipheriv(cipher, key, iv, options);
  this._handle = new binding.CipherBase(true);
  this._handle.initiv(cipher, toBuf(key), toBuf(iv));
  this._decoder = null;

  LazyTransform.call(this, options);
}

util.inherits(Cipheriv, LazyTransform);

Cipheriv.prototype._transform = Cipher.prototype._transform;
Cipheriv.prototype._flush = Cipher.prototype._flush;
Cipheriv.prototype.update = Cipher.prototype.update;
Cipheriv.prototype.final = Cipher.prototype.final;
Cipheriv.prototype.setAutoPadding = Cipher.prototype.setAutoPadding;
Cipheriv.prototype.getAuthTag = Cipher.prototype.getAuthTag;
Cipheriv.prototype.setAuthTag = Cipher.prototype.setAuthTag;
Cipheriv.prototype.setAAD = Cipher.prototype.setAAD;

exports.createDecipher = exports.Decipher = Decipher;
function Decipher(cipher, password, options) {
  if (!(this instanceof Decipher))
    return new Decipher(cipher, password, options);

  this._handle = new binding.CipherBase(false);
  this._handle.init(cipher, toBuf(password));
  this._decoder = null;

  LazyTransform.call(this, options);
}

util.inherits(Decipher, LazyTransform);

Decipher.prototype._transform = Cipher.prototype._transform;
Decipher.prototype._flush = Cipher.prototype._flush;
Decipher.prototype.update = Cipher.prototype.update;
Decipher.prototype.final = Cipher.prototype.final;
Decipher.prototype.finaltol = Cipher.prototype.final;
Decipher.prototype.setAutoPadding = Cipher.prototype.setAutoPadding;
Decipher.prototype.getAuthTag = Cipher.prototype.getAuthTag;
Decipher.prototype.setAuthTag = Cipher.prototype.setAuthTag;
Decipher.prototype.setAAD = Cipher.prototype.setAAD;


exports.createDecipheriv = exports.Decipheriv = Decipheriv;
function Decipheriv(cipher, key, iv, options) {
  if (!(this instanceof Decipheriv))
    return new Decipheriv(cipher, key, iv, options);

  this._handle = new binding.CipherBase(false);
  this._handle.initiv(cipher, toBuf(key), toBuf(iv));
  this._decoder = null;

  LazyTransform.call(this, options);
}

util.inherits(Decipheriv, LazyTransform);

Decipheriv.prototype._transform = Cipher.prototype._transform;
Decipheriv.prototype._flush = Cipher.prototype._flush;
Decipheriv.prototype.update = Cipher.prototype.update;
Decipheriv.prototype.final = Cipher.prototype.final;
Decipheriv.prototype.finaltol = Cipher.prototype.final;
Decipheriv.prototype.setAutoPadding = Cipher.prototype.setAutoPadding;
Decipheriv.prototype.getAuthTag = Cipher.prototype.getAuthTag;
Decipheriv.prototype.setAuthTag = Cipher.prototype.setAuthTag;
Decipheriv.prototype.setAAD = Cipher.prototype.setAAD;


exports.createSign = exports.Sign = Sign;
function Sign(algorithm, options) {
  if (!(this instanceof Sign))
    return new Sign(algorithm, options);
  this._handle = new binding.Sign();
  this._handle.init(algorithm);

  stream.Writable.call(this, options);
}

util.inherits(Sign, stream.Writable);

Sign.prototype._write = function _write(chunk, encoding, callback) {
  this._handle.update(chunk, encoding);
  callback();
};

Sign.prototype.update = Hash.prototype.update;

Sign.prototype.sign = function sign(options, encoding) {
  if (!options)
    throw new Error('No key provided to sign');

  var key = options.key || options;
  var passphrase = options.passphrase || null;

