3 Stability: 2 - Unstable; API changes are being discussed for
4 future versions. Breaking changes will be minimized. See below.
6 Use `require('crypto')` to access this module.
8 The crypto module offers a way of encapsulating secure credentials to be
9 used as part of a secure HTTPS net or http connection.
11 It also offers a set of wrappers for OpenSSL's hash, hmac, cipher,
12 decipher, sign and verify methods.
15 ## crypto.getCiphers()
17 Returns an array with the names of the supported ciphers.
21 var ciphers = crypto.getCiphers();
22 console.log(ciphers); // ['AES-128-CBC', 'AES-128-CBC-HMAC-SHA1', ...]
27 Returns an array with the names of the supported hash algorithms.
31 var hashes = crypto.getHashes();
32 console.log(hashes); // ['sha', 'sha1', 'sha1WithRSAEncryption', ...]
35 ## crypto.createCredentials(details)
37 Creates a credentials object, with the optional details being a
40 * `pfx` : A string or buffer holding the PFX or PKCS12 encoded private
41 key, certificate and CA certificates
42 * `key` : A string holding the PEM encoded private key
43 * `passphrase` : A string of passphrase for the private key or pfx
44 * `cert` : A string holding the PEM encoded certificate
45 * `ca` : Either a string or list of strings of PEM encoded CA
46 certificates to trust.
47 * `crl` : Either a string or list of strings of PEM encoded CRLs
48 (Certificate Revocation List)
49 * `ciphers`: A string describing the ciphers to use or exclude.
51 <http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT>
52 for details on the format.
54 If no 'ca' details are given, then node.js will use the default
55 publicly trusted list of CAs as given in
56 <http://mxr.mozilla.org/mozilla/source/security/nss/lib/ckfw/builtins/certdata.txt>.
59 ## crypto.createHash(algorithm)
61 Creates and returns a hash object, a cryptographic hash with the given
62 algorithm which can be used to generate hash digests.
64 `algorithm` is dependent on the available algorithms supported by the
65 version of OpenSSL on the platform. Examples are `'sha1'`, `'md5'`,
66 `'sha256'`, `'sha512'`, etc. On recent releases, `openssl
67 list-message-digest-algorithms` will display the available digest
70 Example: this program that takes the sha1 sum of a file
72 var filename = process.argv[2];
73 var crypto = require('crypto');
74 var fs = require('fs');
76 var shasum = crypto.createHash('sha1');
78 var s = fs.ReadStream(filename);
79 s.on('data', function(d) {
83 s.on('end', function() {
84 var d = shasum.digest('hex');
85 console.log(d + ' ' + filename);
90 The class for creating hash digests of data.
92 It is a [stream](stream.html) that is both readable and writable. The
93 written data is used to compute the hash. Once the writable side of
94 the stream is ended, use the `read()` method to get the computed hash
95 digest. The legacy `update` and `digest` methods are also supported.
97 Returned by `crypto.createHash`.
99 ### hash.update(data, [input_encoding])
101 Updates the hash content with the given `data`, the encoding of which
102 is given in `input_encoding` and can be `'utf8'`, `'ascii'` or
103 `'binary'`. If no encoding is provided and the input is a string an
104 encoding of `'binary'` is enforced. If `data` is a `Buffer` then
105 `input_encoding` is ignored.
107 This can be called many times with new data as it is streamed.
109 ### hash.digest([encoding])
111 Calculates the digest of all of the passed data to be hashed. The
112 `encoding` can be `'hex'`, `'binary'` or `'base64'`. If no encoding
113 is provided, then a buffer is returned.
115 Note: `hash` object can not be used after `digest()` method has been
119 ## crypto.createHmac(algorithm, key)
121 Creates and returns a hmac object, a cryptographic hmac with the given
124 It is a [stream](stream.html) that is both readable and writable. The
125 written data is used to compute the hmac. Once the writable side of
126 the stream is ended, use the `read()` method to get the computed
127 digest. The legacy `update` and `digest` methods are also supported.
129 `algorithm` is dependent on the available algorithms supported by
130 OpenSSL - see createHash above. `key` is the hmac key to be used.
134 Class for creating cryptographic hmac content.
136 Returned by `crypto.createHmac`.
138 ### hmac.update(data)
140 Update the hmac content with the given `data`. This can be called
141 many times with new data as it is streamed.
143 ### hmac.digest([encoding])
145 Calculates the digest of all of the passed data to the hmac. The
146 `encoding` can be `'hex'`, `'binary'` or `'base64'`. If no encoding
147 is provided, then a buffer is returned.
