Crypto

The crypto module provides cryptographic functionality that includes a set of wrappers for OpenSSL's hash, HMAC, cipher, decipher, sign, and verify functions.

Use require('crypto') to access this module.

const crypto = require('crypto');

const secret = 'abcdefg';
const hash = crypto.createHmac('sha256', secret)
                   .update('I love cupcakes')
                   .digest('hex');
console.log(hash);
// Prints:
//   c0fa1bc00531bd78ef38c628449c5102aeabd49b5dc3a2a516ea6ea959d6658e

Determining if crypto support is unavailable

It is possible for Node.js to be built without including support for the crypto module. In such cases, calling require('crypto') will result in an error being thrown.

let crypto;
try {
  crypto = require('crypto');
} catch (err) {
  console.log('crypto support is disabled!');
}

Class: Certificate

SPKAC is a Certificate Signing Request mechanism originally implemented by Netscape and was specified formally as part of HTML5's keygen element.

Note that <keygen> is deprecated since HTML 5.2 and new projects should not use this element anymore.

The crypto module provides the Certificate class for working with SPKAC data. The most common usage is handling output generated by the HTML5 <keygen> element. Node.js uses OpenSSL's SPKAC implementation internally.

Certificate.exportChallenge(spkac)

• spkac <string> | <Buffer> | <TypedArray> | <DataView>
• Returns: <Buffer> The challenge component of the spkac data structure, which includes a public key and a challenge.

const { Certificate } = require('crypto');
const spkac = getSpkacSomehow();
const challenge = Certificate.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string

Certificate.exportPublicKey(spkac[, encoding])

• spkac <string> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the spkac string.
• Returns: <Buffer> The public key component of the spkac data structure, which includes a public key and a challenge.

const { Certificate } = require('crypto');
const spkac = getSpkacSomehow();
const publicKey = Certificate.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>

Certificate.verifySpkac(spkac)

• spkac <Buffer> | <TypedArray> | <DataView>
• Returns: <boolean> true if the given spkac data structure is valid, false otherwise.

const { Certificate } = require('crypto');
const spkac = getSpkacSomehow();
console.log(Certificate.verifySpkac(Buffer.from(spkac)));
// Prints: true or false

Legacy API

As a still supported legacy interface, it is possible (but not recommended) to create new instances of the crypto.Certificate class as illustrated in the examples below.

new crypto.Certificate()

Instances of the Certificate class can be created using the new keyword or by calling crypto.Certificate() as a function:

const crypto = require('crypto');

const cert1 = new crypto.Certificate();
const cert2 = crypto.Certificate();

certificate.exportChallenge(spkac)

• spkac <string> | <Buffer> | <TypedArray> | <DataView>
• Returns: <Buffer> The challenge component of the spkac data structure, which includes a public key and a challenge.

const cert = require('crypto').Certificate();
const spkac = getSpkacSomehow();
const challenge = cert.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string

certificate.exportPublicKey(spkac)

• spkac <string> | <Buffer> | <TypedArray> | <DataView>
• Returns: <Buffer> The public key component of the spkac data structure, which includes a public key and a challenge.

const cert = require('crypto').Certificate();
const spkac = getSpkacSomehow();
const publicKey = cert.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>

certificate.verifySpkac(spkac)

• spkac <Buffer> | <TypedArray> | <DataView>
• Returns: <boolean> true if the given spkac data structure is valid, false otherwise.

const cert = require('crypto').Certificate();
const spkac = getSpkacSomehow();
console.log(cert.verifySpkac(Buffer.from(spkac)));
// Prints: true or false

Class: Cipher

Instances of the Cipher class are used to encrypt data. The class can be used in one of two ways:

• As a stream that is both readable and writable, where plain unencrypted data is written to produce encrypted data on the readable side, or
• Using the cipher.update() and cipher.final() methods to produce the encrypted data.

The crypto.createCipher() or crypto.createCipheriv() methods are used to create Cipher instances. Cipher objects are not to be created directly using the new keyword.

Example: Using Cipher objects as streams:

const crypto = require('crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Key length is dependent on the algorithm. In this case for aes192, it is
// 24 bytes (192 bits).
// Use async `crypto.scrypt()` instead.
const key = crypto.scryptSync(password, 'salt', 24);
// Use `crypto.randomBytes()` to generate a random iv instead of the static iv
// shown here.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const cipher = crypto.createCipheriv(algorithm, key, iv);

let encrypted = '';
cipher.on('readable', () => {
  let chunk;
  while (null !== (chunk = cipher.read())) {
    encrypted += chunk.toString('hex');
  }
});
cipher.on('end', () => {
  console.log(encrypted);
  // Prints: e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa
});

cipher.write('some clear text data');
cipher.end();

Example: Using Cipher and piped streams:

const crypto = require('crypto');
const fs = require('fs');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = crypto.scryptSync(password, 'salt', 24);
// Use `crypto.randomBytes()` to generate a random iv instead of the static iv
// shown here.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const cipher = crypto.createCipheriv(algorithm, key, iv);

const input = fs.createReadStream('test.js');
const output = fs.createWriteStream('test.enc');

input.pipe(cipher).pipe(output);

Example: Using the cipher.update() and cipher.final() methods:

const crypto = require('crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = crypto.scryptSync(password, 'salt', 24);
// Use `crypto.randomBytes` to generate a random iv instead of the static iv
// shown here.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const cipher = crypto.createCipheriv(algorithm, key, iv);

let encrypted = cipher.update('some clear text data', 'utf8', 'hex');
encrypted += cipher.final('hex');
console.log(encrypted);
// Prints: e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa

cipher.final([outputEncoding])

• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string> Any remaining enciphered contents. If outputEncoding is specified, a string is returned. If an outputEncoding is not provided, a Buffer is returned.

Once the cipher.final() method has been called, the Cipher object can no longer be used to encrypt data. Attempts to call cipher.final() more than once will result in an error being thrown.

cipher.setAAD(buffer[, options])

• buffer <Buffer>

• options <Object> stream.transform options

  • plaintextLength <number>
• Returns: <Cipher> for method chaining.

When using an authenticated encryption mode (GCM, CCM and OCB are currently supported), the cipher.setAAD() method sets the value used for the additional authenticated data (AAD) input parameter.

The options argument is optional for GCM and OCB. When using CCM, the plaintextLength option must be specified and its value must match the length of the plaintext in bytes. See CCM mode.

The cipher.setAAD() method must be called before cipher.update().

cipher.getAuthTag()

• Returns: <Buffer> When using an authenticated encryption mode (GCM, CCM and OCB are currently supported), the cipher.getAuthTag() method returns a Buffer containing the authentication tag that has been computed from the given data.

The cipher.getAuthTag() method should only be called after encryption has been completed using the cipher.final() method.

cipher.setAutoPadding([autoPadding])

• autoPadding <boolean> Default: true
• Returns: <Cipher> for method chaining.

When using block encryption algorithms, the Cipher class will automatically add padding to the input data to the appropriate block size. To disable the default padding call cipher.setAutoPadding(false).

When autoPadding is false, the length of the entire input data must be a multiple of the cipher's block size or cipher.final() will throw an error. Disabling automatic padding is useful for non-standard padding, for instance using 0x0 instead of PKCS padding.

The cipher.setAutoPadding() method must be called before cipher.final().

cipher.update(data[, inputEncoding][, outputencoding])

• data <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the data.
• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Updates the cipher with data. If the inputEncoding argument is given, the data argument is a string using the specified encoding. If the inputEncoding argument is not given, data must be a Buffer, TypedArray, or DataView. If data is a Buffer, TypedArray, or DataView, then inputEncoding is ignored.

The outputEncoding specifies the output format of the enciphered data. If the outputEncoding is specified, a string using the specified encoding is returned. If no outputEncoding is provided, a Buffer is returned.

The cipher.update() method can be called multiple times with new data until cipher.final() is called. Calling cipher.update() after cipher.final() will result in an error being thrown.

Class: Decipher

Instances of the Decipher class are used to decrypt data. The class can be used in one of two ways:

• As a stream that is both readable and writable, where plain encrypted data is written to produce unencrypted data on the readable side, or
• Using the decipher.update() and decipher.final() methods to produce the unencrypted data.

The crypto.createDecipher() or crypto.createDecipheriv() methods are used to create Decipher instances. Decipher objects are not to be created directly using the new keyword.