  // Options specific to RSA
  var rsaPadding = constants.RSA_PKCS1_PADDING;
  if (options.hasOwnProperty('padding')) {
    if (options.padding === options.padding >> 0) {
      rsaPadding = options.padding;
    } else {
      throw new TypeError('padding must be an integer');
    }
  }

  var pssSaltLength = constants.RSA_PSS_SALTLEN_AUTO;
  if (options.hasOwnProperty('saltLength')) {
    if (options.saltLength === options.saltLength >> 0) {
      pssSaltLength = options.saltLength;
    } else {
      throw new TypeError('saltLength must be an integer');
    }
  }

  var ret = this._handle.sign(toBuf(key), null, passphrase, rsaPadding,
                              pssSaltLength);

  encoding = encoding || exports.DEFAULT_ENCODING;
  if (encoding && encoding !== 'buffer')
    ret = ret.toString(encoding);

  return ret;
};


exports.createVerify = exports.Verify = Verify;
function Verify(algorithm, options) {
  if (!(this instanceof Verify))
    return new Verify(algorithm, options);

  this._handle = new binding.Verify();
  this._handle.init(algorithm);

  stream.Writable.call(this, options);
}

util.inherits(Verify, stream.Writable);

Verify.prototype._write = Sign.prototype._write;
Verify.prototype.update = Sign.prototype.update;

Verify.prototype.verify = function verify(options, signature, sigEncoding) {
  var key = options.key || options;
  sigEncoding = sigEncoding || exports.DEFAULT_ENCODING;

  // Options specific to RSA
  var rsaPadding = constants.RSA_PKCS1_PADDING;
  if (options.hasOwnProperty('padding')) {
    if (options.padding === options.padding >> 0) {
      rsaPadding = options.padding;
    } else {
      throw new TypeError('padding must be an integer');
    }
  }

  var pssSaltLength = constants.RSA_PSS_SALTLEN_AUTO;
  if (options.hasOwnProperty('saltLength')) {
    if (options.saltLength === options.saltLength >> 0) {
      pssSaltLength = options.saltLength;
    } else {
      throw new TypeError('saltLength must be an integer');
    }
  }

  return this._handle.verify(toBuf(key), toBuf(signature, sigEncoding), null,
                             rsaPadding, pssSaltLength);
};

function rsaPublic(method, defaultPadding) {
  return function(options, buffer) {
    var key = options.key || options;
    var padding = options.padding || defaultPadding;
    var passphrase = options.passphrase || null;
    return method(toBuf(key), buffer, padding, passphrase);
  };
}

function rsaPrivate(method, defaultPadding) {
  return function(options, buffer) {
    var key = options.key || options;
    var passphrase = options.passphrase || null;
    var padding = options.padding || defaultPadding;
    return method(toBuf(key), buffer, padding, passphrase);
  };
}

exports.publicEncrypt = rsaPublic(binding.publicEncrypt,
                                  constants.RSA_PKCS1_OAEP_PADDING);
exports.publicDecrypt = rsaPublic(binding.publicDecrypt,
                                  constants.RSA_PKCS1_PADDING);
exports.privateEncrypt = rsaPrivate(binding.privateEncrypt,
                                    constants.RSA_PKCS1_PADDING);
exports.privateDecrypt = rsaPrivate(binding.privateDecrypt,
                                    constants.RSA_PKCS1_OAEP_PADDING);


exports.createDiffieHellman = exports.DiffieHellman = DiffieHellman;

function DiffieHellman(sizeOrKey, keyEncoding, generator, genEncoding) {
  if (!(this instanceof DiffieHellman))
    return new DiffieHellman(sizeOrKey, keyEncoding, generator, genEncoding);

  if (!(sizeOrKey instanceof Buffer) &&
      typeof sizeOrKey !== 'number' &&
      typeof sizeOrKey !== 'string')
    throw new TypeError('First argument should be number, string or Buffer');