149 Note: `hmac` object can not be used after `digest()` method has been
153 ## crypto.createCipher(algorithm, password)
155 Creates and returns a cipher object, with the given algorithm and
158 `algorithm` is dependent on OpenSSL, examples are `'aes192'`, etc. On
159 recent releases, `openssl list-cipher-algorithms` will display the
160 available cipher algorithms. `password` is used to derive key and IV,
161 which must be a `'binary'` encoded string or a [buffer](buffer.html).
163 It is a [stream](stream.html) that is both readable and writable. The
164 written data is used to compute the hash. Once the writable side of
165 the stream is ended, use the `read()` method to get the computed hash
166 digest. The legacy `update` and `digest` methods are also supported.
168 ## crypto.createCipheriv(algorithm, key, iv)
170 Creates and returns a cipher object, with the given algorithm, key and
173 `algorithm` is the same as the argument to `createCipher()`. `key` is
174 the raw key used by the algorithm. `iv` is an [initialization
175 vector](http://en.wikipedia.org/wiki/Initialization_vector).
177 `key` and `iv` must be `'binary'` encoded strings or
178 [buffers](buffer.html).
182 Class for encrypting data.
184 Returned by `crypto.createCipher` and `crypto.createCipheriv`.
186 Cipher objects are [streams](stream.html) that are both readable and
187 writable. The written plain text data is used to produce the
188 encrypted data on the readable side. The legacy `update` and `final`
189 methods are also supported.
191 ### cipher.update(data, [input_encoding], [output_encoding])
193 Updates the cipher with `data`, the encoding of which is given in
194 `input_encoding` and can be `'utf8'`, `'ascii'` or `'binary'`. If no
195 encoding is provided, then a buffer is expected.
196 If `data` is a `Buffer` then `input_encoding` is ignored.
198 The `output_encoding` specifies the output format of the enciphered
199 data, and can be `'binary'`, `'base64'` or `'hex'`. If no encoding is
200 provided, then a buffer is returned.
202 Returns the enciphered contents, and can be called many times with new
203 data as it is streamed.
205 ### cipher.final([output_encoding])
207 Returns any remaining enciphered contents, with `output_encoding`
208 being one of: `'binary'`, `'base64'` or `'hex'`. If no encoding is
209 provided, then a buffer is returned.
211 Note: `cipher` object can not be used after `final()` method has been
214 ### cipher.setAutoPadding(auto_padding=true)
216 You can disable automatic padding of the input data to block size. If
217 `auto_padding` is false, the length of the entire input data must be a
218 multiple of the cipher's block size or `final` will fail. Useful for
219 non-standard padding, e.g. using `0x0` instead of PKCS padding. You
220 must call this before `cipher.final`.
223 ## crypto.createDecipher(algorithm, password)
225 Creates and returns a decipher object, with the given algorithm and
226 key. This is the mirror of the [createCipher()][] above.
228 ## crypto.createDecipheriv(algorithm, key, iv)
230 Creates and returns a decipher object, with the given algorithm, key
231 and iv. This is the mirror of the [createCipheriv()][] above.
235 Class for decrypting data.
237 Returned by `crypto.createDecipher` and `crypto.createDecipheriv`.
239 Decipher objects are [streams](stream.html) that are both readable and
240 writable. The written enciphered data is used to produce the
241 plain-text data on the the readable side. The legacy `update` and
242 `final` methods are also supported.
244 ### decipher.update(data, [input_encoding], [output_encoding])
246 Updates the decipher with `data`, which is encoded in `'binary'`,
247 `'base64'` or `'hex'`. If no encoding is provided, then a buffer is
249 If `data` is a `Buffer` then `input_encoding` is ignored.
251 The `output_decoding` specifies in what format to return the
252 deciphered plaintext: `'binary'`, `'ascii'` or `'utf8'`. If no
253 encoding is provided, then a buffer is returned.
255 ### decipher.final([output_encoding])
257 Returns any remaining plaintext which is deciphered, with
258 `output_encoding` being one of: `'binary'`, `'ascii'` or `'utf8'`. If
259 no encoding is provided, then a buffer is returned.
261 Note: `decipher` object can not be used after `final()` method has been
264 ### decipher.setAutoPadding(auto_padding=true)
266 You can disable auto padding if the data has been encrypted without
267 standard block padding to prevent `decipher.final` from checking and
268 removing it. Can only work if the input data's length is a multiple of
269 the ciphers block size. You must call this before streaming data to
272 ## crypto.createSign(algorithm)
274 Creates and returns a signing object, with the given algorithm. On
275 recent OpenSSL releases, `openssl list-public-key-algorithms` will
276 display the available signing algorithms. Examples are `'RSA-SHA256'`.