Example: Using Decipher objects as streams:

const crypto = require('crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Key length is dependent on the algorithm. In this case for aes192, it is
// 24 bytes (192 bits).
// Use the async `crypto.scrypt()` instead.
const key = crypto.scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = crypto.createDecipheriv(algorithm, key, iv);

let decrypted = '';
decipher.on('readable', () => {
  while (null !== (chunk = decipher.read())) {
    decrypted += chunk.toString('utf8');
  }
});
decipher.on('end', () => {
  console.log(decrypted);
  // Prints: some clear text data
});

// Encrypted with same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
decipher.write(encrypted, 'hex');
decipher.end();

Example: Using Decipher and piped streams:

const crypto = require('crypto');
const fs = require('fs');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = crypto.scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = crypto.createDecipheriv(algorithm, key, iv);

const input = fs.createReadStream('test.enc');
const output = fs.createWriteStream('test.js');

input.pipe(decipher).pipe(output);

Example: Using the decipher.update() and decipher.final() methods:

const crypto = require('crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = crypto.scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = crypto.createDecipheriv(algorithm, key, iv);

// Encrypted using same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
let decrypted = decipher.update(encrypted, 'hex', 'utf8');
decrypted += decipher.final('utf8');
console.log(decrypted);
// Prints: some clear text data

decipher.final([outputEncoding])

• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string> Any remaining deciphered contents. If outputEncoding is specified, a string is returned. If an outputEncoding is not provided, a Buffer is returned.

Once the decipher.final() method has been called, the Decipher object can no longer be used to decrypt data. Attempts to call decipher.final() more than once will result in an error being thrown.

decipher.setAAD(buffer[, options])

• buffer <Buffer> | <TypedArray> | <DataView>

• options <Object> stream.transform options

  • plaintextLength <number>
• Returns: <Decipher> for method chaining.

When using an authenticated encryption mode (GCM, CCM and OCB are currently supported), the decipher.setAAD() method sets the value used for the additional authenticated data (AAD) input parameter.

The options argument is optional for GCM. When using CCM, the plaintextLength option must be specified and its value must match the length of the plaintext in bytes. See CCM mode.

The decipher.setAAD() method must be called before decipher.update().

decipher.setAuthTag(buffer)

• buffer <Buffer> | <TypedArray> | <DataView>
• Returns: <Decipher> for method chaining.

When using an authenticated encryption mode (GCM, CCM and OCB are currently supported), the decipher.setAuthTag() method is used to pass in the received authentication tag. If no tag is provided, or if the cipher text has been tampered with, decipher.final() will throw, indicating that the cipher text should be discarded due to failed authentication.

Note that this Node.js version does not verify the length of GCM authentication tags. Such a check must be implemented by applications and is crucial to the authenticity of the encrypted data, otherwise, an attacker can use an arbitrarily short authentication tag to increase the chances of successfully passing authentication (up to 0.39%). It is highly recommended to associate one of the values 16, 15, 14, 13, 12, 8 or 4 bytes with each key, and to only permit authentication tags of that length, see NIST SP 800-38D.

The decipher.setAuthTag() method must be called before decipher.final().

decipher.setAutoPadding([autoPadding])

• autoPadding <boolean> Default: true
• Returns: <Decipher> for method chaining.

When data has been encrypted without standard block padding, calling decipher.setAutoPadding(false) will disable automatic padding to prevent decipher.final() from checking for and removing padding.

Turning auto padding off will only work if the input data's length is a multiple of the ciphers block size.

The decipher.setAutoPadding() method must be called before decipher.final().

decipher.update(data[, inputEncoding][, outputencoding])

• data <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the data string.
• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Updates the decipher with data. If the inputEncoding argument is given, the data argument is a string using the specified encoding. If the inputEncoding argument is not given, data must be a Buffer. If data is a Buffer then inputEncoding is ignored.

The outputEncoding specifies the output format of the enciphered data. If the outputEncoding is specified, a string using the specified encoding is returned. If no outputEncoding is provided, a Buffer is returned.

The decipher.update() method can be called multiple times with new data until decipher.final() is called. Calling decipher.update() after decipher.final() will result in an error being thrown.

Class: DiffieHellman

The DiffieHellman class is a utility for creating Diffie-Hellman key exchanges.

Instances of the DiffieHellman class can be created using the crypto.createDiffieHellman() function.

const crypto = require('crypto');
const assert = require('assert');

// Generate Alice's keys...
const alice = crypto.createDiffieHellman(2048);
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = crypto.createDiffieHellman(alice.getPrime(), alice.getGenerator());
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

// OK
assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));

diffieHellman.computeSecret(otherPublicKey[, inputEncoding][, outputencoding])

• otherPublicKey <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of an otherPublicKey string.
• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Computes the shared secret using otherPublicKey as the other party's public key and returns the computed shared secret. The supplied key is interpreted using the specified inputEncoding, and secret is encoded using specified outputEncoding. If the inputEncoding is not provided, otherPublicKey is expected to be a Buffer, TypedArray, or DataView.

If outputEncoding is given a string is returned; otherwise, a Buffer is returned.

diffieHellman.generateKeys(encoding)

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Generates private and public Diffie-Hellman key values, and returns the public key in the specified encoding. This key should be transferred to the other party. If encoding is provided a string is returned; otherwise a Buffer is returned.

diffieHellman.getGenerator(encoding)

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Returns the Diffie-Hellman generator in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

diffieHellman.getPrime(encoding)

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Returns the Diffie-Hellman prime in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

diffieHellman.getPrivateKey(encoding)

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Returns the Diffie-Hellman private key in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

diffieHellman.getPublicKey(encoding)

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Returns the Diffie-Hellman public key in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

diffieHellman.setPrivateKey(privateKey[, encoding])

• privateKey <string> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the privateKey string.

Sets the Diffie-Hellman private key. If the encoding argument is provided, privateKey is expected to be a string. If no encoding is provided, privateKey is expected to be a Buffer, TypedArray, or DataView.

diffieHellman.setPublicKey(publicKey[, encoding])

• publicKey <string> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the publicKey string.

Sets the Diffie-Hellman public key. If the encoding argument is provided, publicKey is expected to be a string. If no encoding is provided, publicKey is expected to be a Buffer, TypedArray, or DataView.

diffieHellman.verifyError

A bit field containing any warnings and/or errors resulting from a check performed during initialization of the DiffieHellman object.

The following values are valid for this property (as defined in constants module):

• DH_CHECK_P_NOT_SAFE_PRIME
• DH_CHECK_P_NOT_PRIME
• DH_UNABLE_TO_CHECK_GENERATOR
• DH_NOT_SUITABLE_GENERATOR

Class: ECDH

The ECDH class is a utility for creating Elliptic Curve Diffie-Hellman (ECDH) key exchanges.

Instances of the ECDH class can be created using the crypto.createECDH() function.

const crypto = require('crypto');
const assert = require('assert');

// Generate Alice's keys...
const alice = crypto.createECDH('secp521r1');
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = crypto.createECDH('secp521r1');
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));
// OK

Class Method: ECDH.convertKey(key, curve[, inputEncoding[, outputEncoding[, format]]])

• key <string> | <Buffer> | <TypedArray> | <DataView>
• curve <string>
• inputEncoding <string> The encoding of the key string.
• outputEncoding <string> The encoding of the return value.
• format <string> Default: 'uncompressed'
• Returns: <Buffer> | <string>

Converts the EC Diffie-Hellman public key specified by key and curve to the format specified by format. The format argument specifies point encoding and can be 'compressed', 'uncompressed' or 'hybrid'. The supplied key is interpreted using the specified inputEncoding, and the returned key is encoded using the specified outputEncoding.

Use crypto.getCurves() to obtain a list of available curve names. On recent OpenSSL releases, openssl ecparam -list_curves will also display the name and description of each available elliptic curve.

If format is not specified the point will be returned in 'uncompressed' format.

If the inputEncoding is not provided, key is expected to be a Buffer, TypedArray, or DataView.

Example (uncompressing a key):

const { createECDH, ECDH } = require('crypto');

const ecdh = createECDH('secp256k1');
ecdh.generateKeys();

const compressedKey = ecdh.getPublicKey('hex', 'compressed');

const uncompressedKey = ECDH.convertKey(compressedKey,
                                        'secp256k1',
                                        'hex',
                                        'hex',
                                        'uncompressed');

// the converted key and the uncompressed public key should be the same
console.log(uncompressedKey === ecdh.getPublicKey('hex'));

ecdh.computeSecret(otherPublicKey[, inputEncoding][, outputencoding])

• otherPublicKey <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the otherPublicKey string.
• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Computes the shared secret using otherPublicKey as the other party's public key and returns the computed shared secret. The supplied key is interpreted using specified inputEncoding, and the returned secret is encoded using the specified outputEncoding. If the inputEncoding is not provided, otherPublicKey is expected to be a Buffer, TypedArray, or DataView.

If outputEncoding is given a string will be returned; otherwise a Buffer is returned.

ecdh.computeSecret will throw an ERR_CRYPTO_ECDH_INVALID_PUBLIC_KEY error when otherPublicKey lies outside of the elliptic curve. Since otherPublicKey is usually supplied from a remote user over an insecure network, its recommended for developers to handle this exception accordingly.

ecdh.generateKeys([encoding[, format]])

• encoding <string> The encoding of the return value.
• format <string> Default: 'uncompressed'
• Returns: <Buffer> | <string>

Generates private and public EC Diffie-Hellman key values, and returns the public key in the specified format and encoding. This key should be transferred to the other party.

The format argument specifies point encoding and can be 'compressed' or 'uncompressed'. If format is not specified, the point will be returned in 'uncompressed' format.