  if (keyEncoding) {
    if (typeof keyEncoding !== 'string' ||
        (!Buffer.isEncoding(keyEncoding) && keyEncoding !== 'buffer')) {
      genEncoding = generator;
      generator = keyEncoding;
      keyEncoding = false;
    }
  }

  keyEncoding = keyEncoding || exports.DEFAULT_ENCODING;
  genEncoding = genEncoding || exports.DEFAULT_ENCODING;

  if (typeof sizeOrKey !== 'number')
    sizeOrKey = toBuf(sizeOrKey, keyEncoding);

  if (!generator)
    generator = DH_GENERATOR;
  else if (typeof generator !== 'number')
    generator = toBuf(generator, genEncoding);

  this._handle = new binding.DiffieHellman(sizeOrKey, generator);
  Object.defineProperty(this, 'verifyError', {
    enumerable: true,
    value: this._handle.verifyError,
    writable: false
  });
}


exports.DiffieHellmanGroup =
    exports.createDiffieHellmanGroup =
    exports.getDiffieHellman = DiffieHellmanGroup;

function DiffieHellmanGroup(name) {
  if (!(this instanceof DiffieHellmanGroup))
    return new DiffieHellmanGroup(name);
  this._handle = new binding.DiffieHellmanGroup(name);
  Object.defineProperty(this, 'verifyError', {
    enumerable: true,
    value: this._handle.verifyError,
    writable: false
  });
}


DiffieHellmanGroup.prototype.generateKeys =
    DiffieHellman.prototype.generateKeys =
    dhGenerateKeys;

function dhGenerateKeys(encoding) {
  var keys = this._handle.generateKeys();
  encoding = encoding || exports.DEFAULT_ENCODING;
  if (encoding && encoding !== 'buffer')
    keys = keys.toString(encoding);
  return keys;
}


DiffieHellmanGroup.prototype.computeSecret =
    DiffieHellman.prototype.computeSecret =
    dhComputeSecret;

function dhComputeSecret(key, inEnc, outEnc) {
  inEnc = inEnc || exports.DEFAULT_ENCODING;
  outEnc = outEnc || exports.DEFAULT_ENCODING;
  var ret = this._handle.computeSecret(toBuf(key, inEnc));
  if (outEnc && outEnc !== 'buffer')
    ret = ret.toString(outEnc);
  return ret;
}


DiffieHellmanGroup.prototype.getPrime =
    DiffieHellman.prototype.getPrime =
    dhGetPrime;

function dhGetPrime(encoding) {
  var prime = this._handle.getPrime();
  encoding = encoding || exports.DEFAULT_ENCODING;
  if (encoding && encoding !== 'buffer')
    prime = prime.toString(encoding);
  return prime;
}


DiffieHellmanGroup.prototype.getGenerator =
    DiffieHellman.prototype.getGenerator =
    dhGetGenerator;

function dhGetGenerator(encoding) {
  var generator = this._handle.getGenerator();
  encoding = encoding || exports.DEFAULT_ENCODING;
  if (encoding && encoding !== 'buffer')
    generator = generator.toString(encoding);
  return generator;
}


DiffieHellmanGroup.prototype.getPublicKey =
    DiffieHellman.prototype.getPublicKey =
    dhGetPublicKey;

function dhGetPublicKey(encoding) {
  var key = this._handle.getPublicKey();
  encoding = encoding || exports.DEFAULT_ENCODING;
  if (encoding && encoding !== 'buffer')
    key = key.toString(encoding);
  return key;
}


DiffieHellmanGroup.prototype.getPrivateKey =
    DiffieHellman.prototype.getPrivateKey =
    dhGetPrivateKey;

function dhGetPrivateKey(encoding) {
  var key = this._handle.getPrivateKey();
  encoding = encoding || exports.DEFAULT_ENCODING;
  if (encoding && encoding !== 'buffer')
    key = key.toString(encoding);
  return key;
}