280 Class for generating signatures.
282 Returned by `crypto.createSign`.
284 Sign objects are writable [streams](stream.html). The written data is
285 used to generate the signature. Once all of the data has been
286 written, the `sign` method will return the signature. The legacy
287 `update` method is also supported.
289 ### sign.update(data)
291 Updates the sign object with data. This can be called many times
292 with new data as it is streamed.
294 ### sign.sign(private_key, [output_format])
296 Calculates the signature on all the updated data passed through the
297 sign. `private_key` is a string containing the PEM encoded private
300 Returns the signature in `output_format` which can be `'binary'`,
301 `'hex'` or `'base64'`. If no encoding is provided, then a buffer is
304 Note: `sign` object can not be used after `sign()` method has been
307 ## crypto.createVerify(algorithm)
309 Creates and returns a verification object, with the given algorithm.
310 This is the mirror of the signing object above.
314 Class for verifying signatures.
316 Returned by `crypto.createVerify`.
318 Verify objects are writable [streams](stream.html). The written data
319 is used to validate against the supplied signature. Once all of the
320 data has been written, the `verify` method will return true if the
321 supplied signature is valid. The legacy `update` method is also
324 ### verifier.update(data)
326 Updates the verifier object with data. This can be called many times
327 with new data as it is streamed.
329 ### verifier.verify(object, signature, [signature_format])
331 Verifies the signed data by using the `object` and `signature`.
332 `object` is a string containing a PEM encoded object, which can be
333 one of RSA public key, DSA public key, or X.509 certificate.
334 `signature` is the previously calculated signature for the data, in
335 the `signature_format` which can be `'binary'`, `'hex'` or `'base64'`.
336 If no encoding is specified, then a buffer is expected.
338 Returns true or false depending on the validity of the signature for
339 the data and public key.
341 Note: `verifier` object can not be used after `verify()` method has been
344 ## crypto.createDiffieHellman(prime_length)
346 Creates a Diffie-Hellman key exchange object and generates a prime of
347 the given bit length. The generator used is `2`.
349 ## crypto.createDiffieHellman(prime, [encoding])
351 Creates a Diffie-Hellman key exchange object using the supplied prime.
352 The generator used is `2`. Encoding can be `'binary'`, `'hex'`, or
353 `'base64'`. If no encoding is specified, then a buffer is expected.
355 ## Class: DiffieHellman
357 The class for creating Diffie-Hellman key exchanges.
359 Returned by `crypto.createDiffieHellman`.
361 ### diffieHellman.generateKeys([encoding])
363 Generates private and public Diffie-Hellman key values, and returns
364 the public key in the specified encoding. This key should be
365 transferred to the other party. Encoding can be `'binary'`, `'hex'`,
366 or `'base64'`. If no encoding is provided, then a buffer is returned.
368 ### diffieHellman.computeSecret(other_public_key, [input_encoding], [output_encoding])
370 Computes the shared secret using `other_public_key` as the other
371 party's public key and returns the computed shared secret. Supplied
372 key is interpreted using specified `input_encoding`, and secret is
373 encoded using specified `output_encoding`. Encodings can be
374 `'binary'`, `'hex'`, or `'base64'`. If the input encoding is not
375 provided, then a buffer is expected.
377 If no output encoding is given, then a buffer is returned.
379 ### diffieHellman.getPrime([encoding])
381 Returns the Diffie-Hellman prime in the specified encoding, which can
382 be `'binary'`, `'hex'`, or `'base64'`. If no encoding is provided,
383 then a buffer is returned.
385 ### diffieHellman.getGenerator([encoding])
387 Returns the Diffie-Hellman generator in the specified encoding, which can
388 be `'binary'`, `'hex'`, or `'base64'`. If no encoding is provided,
389 then a buffer is returned.
391 ### diffieHellman.getPublicKey([encoding])
393 Returns the Diffie-Hellman public key in the specified encoding, which
394 can be `'binary'`, `'hex'`, or `'base64'`. If no encoding is provided,
395 then a buffer is returned.
397 ### diffieHellman.getPrivateKey([encoding])
399 Returns the Diffie-Hellman private key in the specified encoding,
400 which can be `'binary'`, `'hex'`, or `'base64'`. If no encoding is
401 provided, then a buffer is returned.