If encoding is provided a string is returned; otherwise a Buffer is returned.

ecdh.getPrivateKey(encoding)

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string> The EC Diffie-Hellman in the specified encoding.

If encoding is specified, a string is returned; otherwise a Buffer is returned.

ecdh.getPublicKey([encoding][, format])

• encoding <string> The encoding of the return value.
• format <string> Default: 'uncompressed'
• Returns: <Buffer> | <string> The EC Diffie-Hellman public key in the specified encoding and format.

The format argument specifies point encoding and can be 'compressed' or 'uncompressed'. If format is not specified the point will be returned in 'uncompressed' format.

If encoding is specified, a string is returned; otherwise a Buffer is returned.

ecdh.setPrivateKey(privateKey[, encoding])

• privateKey <string> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the privateKey string.

Sets the EC Diffie-Hellman private key. If encoding is provided, privateKey is expected to be a string; otherwise privateKey is expected to be a Buffer, TypedArray, or DataView.

If privateKey is not valid for the curve specified when the ECDH object was created, an error is thrown. Upon setting the private key, the associated public point (key) is also generated and set in the ECDH object.

ecdh.setPublicKey(publicKey[, encoding])

• publicKey <string> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the publicKey string.

Sets the EC Diffie-Hellman public key. If encoding is provided publicKey is expected to be a string; otherwise a Buffer, TypedArray, or DataView is expected.

Note that there is not normally a reason to call this method because ECDH only requires a private key and the other party's public key to compute the shared secret. Typically either ecdh.generateKeys() or ecdh.setPrivateKey() will be called. The ecdh.setPrivateKey() method attempts to generate the public point/key associated with the private key being set.

Example (obtaining a shared secret):

const crypto = require('crypto');
const alice = crypto.createECDH('secp256k1');
const bob = crypto.createECDH('secp256k1');

// This is a shortcut way of specifying one of Alice's previous private
// keys. It would be unwise to use such a predictable private key in a real
// application.
alice.setPrivateKey(
  crypto.createHash('sha256').update('alice', 'utf8').digest()
);

// Bob uses a newly generated cryptographically strong
// pseudorandom key pair
bob.generateKeys();

const aliceSecret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
const bobSecret = bob.computeSecret(alice.getPublicKey(), null, 'hex');

// aliceSecret and bobSecret should be the same shared secret value
console.log(aliceSecret === bobSecret);

Class: Hash

The Hash class is a utility for creating hash digests of data. It can be used in one of two ways:

• As a stream that is both readable and writable, where data is written to produce a computed hash digest on the readable side, or
• Using the hash.update() and hash.digest() methods to produce the computed hash.

The crypto.createHash() method is used to create Hash instances. Hash objects are not to be created directly using the new keyword.

Example: Using Hash objects as streams:

const crypto = require('crypto');
const hash = crypto.createHash('sha256');

hash.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hash.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
  }
});

hash.write('some data to hash');
hash.end();

Example: Using Hash and piped streams:

const crypto = require('crypto');
const fs = require('fs');
const hash = crypto.createHash('sha256');

const input = fs.createReadStream('test.js');
input.pipe(hash).pipe(process.stdout);

Example: Using the hash.update() and hash.digest() methods:

const crypto = require('crypto');
const hash = crypto.createHash('sha256');

hash.update('some data to hash');
console.log(hash.digest('hex'));
// Prints:
//   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50

hash.digest(encoding)

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Calculates the digest of all of the data passed to be hashed (using the hash.update() method). If encoding is provided a string will be returned; otherwise a Buffer is returned.

The Hash object can not be used again after hash.digest() method has been called. Multiple calls will cause an error to be thrown.

hash.update(data[, inputEncoding])

• data <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the data string.

Updates the hash content with the given data, the encoding of which is given in inputEncoding. If encoding is not provided, and the data is a string, an encoding of 'utf8' is enforced. If data is a Buffer, TypedArray, or DataView, then inputEncoding is ignored.

This can be called many times with new data as it is streamed.

Class: Hmac

The Hmac Class is a utility for creating cryptographic HMAC digests. It can be used in one of two ways:

• As a stream that is both readable and writable, where data is written to produce a computed HMAC digest on the readable side, or
• Using the hmac.update() and hmac.digest() methods to produce the computed HMAC digest.

The crypto.createHmac() method is used to create Hmac instances. Hmac objects are not to be created directly using the new keyword.

Example: Using Hmac objects as streams:

const crypto = require('crypto');
const hmac = crypto.createHmac('sha256', 'a secret');

hmac.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hmac.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
  }
});

hmac.write('some data to hash');
hmac.end();

Example: Using Hmac and piped streams:

const crypto = require('crypto');
const fs = require('fs');
const hmac = crypto.createHmac('sha256', 'a secret');

const input = fs.createReadStream('test.js');
input.pipe(hmac).pipe(process.stdout);

Example: Using the hmac.update() and hmac.digest() methods:

const crypto = require('crypto');
const hmac = crypto.createHmac('sha256', 'a secret');

hmac.update('some data to hash');
console.log(hmac.digest('hex'));
// Prints:
//   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e

hmac.digest(encoding)

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Calculates the HMAC digest of all of the data passed using hmac.update(). If encoding is provided a string is returned; otherwise a Buffer is returned;

The Hmac object can not be used again after hmac.digest() has been called. Multiple calls to hmac.digest() will result in an error being thrown.

hmac.update(data[, inputEncoding])

• data <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the data string.

Updates the Hmac content with the given data, the encoding of which is given in inputEncoding. If encoding is not provided, and the data is a string, an encoding of 'utf8' is enforced. If data is a Buffer, TypedArray, or DataView, then inputEncoding is ignored.

This can be called many times with new data as it is streamed.

Class: Sign

The Sign Class is a utility for generating signatures. It can be used in one of two ways:

• As a writable stream, where data to be signed is written and the sign.sign() method is used to generate and return the signature, or
• Using the sign.update() and sign.sign() methods to produce the signature.

The crypto.createSign() method is used to create Sign instances. The argument is the string name of the hash function to use. Sign objects are not to be created directly using the new keyword.

Example: Using Sign objects as streams:

const crypto = require('crypto');
const sign = crypto.createSign('SHA256');

sign.write('some data to sign');
sign.end();

const privateKey = getPrivateKeySomehow();
console.log(sign.sign(privateKey, 'hex'));
// Prints: the calculated signature using the specified private key and
// SHA-256. For RSA keys, the algorithm is RSASSA-PKCS1-v1_5 (see padding
// parameter below for RSASSA-PSS). For EC keys, the algorithm is ECDSA.

Example: Using the sign.update() and sign.sign() methods:

const crypto = require('crypto');
const sign = crypto.createSign('SHA256');

sign.update('some data to sign');

const privateKey = getPrivateKeySomehow();
console.log(sign.sign(privateKey, 'hex'));
// Prints: the calculated signature

In some cases, a Sign instance can also be created by passing in a signature algorithm name, such as 'RSA-SHA256'. This will use the corresponding digest algorithm. This does not work for all signature algorithms, such as 'ecdsa-with-SHA256'. Use digest names instead.

Example: signing using legacy signature algorithm name

const crypto = require('crypto');
const sign = crypto.createSign('RSA-SHA256');

sign.update('some data to sign');

const privateKey = getPrivateKeySomehow();
console.log(sign.sign(privateKey, 'hex'));
// Prints: the calculated signature

sign.sign(privateKey[, outputEncoding])

• privateKey <string> | <Object>

  • key <string>
  • passphrase <string>
  • padding <integer>
  • saltLength <integer>
• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Calculates the signature on all the data passed through using either sign.update() or sign.write().

The privateKey argument can be an object or a string. If privateKey is a string, it is treated as a raw key with no passphrase. If privateKey is an object, it must contain one or more of the following properties:

• key: <string> - PEM encoded private key (required)

• passphrase: <string> - passphrase for the private key

• padding: <integer> - Optional padding value for RSA, one of the following:

  • crypto.constants.RSA_PKCS1_PADDING (default)
  • crypto.constants.RSA_PKCS1_PSS_PADDING

  Note that RSA_PKCS1_PSS_PADDING will use MGF1 with the same hash function used to sign the message as specified in section 3.1 of RFC 4055.

• saltLength: <integer> - salt length for when padding is RSA_PKCS1_PSS_PADDING. The special value crypto.constants.RSA_PSS_SALTLEN_DIGEST sets the salt length to the digest size, crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN (default) sets it to the maximum permissible value.

If outputEncoding is provided a string is returned; otherwise a Buffer is returned.

The Sign object can not be again used after sign.sign() method has been called. Multiple calls to sign.sign() will result in an error being thrown.

sign.update(data[, inputEncoding])

• data <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the data string.

Updates the Sign content with the given data, the encoding of which is given in inputEncoding. If encoding is not provided, and the data is a string, an encoding of 'utf8' is enforced. If data is a Buffer, TypedArray, or DataView, then inputEncoding is ignored.

This can be called many times with new data as it is streamed.

Class: Verify

The Verify class is a utility for verifying signatures. It can be used in one of two ways:

• As a writable stream where written data is used to validate against the supplied signature, or
• Using the verify.update() and verify.verify() methods to verify the signature.