DiffieHellman.prototype.setPublicKey = function setPublicKey(key, encoding) {
  encoding = encoding || exports.DEFAULT_ENCODING;
  this._handle.setPublicKey(toBuf(key, encoding));
  return this;
};


DiffieHellman.prototype.setPrivateKey = function setPrivateKey(key, encoding) {
  encoding = encoding || exports.DEFAULT_ENCODING;
  this._handle.setPrivateKey(toBuf(key, encoding));
  return this;
};


exports.createECDH = exports.ECDH = ECDH;
function ECDH(curve) {
  if (!(this instanceof ECDH))
    return new ECDH(curve);
  if (typeof curve !== 'string')
    throw new TypeError('"curve" argument should be a string');

  this._handle = new binding.ECDH(curve);
}

ECDH.prototype.computeSecret = DiffieHellman.prototype.computeSecret;
ECDH.prototype.setPrivateKey = DiffieHellman.prototype.setPrivateKey;
ECDH.prototype.setPublicKey = DiffieHellman.prototype.setPublicKey;
ECDH.prototype.getPrivateKey = DiffieHellman.prototype.getPrivateKey;

ECDH.prototype.generateKeys = function generateKeys(encoding, format) {
  this._handle.generateKeys();

  return this.getPublicKey(encoding, format);
};

ECDH.prototype.getPublicKey = function getPublicKey(encoding, format) {
  var f;
  if (format) {
    if (typeof format === 'number')
      f = format;
    if (format === 'compressed')
      f = constants.POINT_CONVERSION_COMPRESSED;
    else if (format === 'hybrid')
      f = constants.POINT_CONVERSION_HYBRID;
    // Default
    else if (format === 'uncompressed')
      f = constants.POINT_CONVERSION_UNCOMPRESSED;
    else
      throw new TypeError('Bad format: ' + format);
  } else {
    f = constants.POINT_CONVERSION_UNCOMPRESSED;
  }
  var key = this._handle.getPublicKey(f);
  encoding = encoding || exports.DEFAULT_ENCODING;
  if (encoding && encoding !== 'buffer')
    key = key.toString(encoding);
  return key;
};


const pbkdf2DeprecationWarning =
    internalUtil.deprecate(() => {}, 'crypto.pbkdf2 without specifying' +
      ' a digest is deprecated. Please specify a digest');


exports.pbkdf2 = function(password,
                          salt,
                          iterations,
                          keylen,
                          digest,
                          callback) {
  if (typeof digest === 'function') {
    callback = digest;
    digest = undefined;
    pbkdf2DeprecationWarning();
  }

  if (typeof callback !== 'function')
    throw new Error('No callback provided to pbkdf2');

  return pbkdf2(password, salt, iterations, keylen, digest, callback);
};


exports.pbkdf2Sync = function(password, salt, iterations, keylen, digest) {
  if (typeof digest === 'undefined') {
    digest = undefined;
    pbkdf2DeprecationWarning();
  }
  return pbkdf2(password, salt, iterations, keylen, digest);
};


function pbkdf2(password, salt, iterations, keylen, digest, callback) {
  password = toBuf(password);
  salt = toBuf(salt);

  if (exports.DEFAULT_ENCODING === 'buffer')
    return binding.PBKDF2(password, salt, iterations, keylen, digest, callback);

  // at this point, we need to handle encodings.
  var encoding = exports.DEFAULT_ENCODING;
  if (callback) {
    function next(er, ret) {
      if (ret)
        ret = ret.toString(encoding);
      callback(er, ret);
    }
    binding.PBKDF2(password, salt, iterations, keylen, digest, next);
  } else {
    var ret = binding.PBKDF2(password, salt, iterations, keylen, digest);
    return ret.toString(encoding);
  }
}


exports.Certificate = Certificate;

function Certificate() {
  if (!(this instanceof Certificate))
    return new Certificate();
}


Certificate.prototype.verifySpkac = function verifySpkac(object) {
  return binding.certVerifySpkac(object);
};