403 ### diffieHellman.setPublicKey(public_key, [encoding])
405 Sets the Diffie-Hellman public key. Key encoding can be `'binary'`,
406 `'hex'` or `'base64'`. If no encoding is provided, then a buffer is
409 ### diffieHellman.setPrivateKey(private_key, [encoding])
411 Sets the Diffie-Hellman private key. Key encoding can be `'binary'`,
412 `'hex'` or `'base64'`. If no encoding is provided, then a buffer is
415 ## crypto.getDiffieHellman(group_name)
417 Creates a predefined Diffie-Hellman key exchange object. The
418 supported groups are: `'modp1'`, `'modp2'`, `'modp5'` (defined in [RFC
419 2412][]) and `'modp14'`, `'modp15'`, `'modp16'`, `'modp17'`,
420 `'modp18'` (defined in [RFC 3526][]). The returned object mimics the
421 interface of objects created by [crypto.createDiffieHellman()][]
422 above, but will not allow to change the keys (with
423 [diffieHellman.setPublicKey()][] for example). The advantage of using
424 this routine is that the parties don't have to generate nor exchange
425 group modulus beforehand, saving both processor and communication
428 Example (obtaining a shared secret):
430 var crypto = require('crypto');
431 var alice = crypto.getDiffieHellman('modp5');
432 var bob = crypto.getDiffieHellman('modp5');
434 alice.generateKeys();
437 var alice_secret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
438 var bob_secret = bob.computeSecret(alice.getPublicKey(), null, 'hex');
440 /* alice_secret and bob_secret should be the same */
441 console.log(alice_secret == bob_secret);
443 ## crypto.pbkdf2(password, salt, iterations, keylen, callback)
445 Asynchronous PBKDF2 applies pseudorandom function HMAC-SHA1 to derive
446 a key of given length from the given password, salt and iterations.
447 The callback gets two arguments `(err, derivedKey)`.
449 ## crypto.pbkdf2Sync(password, salt, iterations, keylen)
451 Synchronous PBKDF2 function. Returns derivedKey or throws error.
453 ## crypto.randomBytes(size, [callback])
455 Generates cryptographically strong pseudo-random data. Usage:
458 crypto.randomBytes(256, function(ex, buf) {
460 console.log('Have %d bytes of random data: %s', buf.length, buf);
465 var buf = crypto.randomBytes(256);
466 console.log('Have %d bytes of random data: %s', buf.length, buf);
469 // most likely, entropy sources are drained
472 NOTE: Will throw error or invoke callback with error, if there is not enough
473 accumulated entropy to generate cryptographically strong data. In other words,
474 `crypto.randomBytes` without callback will not block even if all entropy sources
477 ## crypto.pseudoRandomBytes(size, [callback])
479 Generates *non*-cryptographically strong pseudo-random data. The data
480 returned will be unique if it is sufficiently long, but is not
481 necessarily unpredictable. For this reason, the output of this
482 function should never be used where unpredictability is important,
483 such as in the generation of encryption keys.
485 Usage is otherwise identical to `crypto.randomBytes`.
487 ## crypto.DEFAULT_ENCODING
489 The default encoding to use for functions that can take either strings
490 or buffers. The default value is `'buffer'`, which makes it default
491 to using Buffer objects. This is here to make the crypto module more
492 easily compatible with legacy programs that expected `'binary'` to be
493 the default encoding.
495 Note that new programs will probably expect buffers, so only use this
496 as a temporary measure.
498 ## Recent API Changes
500 The Crypto module was added to Node before there was the concept of a
501 unified Stream API, and before there were Buffer objects for handling
504 As such, the streaming classes don't have the typical methods found on
505 other Node classes, and many methods accepted and returned
506 Binary-encoded strings by default rather than Buffers. This was
507 changed to use Buffers by default instead.
509 This is a breaking change for some use cases, but not all.
511 For example, if you currently use the default arguments to the Sign
512 class, and then pass the results to the Verify class, without ever
513 inspecting the data, then it will continue to work as before. Where
514 you once got a binary string and then presented the binary string to
515 the Verify object, you'll now get a Buffer, and present the Buffer to
518 However, if you were doing things with the string data that will not
519 work properly on Buffers (such as, concatenating them, storing in
520 databases, etc.), or you are passing binary strings to the crypto
521 functions without an encoding argument, then you will need to start
522 providing encoding arguments to specify which encoding you'd like to
523 use. To switch to the previous style of using binary strings by
524 default, set the `crypto.DEFAULT_ENCODING` field to 'binary'. Note
525 that new programs will probably expect buffers, so only use this as a
529 [createCipher()]: #crypto_crypto_createcipher_algorithm_password
530 [createCipheriv()]: #crypto_crypto_createcipheriv_algorithm_key_iv
531 [crypto.createDiffieHellman()]: #crypto_crypto_creatediffiehellman_prime_encoding
532 [diffieHellman.setPublicKey()]: #crypto_diffiehellman_setpublickey_public_key_encoding
533 [RFC 2412]: http://www.rfc-editor.org/rfc/rfc2412.txt
534 [RFC 3526]: http://www.rfc-editor.org/rfc/rfc3526.txt