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, then a buffer is expected.
104 If `data` is a `Buffer` then `input_encoding` is ignored.
106 This can be called many times with new data as it is streamed.
108 ### hash.digest([encoding])
110 Calculates the digest of all of the passed data to be hashed. The
111 `encoding` can be `'hex'`, `'binary'` or `'base64'`. If no encoding
112 is provided, then a buffer is returned.
114 Note: `hash` object can not be used after `digest()` method has been
118 ## crypto.createHmac(algorithm, key)
120 Creates and returns a hmac object, a cryptographic hmac with the given
123 It is a [stream](stream.html) that is both readable and writable. The
124 written data is used to compute the hmac. Once the writable side of
125 the stream is ended, use the `read()` method to get the computed
126 digest. The legacy `update` and `digest` methods are also supported.
128 `algorithm` is dependent on the available algorithms supported by
129 OpenSSL - see createHash above. `key` is the hmac key to be used.
133 Class for creating cryptographic hmac content.
135 Returned by `crypto.createHmac`.
137 ### hmac.update(data)
139 Update the hmac content with the given `data`. This can be called
140 many times with new data as it is streamed.
142 ### hmac.digest([encoding])
144 Calculates the digest of all of the passed data to the hmac. The
145 `encoding` can be `'hex'`, `'binary'` or `'base64'`. If no encoding
146 is provided, then a buffer is returned.
148 Note: `hmac` object can not be used after `digest()` method has been
152 ## crypto.createCipher(algorithm, password)
154 Creates and returns a cipher object, with the given algorithm and
157 `algorithm` is dependent on OpenSSL, examples are `'aes192'`, etc. On
158 recent releases, `openssl list-cipher-algorithms` will display the
159 available cipher algorithms. `password` is used to derive key and IV,
160 which must be a `'binary'` encoded string or a [buffer](buffer.html).
162 It is a [stream](stream.html) that is both readable and writable. The
163 written data is used to compute the hash. Once the writable side of
164 the stream is ended, use the `read()` method to get the computed hash
165 digest. The legacy `update` and `digest` methods are also supported.
167 ## crypto.createCipheriv(algorithm, key, iv)
169 Creates and returns a cipher object, with the given algorithm, key and
172 `algorithm` is the same as the argument to `createCipher()`. `key` is
173 the raw key used by the algorithm. `iv` is an [initialization
174 vector](http://en.wikipedia.org/wiki/Initialization_vector).
176 `key` and `iv` must be `'binary'` encoded strings or
177 [buffers](buffer.html).
181 Class for encrypting data.
183 Returned by `crypto.createCipher` and `crypto.createCipheriv`.
185 Cipher objects are [streams](stream.html) that are both readable and
186 writable. The written plain text data is used to produce the
187 encrypted data on the readable side. The legacy `update` and `final`
188 methods are also supported.
190 ### cipher.update(data, [input_encoding], [output_encoding])
192 Updates the cipher with `data`, the encoding of which is given in
193 `input_encoding` and can be `'utf8'`, `'ascii'` or `'binary'`. If no
194 encoding is provided, then a buffer is expected.
195 If `data` is a `Buffer` then `input_encoding` is ignored.
197 The `output_encoding` specifies the output format of the enciphered
198 data, and can be `'binary'`, `'base64'` or `'hex'`. If no encoding is
199 provided, then a buffer is returned.
201 Returns the enciphered contents, and can be called many times with new
202 data as it is streamed.
204 ### cipher.final([output_encoding])
206 Returns any remaining enciphered contents, with `output_encoding`
207 being one of: `'binary'`, `'base64'` or `'hex'`. If no encoding is
208 provided, then a buffer is returned.
210 Note: `cipher` object can not be used after `final()` method has been
213 ### cipher.setAutoPadding(auto_padding=true)
215 You can disable automatic padding of the input data to block size. If
216 `auto_padding` is false, the length of the entire input data must be a
217 multiple of the cipher's block size or `final` will fail. Useful for
218 non-standard padding, e.g. using `0x0` instead of PKCS padding. You
219 must call this before `cipher.final`.
221 ### cipher.getAuthTag()
223 For authenticated encryption modes (currently supported: GCM), this
224 method returns a `Buffer` that represents the _authentication tag_ that
225 has been computed from the given data. Should be called after
226 encryption has been completed using the `final` method!
229 ## crypto.createDecipher(algorithm, password)
231 Creates and returns a decipher object, with the given algorithm and
232 key. This is the mirror of the [createCipher()][] above.
234 ## crypto.createDecipheriv(algorithm, key, iv)
236 Creates and returns a decipher object, with the given algorithm, key
237 and iv. This is the mirror of the [createCipheriv()][] above.