Certificate.prototype.exportPublicKey =
  function exportPublicKey(object, encoding) {
    return binding.certExportPublicKey(toBuf(object, encoding));
  };


Certificate.prototype.exportChallenge =
  function exportChallenge(object, encoding) {
    return binding.certExportChallenge(toBuf(object, encoding));
  };


exports.setEngine = function setEngine(id, flags) {
  if (typeof id !== 'string')
    throw new TypeError('"id" argument should be a string');

  if (flags && typeof flags !== 'number')
    throw new TypeError('"flags" argument should be a number, if present');
  flags = flags >>> 0;

  // Use provided engine for everything by default
  if (flags === 0)
    flags = constants.ENGINE_METHOD_ALL;

  return binding.setEngine(id, flags);
};

const kMaxUint32 = Math.pow(2, 32) - 1;

function randomFillSync(buf, offset = 0, size) {
  if (!isUint8Array(buf)) {
    throw new TypeError('"buf" argument must be a Buffer or Uint8Array');
  }

  assertOffset(offset, buf.length);

  if (size === undefined) size = buf.length - offset;

  assertSize(size, offset, buf.length);

  return binding.randomFill(buf, offset, size);
}
exports.randomFillSync = randomFillSync;

function randomFill(buf, offset, size, cb) {
  if (!isUint8Array(buf)) {
    throw new TypeError('"buf" argument must be a Buffer or Uint8Array');
  }

  if (typeof offset === 'function') {
    cb = offset;
    offset = 0;
    size = buf.length;
  } else if (typeof size === 'function') {
    cb = size;
    size = buf.length - offset;
  } else if (typeof cb !== 'function') {
    throw new TypeError('"cb" argument must be a function');
  }

  assertOffset(offset, buf.length);
  assertSize(size, offset, buf.length);

  return binding.randomFill(buf, offset, size, cb);
}
exports.randomFill = randomFill;

function assertOffset(offset, length) {
  if (typeof offset !== 'number' || offset !== offset) {
    throw new TypeError('offset must be a number');
  }

  if (offset > kMaxUint32 || offset < 0) {
    throw new TypeError('offset must be a uint32');
  }

  if (offset > kBufferMaxLength || offset > length) {
    throw new RangeError('offset out of range');
  }
}

function assertSize(size, offset, length) {
  if (typeof size !== 'number' || size !== size) {
    throw new TypeError('size must be a number');
  }

  if (size > kMaxUint32 || size < 0) {
    throw new TypeError('size must be a uint32');
  }

  if (size + offset > length || size > kBufferMaxLength) {
    throw new RangeError('buffer too small');
  }
}

exports.randomBytes = exports.pseudoRandomBytes = randomBytes;

exports.rng = exports.prng = randomBytes;

exports.getCiphers = internalUtil.cachedResult(
  () => internalUtil.filterDuplicateStrings(getCiphers())
);

exports.getHashes = internalUtil.cachedResult(
  () => internalUtil.filterDuplicateStrings(getHashes())
);

exports.getCurves = internalUtil.cachedResult(
  () => internalUtil.filterDuplicateStrings(getCurves())
);

Object.defineProperty(exports, 'fips', {
  get: getFipsCrypto,
  set: setFipsCrypto
});

exports.timingSafeEqual = timingSafeEqual;

// Legacy API
Object.defineProperty(exports, 'createCredentials', {
  configurable: true,
  enumerable: true,
  get: internalUtil.deprecate(function() {
    return require('tls').createSecureContext;
  }, 'crypto.createCredentials is deprecated. ' +
     'Use tls.createSecureContext instead.')
});

Object.defineProperty(exports, 'Credentials', {
  configurable: true,
  enumerable: true,
  get: internalUtil.deprecate(function() {
    return require('tls').SecureContext;
  }, 'crypto.Credentials is deprecated. ' +
     'Use tls.SecureContext instead.')
});