The crypto.createVerify() method is used to create Verify instances. Verify objects are not to be created directly using the new keyword.

Example: Using Verify objects as streams:

const crypto = require('crypto');
const verify = crypto.createVerify('SHA256');

verify.write('some data to sign');
verify.end();

const publicKey = getPublicKeySomehow();
const signature = getSignatureToVerify();
console.log(verify.verify(publicKey, signature));
// Prints: true or false

Example: Using the verify.update() and verify.verify() methods:

const crypto = require('crypto');
const verify = crypto.createVerify('SHA256');

verify.update('some data to sign');

const publicKey = getPublicKeySomehow();
const signature = getSignatureToVerify();
console.log(verify.verify(publicKey, signature));
// Prints: true or false

verify.update(data[, inputEncoding])

• data <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the data string.

Updates the Verify content with the given data, the encoding of which is given in inputEncoding. If inputEncoding is not provided, and the data is a string, an encoding of 'utf8' is enforced. If data is a Buffer, TypedArray, or DataView, then inputEncoding is ignored.

This can be called many times with new data as it is streamed.

verify.verify(object, signature[, signatureEncoding])

• object <string> | <Object>
• signature <string> | <Buffer> | <TypedArray> | <DataView>
• signatureEncoding <string> The encoding of the signature string.
• Returns: <boolean> true or false depending on the validity of the signature for the data and public key.

Verifies the provided data using the given object and signature. The object argument can be either a string containing a PEM encoded object, which can be an RSA public key, a DSA public key, or an X.509 certificate, or an object with one or more of the following properties:

• key: <string> - PEM encoded public key (required)

• padding: <integer> - Optional padding value for RSA, one of the following:

  • crypto.constants.RSA_PKCS1_PADDING (default)
  • crypto.constants.RSA_PKCS1_PSS_PADDING

  Note that RSA_PKCS1_PSS_PADDING will use MGF1 with the same hash function used to verify the message as specified in section 3.1 of RFC 4055.

• saltLength: <integer> - salt length for when padding is RSA_PKCS1_PSS_PADDING. The special value crypto.constants.RSA_PSS_SALTLEN_DIGEST sets the salt length to the digest size, crypto.constants.RSA_PSS_SALTLEN_AUTO (default) causes it to be determined automatically.

The signature argument is the previously calculated signature for the data, in the signatureEncoding. If a signatureEncoding is specified, the signature is expected to be a string; otherwise signature is expected to be a Buffer, TypedArray, or DataView.

The verify object can not be used again after verify.verify() has been called. Multiple calls to verify.verify() will result in an error being thrown.

crypto module methods and properties

crypto.constants

• Returns: <Object> An object containing commonly used constants for crypto and security related operations. The specific constants currently defined are described in Crypto Constants.

crypto.DEFAULT_ENCODING

The default encoding to use for functions that can take either strings or buffers. The default value is 'buffer', which makes methods default to Buffer objects.

The crypto.DEFAULT_ENCODING mechanism is provided for backwards compatibility with legacy programs that expect 'latin1' to be the default encoding.

New applications should expect the default to be 'buffer'.

This property is deprecated.

crypto.fips

Property for checking and controlling whether a FIPS compliant crypto provider is currently in use. Setting to true requires a FIPS build of Node.js.

This property is deprecated. Please use crypto.setFips() and crypto.getFips() instead.

crypto.createCipher(algorithm, password[, options])[src]

• algorithm <string>
• password <string> | <Buffer> | <TypedArray> | <DataView>
• options <Object> stream.transform options
• Returns: <Cipher>

Creates and returns a Cipher object that uses the given algorithm and password.

The options argument controls stream behavior and is optional except when a cipher in CCM or OCB mode is used (e.g. 'aes-128-ccm'). In that case, the authTagLength option is required and specifies the length of the authentication tag in bytes, see CCM mode. In GCM mode, the authTagLength option is not required but can be used to set the length of the authentication tag that will be returned by getAuthTag() and defaults to 16 bytes.

The algorithm is dependent on OpenSSL, examples are 'aes192', etc. On recent OpenSSL releases, openssl list -cipher-algorithms (openssl list-cipher-algorithms for older versions of OpenSSL) will display the available cipher algorithms.

The password is used to derive the cipher key and initialization vector (IV). The value must be either a 'latin1' encoded string, a Buffer, a TypedArray, or a DataView.

The implementation of crypto.createCipher() derives keys using the OpenSSL function EVP_BytesToKey with the digest algorithm set to MD5, one iteration, and no salt. The lack of salt allows dictionary attacks as the same password always creates the same key. The low iteration count and non-cryptographically secure hash algorithm allow passwords to be tested very rapidly.

In line with OpenSSL's recommendation to use a more modern algorithm instead of EVP_BytesToKey it is recommended that developers derive a key and IV on their own using crypto.scrypt() and to use crypto.createCipheriv() to create the Cipher object. Users should not use ciphers with counter mode (e.g. CTR, GCM, or CCM) in crypto.createCipher(). A warning is emitted when they are used in order to avoid the risk of IV reuse that causes vulnerabilities. For the case when IV is reused in GCM, see Nonce-Disrespecting Adversaries for details.

crypto.createCipheriv(algorithm, key, iv[, options])[src]

• algorithm <string>
• key <string> | <Buffer> | <TypedArray> | <DataView>
• iv <string> | <Buffer> | <TypedArray> | <DataView>
• options <Object> stream.transform options
• Returns: <Cipher>

Creates and returns a Cipher object, with the given algorithm, key and initialization vector (iv).

The options argument controls stream behavior and is optional except when a cipher in CCM or OCB mode is used (e.g. 'aes-128-ccm'). In that case, the authTagLength option is required and specifies the length of the authentication tag in bytes, see CCM mode. In GCM mode, the authTagLength option is not required but can be used to set the length of the authentication tag that will be returned by getAuthTag() and defaults to 16 bytes.

The algorithm is dependent on OpenSSL, examples are 'aes192', etc. On recent OpenSSL releases, openssl list -cipher-algorithms (openssl list-cipher-algorithms for older versions of OpenSSL) will display the available cipher algorithms.

The key is the raw key used by the algorithm and iv is an initialization vector. Both arguments must be 'utf8' encoded strings, Buffers, TypedArray, or DataViews. If the cipher does not need an initialization vector, iv may be null.

Initialization vectors should be unpredictable and unique; ideally, they will be cryptographically random. They do not have to be secret: IVs are typically just added to ciphertext messages unencrypted. It may sound contradictory that something has to be unpredictable and unique, but does not have to be secret; it is important to remember that an attacker must not be able to predict ahead of time what a given IV will be.

crypto.createCredentials(details)

• details <Object> Identical to tls.createSecureContext().
• Returns: <tls.SecureContext>

The crypto.createCredentials() method is a deprecated function for creating and returning a tls.SecureContext. It should not be used. Replace it with tls.createSecureContext() which has the exact same arguments and return value.

Returns a tls.SecureContext, as-if tls.createSecureContext() had been called.

crypto.createDecipher(algorithm, password[, options])[src]

• algorithm <string>
• password <string> | <Buffer> | <TypedArray> | <DataView>
• options <Object> stream.transform options
• Returns: <Decipher>

Creates and returns a Decipher object that uses the given algorithm and password (key).

The options argument controls stream behavior and is optional except when a cipher in CCM or OCB mode is used (e.g. 'aes-128-ccm'). In that case, the authTagLength option is required and specifies the length of the authentication tag in bytes, see CCM mode.

The implementation of crypto.createDecipher() derives keys using the OpenSSL function EVP_BytesToKey with the digest algorithm set to MD5, one iteration, and no salt. The lack of salt allows dictionary attacks as the same password always creates the same key. The low iteration count and non-cryptographically secure hash algorithm allow passwords to be tested very rapidly.

In line with OpenSSL's recommendation to use a more modern algorithm instead of EVP_BytesToKey it is recommended that developers derive a key and IV on their own using crypto.scrypt() and to use crypto.createDecipheriv() to create the Decipher object.

crypto.createDecipheriv(algorithm, key, iv[, options])[src]

• algorithm <string>
• key <string> | <Buffer> | <TypedArray> | <DataView>
• iv <string> | <Buffer> | <TypedArray> | <DataView>
• options <Object> stream.transform options
• Returns: <Decipher>

Creates and returns a Decipher object that uses the given algorithm, key and initialization vector (iv).

The options argument controls stream behavior and is optional except when a cipher in CCM or OCB mode is used (e.g. 'aes-128-ccm'). In that case, the authTagLength option is required and specifies the length of the authentication tag in bytes, see CCM mode. In GCM mode, the authTagLength option is not required but can be used to restrict accepted authentication tags to those with the specified length.

The algorithm is dependent on OpenSSL, examples are 'aes192', etc. On recent OpenSSL releases, openssl list -cipher-algorithms (openssl list-cipher-algorithms for older versions of OpenSSL) will display the available cipher algorithms.

The key is the raw key used by the algorithm and iv is an initialization vector. Both arguments must be 'utf8' encoded strings, Buffers, TypedArray, or DataViews. If the cipher does not need an initialization vector, iv may be null.

Initialization vectors should be unpredictable and unique; ideally, they will be cryptographically random. They do not have to be secret: IVs are typically just added to ciphertext messages unencrypted. It may sound contradictory that something has to be unpredictable and unique, but does not have to be secret; it is important to remember that an attacker must not be able to predict ahead of time what a given IV will be.

crypto.createDiffieHellman(prime[, primeEncoding][, generator][, generatorEncoding])[src]

• prime <string> | <Buffer> | <TypedArray> | <DataView>
• primeEncoding <string> The encoding of the prime string.
• generator <number> | <string> | <Buffer> | <TypedArray> | <DataView> Default: 2
• generatorEncoding <string> The encoding of the generator string.
• Returns: <DiffieHellman>

Creates a DiffieHellman key exchange object using the supplied prime and an optional specific generator.

The generator argument can be a number, string, or Buffer. If generator is not specified, the value 2 is used.

If primeEncoding is specified, prime is expected to be a string; otherwise a Buffer, TypedArray, or DataView is expected.

If generatorEncoding is specified, generator is expected to be a string; otherwise a number, Buffer, TypedArray, or DataView is expected.

crypto.createDiffieHellman(primeLength[, generator])[src]

• primeLength <number>
• generator <number> | <string> | <Buffer> | <TypedArray> | <DataView> Default: 2
• Returns: <DiffieHellman>

Creates a DiffieHellman key exchange object and generates a prime of primeLength bits using an optional specific numeric generator. If generator is not specified, the value 2 is used.

crypto.createECDH(curveName)[src]

• curveName <string>
• Returns: <ECDH>

Creates an Elliptic Curve Diffie-Hellman (ECDH) key exchange object using a predefined curve specified by the curveName string. Use crypto.getCurves() to obtain a list of available curve names. On recent OpenSSL releases, openssl ecparam -list_curves will also display the name and description of each available elliptic curve.

crypto.createHash(algorithm[, options])[src]

• algorithm <string>
• options <Object> stream.transform options
• Returns: <Hash>

Creates and returns a Hash object that can be used to generate hash digests using the given algorithm. Optional options argument controls stream behavior.

The algorithm is dependent on the available algorithms supported by the version of OpenSSL on the platform. Examples are 'sha256', 'sha512', etc. On recent releases of OpenSSL, openssl list -digest-algorithms (openssl list-message-digest-algorithms for older versions of OpenSSL) will display the available digest algorithms.

Example: generating the sha256 sum of a file

const filename = process.argv[2];
const crypto = require('crypto');
const fs = require('fs');

const hash = crypto.createHash('sha256');

const input = fs.createReadStream(filename);
input.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = input.read();
  if (data)
    hash.update(data);
  else {
    console.log(`${hash.digest('hex')} ${filename}`);
  }
});

crypto.createHmac(algorithm, key[, options])[src]

• algorithm <string>
• key <string> | <Buffer> | <TypedArray> | <DataView>
• options <Object> stream.transform options
• Returns: <Hmac>

Creates and returns an Hmac object that uses the given algorithm and key. Optional options argument controls stream behavior.

The algorithm is dependent on the available algorithms supported by the version of OpenSSL on the platform. Examples are 'sha256', 'sha512', etc. On recent releases of OpenSSL, openssl list -digest-algorithms (openssl list-message-digest-algorithms for older versions of OpenSSL) will display the available digest algorithms.

The key is the HMAC key used to generate the cryptographic HMAC hash.

Example: generating the sha256 HMAC of a file

const filename = process.argv[2];
const crypto = require('crypto');
const fs = require('fs');

const hmac = crypto.createHmac('sha256', 'a secret');

const input = fs.createReadStream(filename);
input.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = input.read();
  if (data)
    hmac.update(data);
  else {
    console.log(`${hmac.digest('hex')} ${filename}`);
  }
});

crypto.createSign(algorithm[, options])[src]

• algorithm <string>
• options <Object> stream.Writable options
• Returns: <Sign>

Creates and returns a Sign object that uses the given algorithm. Use crypto.getHashes() to obtain an array of names of the available signing algorithms. Optional options argument controls the stream.Writable behavior.

crypto.createVerify(algorithm[, options])[src]

• algorithm <string>
• options <Object> stream.Writable options
• Returns: <Verify>

Creates and returns a Verify object that uses the given algorithm. Use crypto.getHashes() to obtain an array of names of the available signing algorithms. Optional options argument controls the stream.Writable behavior.

crypto.generateKeyPair(type, options, callback)

• type: <string> Must be 'rsa', 'dsa' or 'ec'.

• options: <Object>

  • modulusLength: <number> Key size in bits (RSA, DSA).
  • publicExponent: <number> Public exponent (RSA). Default: 0x10001.
  • divisorLength: <number> Size of q in bits (DSA).
  • namedCurve: <string> Name of the curve to use (EC).

  • publicKeyEncoding: <Object>

    • type: <string> Must be one of 'pkcs1' (RSA only) or 'spki'.
    • format: <string> Must be 'pem' or 'der'.

  • privateKeyEncoding: <Object>

    • type: <string> Must be one of 'pkcs1' (RSA only), 'pkcs8' or 'sec1' (EC only).
    • format: <string> Must be 'pem' or 'der'.
    • cipher: <string> If specified, the private key will be encrypted with the given cipher and passphrase using PKCS#5 v2.0 password based encryption.
    • passphrase: <string> The passphrase to use for encryption, see cipher.

• callback: <Function>

  • err: <Error>
  • publicKey: <string> | <Buffer>
  • privateKey: <string> | <Buffer>

Generates a new asymmetric key pair of the given type. Only RSA, DSA and EC are currently supported.

It is recommended to encode public keys as 'spki' and private keys as 'pkcs8' with encryption:

const { generateKeyPair } = require('crypto');
generateKeyPair('rsa', {
  modulusLength: 4096,
  publicKeyEncoding: {
    type: 'spki',
    format: 'pem'
  },
  privateKeyEncoding: {
    type: 'pkcs8',
    format: 'pem',
    cipher: 'aes-256-cbc',
    passphrase: 'top secret'
  }
}, (err, publicKey, privateKey) => {
  // Handle errors and use the generated key pair.
});

On completion, callback will be called with err set to undefined and publicKey / privateKey representing the generated key pair. When PEM encoding was selected, the result will be a string, otherwise it will be a buffer containing the data encoded as DER. Note that Node.js itself does not accept DER, it is supported for interoperability with other libraries such as WebCrypto only.

If this method is invoked as its util.promisify()ed version, it returns a Promise for an Object with publicKey and privateKey properties.

crypto.generateKeyPairSync(type, options)

• type: <string> Must be 'rsa', 'dsa' or 'ec'.

• options: <Object>

  • modulusLength: <number> Key size in bits (RSA, DSA).
  • publicExponent: <number> Public exponent (RSA). Default: 0x10001.
  • divisorLength: <number> Size of q in bits (DSA).
  • namedCurve: <string> Name of the curve to use (EC).

  • publicKeyEncoding: <Object>

    • type: <string> Must be one of 'pkcs1' (RSA only) or 'spki'.
    • format: <string> Must be 'pem' or 'der'.

  • privateKeyEncoding: <Object>

    • type: <string> Must be one of 'pkcs1' (RSA only), 'pkcs8' or 'sec1' (EC only).
    • format: <string> Must be 'pem' or 'der'.
    • cipher: <string> If specified, the private key will be encrypted with the given cipher and passphrase using PKCS#5 v2.0 password based encryption.
    • passphrase: <string> The passphrase to use for encryption, see cipher.

• Returns: <Object>

  • publicKey: <string> | <Buffer>
  • privateKey: <string> | <Buffer>

Generates a new asymmetric key pair of the given type. Only RSA, DSA and EC are currently supported.

It is recommended to encode public keys as 'spki' and private keys as 'pkcs8' with encryption:

const { generateKeyPairSync } = require('crypto');
const { publicKey, privateKey } = generateKeyPairSync('rsa', {
  modulusLength: 4096,
  publicKeyEncoding: {
    type: 'spki',
    format: 'pem'
  },
  privateKeyEncoding: {
    type: 'pkcs8',
    format: 'pem',
    cipher: 'aes-256-cbc',
    passphrase: 'top secret'
  }
});

The return value { publicKey, privateKey } represents the generated key pair. When PEM encoding was selected, the respective key will be a string, otherwise it will be a buffer containing the data encoded as DER.

crypto.getCiphers()

• Returns: <string[]> An array with the names of the supported cipher algorithms.

const ciphers = crypto.getCiphers();
console.log(ciphers); // ['aes-128-cbc', 'aes-128-ccm', ...]

crypto.getCurves()

• Returns: <string[]> An array with the names of the supported elliptic curves.

const curves = crypto.getCurves();
console.log(curves); // ['Oakley-EC2N-3', 'Oakley-EC2N-4', ...]

crypto.getDiffieHellman(groupName)

• groupName <string>
• Returns: <DiffieHellman>

Creates a predefined DiffieHellman key exchange object. The supported groups are: 'modp1', 'modp2', 'modp5' (defined in RFC 2412, but see Caveats) and 'modp14', 'modp15', 'modp16', 'modp17', 'modp18' (defined in RFC 3526). The returned object mimics the interface of objects created by crypto.createDiffieHellman(), but will not allow changing the keys (with diffieHellman.setPublicKey(), for example). The advantage of using this method is that the parties do not have to generate nor exchange a group modulus beforehand, saving both processor and communication time.

Example (obtaining a shared secret):

const crypto = require('crypto');
const alice = crypto.getDiffieHellman('modp14');
const bob = crypto.getDiffieHellman('modp14');

alice.generateKeys();
bob.generateKeys();

const aliceSecret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
const bobSecret = bob.computeSecret(alice.getPublicKey(), null, 'hex');

/* aliceSecret and bobSecret should be the same */
console.log(aliceSecret === bobSecret);

crypto.getFips()

• Returns: <boolean> true if and only if a FIPS compliant crypto provider is currently in use.

crypto.getHashes()

• Returns: <string[]> An array of the names of the supported hash algorithms, such as 'RSA-SHA256'.

const hashes = crypto.getHashes();
console.log(hashes); // ['DSA', 'DSA-SHA', 'DSA-SHA1', ...]

crypto.pbkdf2(password, salt, iterations, keylen, digest, callback)

• password <string> | <Buffer> | <TypedArray> | <DataView>
• salt <string> | <Buffer> | <TypedArray> | <DataView>
• iterations <number>
• keylen <number>
• digest <string>

• callback <Function>

  • err <Error>
  • derivedKey <Buffer>

Provides an asynchronous Password-Based Key Derivation Function 2 (PBKDF2) implementation. A selected HMAC digest algorithm specified by digest is applied to derive a key of the requested byte length (keylen) from the password, salt and iterations.

The supplied callback function is called with two arguments: err and derivedKey. If an error occurs while deriving the key, err will be set; otherwise err will be null. By default, the successfully generated derivedKey will be passed to the callback as a Buffer. An error will be thrown if any of the input arguments specify invalid values or types.

If digest is null, 'sha1' will be used. This behavior will be deprecated in a future version of Node.js.

The iterations argument must be a number set as high as possible. The higher the number of iterations, the more secure the derived key will be, but will take a longer amount of time to complete.

The salt should be as unique as possible. It is recommended that a salt is random and at least 16 bytes long. See NIST SP 800-132 for details.

const crypto = require('crypto');
crypto.pbkdf2('secret', 'salt', 100000, 64, 'sha512', (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));  // '3745e48...08d59ae'
});

The crypto.DEFAULT_ENCODING property can be used to change the way the derivedKey is passed to the callback. This property, however, has been deprecated and use should be avoided.

const crypto = require('crypto');
crypto.DEFAULT_ENCODING = 'hex';
crypto.pbkdf2('secret', 'salt', 100000, 512, 'sha512', (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey);  // '3745e48...aa39b34'
});

An array of supported digest functions can be retrieved using crypto.getHashes().

Note that this API uses libuv's threadpool, which can have surprising and negative performance implications for some applications, see the UV_THREADPOOL_SIZE documentation for more information.

crypto.pbkdf2Sync(password, salt, iterations, keylen, digest)

• password <string> | <Buffer> | <TypedArray> | <DataView>
• salt <string> | <Buffer> | <TypedArray> | <DataView>
• iterations <number>
• keylen <number>
• digest <string>
• Returns: <Buffer>

Provides a synchronous Password-Based Key Derivation Function 2 (PBKDF2) implementation. A selected HMAC digest algorithm specified by digest is applied to derive a key of the requested byte length (keylen) from the password, salt and iterations.

If an error occurs an Error will be thrown, otherwise the derived key will be returned as a Buffer.

If digest is null, 'sha1' will be used. This behavior will be deprecated in a future version of Node.js.

The iterations argument must be a number set as high as possible. The higher the number of iterations, the more secure the derived key will be, but will take a longer amount of time to complete.

The salt should be as unique as possible. It is recommended that a salt is random and at least 16 bytes long. See NIST SP 800-132 for details.

const crypto = require('crypto');
const key = crypto.pbkdf2Sync('secret', 'salt', 100000, 64, 'sha512');
console.log(key.toString('hex'));  // '3745e48...08d59ae'

The crypto.DEFAULT_ENCODING property may be used to change the way the derivedKey is returned. This property, however, is deprecated and use should be avoided.

const crypto = require('crypto');
crypto.DEFAULT_ENCODING = 'hex';
const key = crypto.pbkdf2Sync('secret', 'salt', 100000, 512, 'sha512');
console.log(key);  // '3745e48...aa39b34'

An array of supported digest functions can be retrieved using crypto.getHashes().

crypto.privateDecrypt(privateKey, buffer)

• privateKey <Object> | <string>

  • key <string> A PEM encoded private key.
  • passphrase <string> An optional passphrase for the private key.
  • padding <crypto.constants> An optional padding value defined in crypto.constants, which may be: crypto.constants.RSA_NO_PADDING, crypto.constants.RSA_PKCS1_PADDING, or crypto.constants.RSA_PKCS1_OAEP_PADDING.
• buffer <Buffer> | <TypedArray> | <DataView>
• Returns: <Buffer> A new Buffer with the decrypted content.

Decrypts buffer with privateKey. buffer was previously encrypted using the corresponding public key, for example using crypto.publicEncrypt().

privateKey can be an object or a string. If privateKey is a string, it is treated as the key with no passphrase and will use RSA_PKCS1_OAEP_PADDING.

crypto.privateEncrypt(privateKey, buffer)

• privateKey <Object> | <string>

  • key <string> A PEM encoded private key.
  • passphrase <string> An optional passphrase for the private key.
  • padding <crypto.constants> An optional padding value defined in crypto.constants, which may be: crypto.constants.RSA_NO_PADDING or crypto.constants.RSA_PKCS1_PADDING.
• buffer <Buffer> | <TypedArray> | <DataView>
• Returns: <Buffer> A new Buffer with the encrypted content.

Encrypts buffer with privateKey. The returned data can be decrypted using the corresponding public key, for example using crypto.publicDecrypt().

privateKey can be an object or a string. If privateKey is a string, it is treated as the key with no passphrase and will use RSA_PKCS1_PADDING.

crypto.publicDecrypt(key, buffer)

• key <Object> | <string>

  • key <string> A PEM encoded public or private key.
  • passphrase <string> An optional passphrase for the private key.
  • padding <crypto.constants> An optional padding value defined in crypto.constants, which may be: crypto.constants.RSA_NO_PADDING or crypto.constants.RSA_PKCS1_PADDING.
• buffer <Buffer> | <TypedArray> | <DataView>
• Returns: <Buffer> A new Buffer with the decrypted content.

Decrypts buffer with key.buffer was previously encrypted using the corresponding private key, for example using crypto.privateEncrypt().

key can be an object or a string. If key is a string, it is treated as the key with no passphrase and will use RSA_PKCS1_PADDING.

Because RSA public keys can be derived from private keys, a private key may be passed instead of a public key.

crypto.publicEncrypt(key, buffer)

• key <Object> | <string>

  • key <string> A PEM encoded public or private key.
  • passphrase <string> An optional passphrase for the private key.
  • padding <crypto.constants> An optional padding value defined in crypto.constants, which may be: crypto.constants.RSA_NO_PADDING, crypto.constants.RSA_PKCS1_PADDING, or crypto.constants.RSA_PKCS1_OAEP_PADDING.
• buffer <Buffer> | <TypedArray> | <DataView>
• Returns: <Buffer> A new Buffer with the encrypted content.

Encrypts the content of buffer with key and returns a new Buffer with encrypted content. The returned data can be decrypted using the corresponding private key, for example using crypto.privateDecrypt().

key can be an object or a string. If key is a string, it is treated as the key with no passphrase and will use RSA_PKCS1_OAEP_PADDING.

Because RSA public keys can be derived from private keys, a private key may be passed instead of a public key.

crypto.randomBytes(size[, callback])

• size <number>

• callback <Function>

  • err <Error>
  • buf <Buffer>
• Returns: <Buffer> if the callback function is not provided.

Generates cryptographically strong pseudo-random data. The size argument is a number indicating the number of bytes to generate.

If a callback function is provided, the bytes are generated asynchronously and the callback function is invoked with two arguments: err and buf. If an error occurs, err will be an Error object; otherwise it is null. The buf argument is a Buffer containing the generated bytes.

// Asynchronous
const crypto = require('crypto');
crypto.randomBytes(256, (err, buf) => {
  if (err) throw err;
  console.log(`${buf.length} bytes of random data: ${buf.toString('hex')}`);
});

If the callback function is not provided, the random bytes are generated synchronously and returned as a Buffer. An error will be thrown if there is a problem generating the bytes.

// Synchronous
const buf = crypto.randomBytes(256);
console.log(
  `${buf.length} bytes of random data: ${buf.toString('hex')}`);

The crypto.randomBytes() method will not complete until there is sufficient entropy available. This should normally never take longer than a few milliseconds. The only time when generating the random bytes may conceivably block for a longer period of time is right after boot, when the whole system is still low on entropy.

Note that this API uses libuv's threadpool, which can have surprising and negative performance implications for some applications, see the UV_THREADPOOL_SIZE documentation for more information.

The asynchronous version of crypto.randomBytes() is carried out in a single threadpool request. To minimize threadpool task length variation, partition large randomBytes requests when doing so as part of fulfilling a client request.

crypto.randomFillSync(buffer[, offset][, size])

• buffer <Buffer> | <TypedArray> | <DataView> Must be supplied.
• offset <number> Default: 0
• size <number> Default: buffer.length - offset
• Returns: <Buffer> | <TypedArray> | <DataView> The object passed as buffer argument.

Synchronous version of crypto.randomFill().

const buf = Buffer.alloc(10);
console.log(crypto.randomFillSync(buf).toString('hex'));

crypto.randomFillSync(buf, 5);
console.log(buf.toString('hex'));

// The above is equivalent to the following:
crypto.randomFillSync(buf, 5, 5);
console.log(buf.toString('hex'));

Any TypedArray or DataView instance may be passed as buffer.

const a = new Uint32Array(10);
console.log(Buffer.from(crypto.randomFillSync(a).buffer,
                        a.byteOffset, a.byteLength).toString('hex'));

const b = new Float64Array(10);
console.log(Buffer.from(crypto.randomFillSync(b).buffer,
                        b.byteOffset, b.byteLength).toString('hex'));

const c = new DataView(new ArrayBuffer(10));
console.log(Buffer.from(crypto.randomFillSync(c).buffer,
                        c.byteOffset, c.byteLength).toString('hex'));

crypto.randomFill(buffer[, offset][, size], callback)

• buffer <Buffer> | <TypedArray> | <DataView> Must be supplied.
• offset <number> Default: 0
• size <number> Default: buffer.length - offset
• callback <Function> function(err, buf) {}.

This function is similar to crypto.randomBytes() but requires the first argument to be a Buffer that will be filled. It also requires that a callback is passed in.

If the callback function is not provided, an error will be thrown.

const buf = Buffer.alloc(10);
crypto.randomFill(buf, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

crypto.randomFill(buf, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

// The above is equivalent to the following:
crypto.randomFill(buf, 5, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

Any TypedArray or DataView instance may be passed as buffer.

const a = new Uint32Array(10);
crypto.randomFill(a, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const b = new Float64Array(10);
crypto.randomFill(b, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const c = new DataView(new ArrayBuffer(10));
crypto.randomFill(c, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

Note that this API uses libuv's threadpool, which can have surprising and negative performance implications for some applications, see the UV_THREADPOOL_SIZE documentation for more information.

The asynchronous version of crypto.randomFill() is carried out in a single threadpool request. To minimize threadpool task length variation, partition large randomFill requests when doing so as part of fulfilling a client request.

crypto.scrypt(password, salt, keylen[, options], callback)

• password <string> | <Buffer> | <TypedArray> | <DataView>
• salt <string> | <Buffer> | <TypedArray> | <DataView>
• keylen <number>

• options <Object>

  • cost <number> CPU/memory cost parameter. Must be a power of two greater
  • N <number> CPU/memory cost parameter. Must be a power of two greater than one. Default: 16384.
  • blockSize <number> Block size parameter. Default: 8.
  • parallelization <number> Parallelization parameter. Default: 1.
  • N <number> Alias for cost. Only one of both may be specified.
  • r <number> Alias for blockSize. Only one of both may be specified.
  • p <number> Alias for parallelization. Only one of both may be specified.
  • maxmem <number> Memory upper bound. It is an error when (approximately) 128 * N * r > maxmem. Default: 32 * 1024 * 1024.

• callback <Function>

  • err <Error>
  • derivedKey <Buffer>

Provides an asynchronous scrypt implementation. Scrypt is a password-based key derivation function that is designed to be expensive computationally and memory-wise in order to make brute-force attacks unrewarding.

The salt should be as unique as possible. It is recommended that a salt is random and at least 16 bytes long. See NIST SP 800-132 for details.

The callback function is called with two arguments: err and derivedKey. err is an exception object when key derivation fails, otherwise err is null. derivedKey is passed to the callback as a Buffer.

An exception is thrown when any of the input arguments specify invalid values or types.

const crypto = require('crypto');
// Using the factory defaults.
crypto.scrypt('secret', 'salt', 64, (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));  // '3745e48...08d59ae'
});
// Using a custom N parameter. Must be a power of two.
crypto.scrypt('secret', 'salt', 64, { N: 1024 }, (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));  // '3745e48...aa39b34'
});

crypto.scryptSync(password, salt, keylen[, options])

• password <string> | <Buffer> | <TypedArray> | <DataView>
• salt <string> | <Buffer> | <TypedArray> | <DataView>
• keylen <number>

• options <Object>

  • cost <number> CPU/memory cost parameter. Must be a power of two greater
  • N <number> CPU/memory cost parameter. Must be a power of two greater than one. Default: 16384.
  • blockSize <number> Block size parameter. Default: 8.
  • parallelization <number> Parallelization parameter. Default: 1.
  • N <number> Alias for cost. Only one of both may be specified.
  • r <number> Alias for blockSize. Only one of both may be specified.
  • p <number> Alias for parallelization. Only one of both may be specified.
  • maxmem <number> Memory upper bound. It is an error when (approximately) 128 * N * r > maxmem. Default: 32 * 1024 * 1024.
• Returns: <Buffer>

Provides a synchronous scrypt implementation. Scrypt is a password-based key derivation function that is designed to be expensive computationally and memory-wise in order to make brute-force attacks unrewarding.

The salt should be as unique as possible. It is recommended that a salt is random and at least 16 bytes long. See NIST SP 800-132 for details.

An exception is thrown when key derivation fails, otherwise the derived key is returned as a Buffer.

An exception is thrown when any of the input arguments specify invalid values or types.

const crypto = require('crypto');
// Using the factory defaults.
const key1 = crypto.scryptSync('secret', 'salt', 64);
console.log(key1.toString('hex'));  // '3745e48...08d59ae'
// Using a custom N parameter. Must be a power of two.
const key2 = crypto.scryptSync('secret', 'salt', 64, { N: 1024 });
console.log(key2.toString('hex'));  // '3745e48...aa39b34'

crypto.setEngine(engine[, flags])

• engine <string>
• flags <crypto.constants> Default: crypto.constants.ENGINE_METHOD_ALL

Load and set the engine for some or all OpenSSL functions (selected by flags).

engine could be either an id or a path to the engine's shared library.

The optional flags argument uses ENGINE_METHOD_ALL by default. The flags is a bit field taking one of or a mix of the following flags (defined in crypto.constants):

• crypto.constants.ENGINE_METHOD_RSA
• crypto.constants.ENGINE_METHOD_DSA
• crypto.constants.ENGINE_METHOD_DH
• crypto.constants.ENGINE_METHOD_RAND
• crypto.constants.ENGINE_METHOD_EC
• crypto.constants.ENGINE_METHOD_CIPHERS
• crypto.constants.ENGINE_METHOD_DIGESTS
• crypto.constants.ENGINE_METHOD_PKEY_METHS
• crypto.constants.ENGINE_METHOD_PKEY_ASN1_METHS
• crypto.constants.ENGINE_METHOD_ALL
• crypto.constants.ENGINE_METHOD_NONE

The flags below are deprecated in OpenSSL-1.1.0.

• crypto.constants.ENGINE_METHOD_ECDH
• crypto.constants.ENGINE_METHOD_ECDSA
• crypto.constants.ENGINE_METHOD_STORE

crypto.setFips(bool)

• bool <boolean> true to enable FIPS mode.

Enables the FIPS compliant crypto provider in a FIPS-enabled Node.js build. Throws an error if FIPS mode is not available.

crypto.timingSafeEqual(a, b)

• a <Buffer> | <TypedArray> | <DataView>
• b <Buffer> | <TypedArray> | <DataView>
• Returns: <boolean>

This function is based on a constant-time algorithm. Returns true if a is equal to b, without leaking timing information that would allow an attacker to guess one of the values. This is suitable for comparing HMAC digests or secret values like authentication cookies or capability urls.

a and b must both be Buffers, TypedArrays, or DataViews, and they must have the same length.

Use of crypto.timingSafeEqual does not guarantee that the surrounding code is timing-safe. Care should be taken to ensure that the surrounding code does not introduce timing vulnerabilities.

Notes

Legacy Streams API (pre Node.js v0.10)

The Crypto module was added to Node.js before there was the concept of a unified Stream API, and before there were Buffer objects for handling binary data. As such, the many of the crypto defined classes have methods not typically found on other Node.js classes that implement the streams API (e.g. update(), final(), or digest()). Also, many methods accepted and returned 'latin1' encoded strings by default rather than Buffers. This default was changed after Node.js v0.8 to use Buffer objects by default instead.

Recent ECDH Changes

Usage of ECDH with non-dynamically generated key pairs has been simplified. Now, ecdh.setPrivateKey() can be called with a preselected private key and the associated public point (key) will be computed and stored in the object. This allows code to only store and provide the private part of the EC key pair. ecdh.setPrivateKey() now also validates that the private key is valid for the selected curve.

The ecdh.setPublicKey() method is now deprecated as its inclusion in the API is not useful. Either a previously stored private key should be set, which automatically generates the associated public key, or ecdh.generateKeys() should be called. The main drawback of using ecdh.setPublicKey() is that it can be used to put the ECDH key pair into an inconsistent state.

Support for weak or compromised algorithms

The crypto module still supports some algorithms which are already compromised and are not currently recommended for use. The API also allows the use of ciphers and hashes with a small key size that are considered to be too weak for safe use.

Users should take full responsibility for selecting the crypto algorithm and key size according to their security requirements.

Based on the recommendations of NIST SP 800-131A:

• MD5 and SHA-1 are no longer acceptable where collision resistance is required such as digital signatures.
• The key used with RSA, DSA, and DH algorithms is recommended to have at least 2048 bits and that of the curve of ECDSA and ECDH at least 224 bits, to be safe to use for several years.
• The DH groups of modp1, modp2 and modp5 have a key size smaller than 2048 bits and are not recommended.

See the reference for other recommendations and details.

CCM mode

CCM is one of the supported AEAD algorithms. Applications which use this mode must adhere to certain restrictions when using the cipher API:

• The authentication tag length must be specified during cipher creation by setting the authTagLength option and must be one of 4, 6, 8, 10, 12, 14 or 16 bytes.
• The length of the initialization vector (nonce) N must be between 7 and 13 bytes (7 ≤ N ≤ 13).
• The length of the plaintext is limited to 2 ** (8 * (15 - N)) bytes.
• When decrypting, the authentication tag must be set via setAuthTag() before specifying additional authenticated data or calling update(). Otherwise, decryption will fail and final() will throw an error in compliance with section 2.6 of RFC 3610.
• Using stream methods such as write(data), end(data) or pipe() in CCM mode might fail as CCM cannot handle more than one chunk of data per instance.
• When passing additional authenticated data (AAD), the length of the actual message in bytes must be passed to setAAD() via the plaintextLength option. This is not necessary if no AAD is used.
• As CCM processes the whole message at once, update() can only be called once.
• Even though calling update() is sufficient to encrypt/decrypt the message, applications must call final() to compute or verify the authentication tag.

const crypto = require('crypto');

const key = 'keykeykeykeykeykeykeykey';
const nonce = crypto.randomBytes(12);

const aad = Buffer.from('0123456789', 'hex');

const cipher = crypto.createCipheriv('aes-192-ccm', key, nonce, {
  authTagLength: 16
});
const plaintext = 'Hello world';
cipher.setAAD(aad, {
  plaintextLength: Buffer.byteLength(plaintext)
});
const ciphertext = cipher.update(plaintext, 'utf8');
cipher.final();
const tag = cipher.getAuthTag();

// Now transmit { ciphertext, nonce, tag }.

const decipher = crypto.createDecipheriv('aes-192-ccm', key, nonce, {
  authTagLength: 16
});
decipher.setAuthTag(tag);
decipher.setAAD(aad, {
  plaintextLength: ciphertext.length
});
const receivedPlaintext = decipher.update(ciphertext, null, 'utf8');

try {
  decipher.final();
} catch (err) {
  console.error('Authentication failed!');
}

console.log(receivedPlaintext);

Crypto Constants

The following constants exported by crypto.constants apply to various uses of the crypto, tls, and https modules and are generally specific to OpenSSL.

OpenSSL Options

Constant	Description
SSL_OP_ALL	Applies multiple bug workarounds within OpenSSL. See https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html for detail.
SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION	Allows legacy insecure renegotiation between OpenSSL and unpatched clients or servers. See https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html.
SSL_OP_CIPHER_SERVER_PREFERENCE	Attempts to use the server's preferences instead of the client's when selecting a cipher. Behavior depends on protocol version. See https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html.
SSL_OP_CISCO_ANYCONNECT	Instructs OpenSSL to use Cisco's "speshul" version of DTLS_BAD_VER.
SSL_OP_COOKIE_EXCHANGE	Instructs OpenSSL to turn on cookie exchange.
SSL_OP_CRYPTOPRO_TLSEXT_BUG	Instructs OpenSSL to add server-hello extension from an early version of the cryptopro draft.
SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS	Instructs OpenSSL to disable a SSL 3.0/TLS 1.0 vulnerability workaround added in OpenSSL 0.9.6d.
SSL_OP_EPHEMERAL_RSA	Instructs OpenSSL to always use the tmp_rsa key when performing RSA operations.
SSL_OP_LEGACY_SERVER_CONNECT	Allows initial connection to servers that do not support RI.
SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
SSL_OP_MICROSOFT_SESS_ID_BUG
SSL_OP_MSIE_SSLV2_RSA_PADDING	Instructs OpenSSL to disable the workaround for a man-in-the-middle protocol-version vulnerability in the SSL 2.0 server implementation.
SSL_OP_NETSCAPE_CA_DN_BUG
SSL_OP_NETSCAPE_CHALLENGE_BUG
SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG
SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
SSL_OP_NO_COMPRESSION	Instructs OpenSSL to disable support for SSL/TLS compression.
SSL_OP_NO_QUERY_MTU
SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION	Instructs OpenSSL to always start a new session when performing renegotiation.
SSL_OP_NO_SSLv2	Instructs OpenSSL to turn off SSL v2
SSL_OP_NO_SSLv3	Instructs OpenSSL to turn off SSL v3
SSL_OP_NO_TICKET	Instructs OpenSSL to disable use of RFC4507bis tickets.
SSL_OP_NO_TLSv1	Instructs OpenSSL to turn off TLS v1
SSL_OP_NO_TLSv1_1	Instructs OpenSSL to turn off TLS v1.1
SSL_OP_NO_TLSv1_2	Instructs OpenSSL to turn off TLS v1.2
SSL_OP_PKCS1_CHECK_1
SSL_OP_PKCS1_CHECK_2
SSL_OP_SINGLE_DH_USE	Instructs OpenSSL to always create a new key when using temporary/ephemeral DH parameters.
SSL_OP_SINGLE_ECDH_USE	Instructs OpenSSL to always create a new key when using temporary/ephemeral ECDH parameters.
SSL_OP_SSLEAY_080_CLIENT_DH_BUG
SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
SSL_OP_TLS_BLOCK_PADDING_BUG
SSL_OP_TLS_D5_BUG
SSL_OP_TLS_ROLLBACK_BUG	Instructs OpenSSL to disable version rollback attack detection.

OpenSSL Engine Constants

Constant	Description
ENGINE_METHOD_RSA	Limit engine usage to RSA
ENGINE_METHOD_DSA	Limit engine usage to DSA
ENGINE_METHOD_DH	Limit engine usage to DH
ENGINE_METHOD_RAND	Limit engine usage to RAND
ENGINE_METHOD_EC	Limit engine usage to EC
ENGINE_METHOD_CIPHERS	Limit engine usage to CIPHERS
ENGINE_METHOD_DIGESTS	Limit engine usage to DIGESTS
ENGINE_METHOD_PKEY_METHS	Limit engine usage to PKEY_METHDS
ENGINE_METHOD_PKEY_ASN1_METHS	Limit engine usage to PKEY_ASN1_METHS
ENGINE_METHOD_ALL
ENGINE_METHOD_NONE

Other OpenSSL Constants

Constant	Description
DH_CHECK_P_NOT_SAFE_PRIME
DH_CHECK_P_NOT_PRIME
DH_UNABLE_TO_CHECK_GENERATOR
DH_NOT_SUITABLE_GENERATOR
ALPN_ENABLED
RSA_PKCS1_PADDING
RSA_SSLV23_PADDING
RSA_NO_PADDING
RSA_PKCS1_OAEP_PADDING
RSA_X931_PADDING
RSA_PKCS1_PSS_PADDING
RSA_PSS_SALTLEN_DIGEST	Sets the salt length for RSA_PKCS1_PSS_PADDING to the digest size when signing or verifying.
RSA_PSS_SALTLEN_MAX_SIGN	Sets the salt length for RSA_PKCS1_PSS_PADDING to the maximum permissible value when signing data.
RSA_PSS_SALTLEN_AUTO	Causes the salt length for RSA_PKCS1_PSS_PADDING to be determined automatically when verifying a signature.
POINT_CONVERSION_COMPRESSED
POINT_CONVERSION_UNCOMPRESSED
POINT_CONVERSION_HYBRID

Node.js Crypto Constants

Constant	Description
defaultCoreCipherList	Specifies the built-in default cipher list used by Node.js.
defaultCipherList	Specifies the active default cipher list used by the current Node.js process.