241 Class for decrypting data.
243 Returned by `crypto.createDecipher` and `crypto.createDecipheriv`.
245 Decipher objects are [streams](stream.html) that are both readable and
246 writable. The written enciphered data is used to produce the
247 plain-text data on the the readable side. The legacy `update` and
248 `final` methods are also supported.
250 ### decipher.update(data, [input_encoding], [output_encoding])
252 Updates the decipher with `data`, which is encoded in `'binary'`,
253 `'base64'` or `'hex'`. If no encoding is provided, then a buffer is
255 If `data` is a `Buffer` then `input_encoding` is ignored.
257 The `output_decoding` specifies in what format to return the
258 deciphered plaintext: `'binary'`, `'ascii'` or `'utf8'`. If no
259 encoding is provided, then a buffer is returned.
261 ### decipher.final([output_encoding])
263 Returns any remaining plaintext which is deciphered, with
264 `output_encoding` being one of: `'binary'`, `'ascii'` or `'utf8'`. If
265 no encoding is provided, then a buffer is returned.
267 Note: `decipher` object can not be used after `final()` method has been
270 ### decipher.setAutoPadding(auto_padding=true)
272 You can disable auto padding if the data has been encrypted without
273 standard block padding to prevent `decipher.final` from checking and
274 removing it. Can only work if the input data's length is a multiple of
275 the ciphers block size. You must call this before streaming data to
278 ### decipher.setAuthTag(buffer)
280 For authenticated encryption modes (currently supported: GCM), this
281 method must be used to pass in the received _authentication tag_.
282 If no tag is provided or if the ciphertext has been tampered with,
283 `final` will throw, thus indicating that the ciphertext should
284 be discarded due to failed authentication.
287 ## crypto.createSign(algorithm)
289 Creates and returns a signing object, with the given algorithm. On
290 recent OpenSSL releases, `openssl list-public-key-algorithms` will
291 display the available signing algorithms. Examples are `'RSA-SHA256'`.
295 Class for generating signatures.
297 Returned by `crypto.createSign`.
299 Sign objects are writable [streams](stream.html). The written data is
300 used to generate the signature. Once all of the data has been
301 written, the `sign` method will return the signature. The legacy
302 `update` method is also supported.
304 ### sign.update(data)
306 Updates the sign object with data. This can be called many times
307 with new data as it is streamed.
309 ### sign.sign(private_key, [output_format])
311 Calculates the signature on all the updated data passed through the
314 `private_key` can be an object or a string. If `private_key` is a string, it is
315 treated as the key with no passphrase.
319 * `key` : A string holding the PEM encoded private key
320 * `passphrase` : A string of passphrase for the private key
322 Returns the signature in `output_format` which can be `'binary'`,
323 `'hex'` or `'base64'`. If no encoding is provided, then a buffer is
326 Note: `sign` object can not be used after `sign()` method has been
329 ## crypto.createVerify(algorithm)
331 Creates and returns a verification object, with the given algorithm.
332 This is the mirror of the signing object above.
336 Class for verifying signatures.
338 Returned by `crypto.createVerify`.
340 Verify objects are writable [streams](stream.html). The written data
341 is used to validate against the supplied signature. Once all of the
342 data has been written, the `verify` method will return true if the
343 supplied signature is valid. The legacy `update` method is also
346 ### verifier.update(data)
348 Updates the verifier object with data. This can be called many times
349 with new data as it is streamed.
351 ### verifier.verify(object, signature, [signature_format])
353 Verifies the signed data by using the `object` and `signature`.
354 `object` is a string containing a PEM encoded object, which can be
355 one of RSA public key, DSA public key, or X.509 certificate.
356 `signature` is the previously calculated signature for the data, in
357 the `signature_format` which can be `'binary'`, `'hex'` or `'base64'`.
358 If no encoding is specified, then a buffer is expected.
360 Returns true or false depending on the validity of the signature for
361 the data and public key.
363 Note: `verifier` object can not be used after `verify()` method has been
366 ## crypto.createDiffieHellman(prime_length)
368 Creates a Diffie-Hellman key exchange object and generates a prime of
369 the given bit length. The generator used is `2`.
371 ## crypto.createDiffieHellman(prime, [encoding])
373 Creates a Diffie-Hellman key exchange object using the supplied prime.
374 The generator used is `2`. Encoding can be `'binary'`, `'hex'`, or
375 `'base64'`. If no encoding is specified, then a buffer is expected.
377 ## Class: DiffieHellman
379 The class for creating Diffie-Hellman key exchanges.
381 Returned by `crypto.createDiffieHellman`.
383 ### diffieHellman.generateKeys([encoding])
385 Generates private and public Diffie-Hellman key values, and returns
386 the public key in the specified encoding. This key should be
387 transferred to the other party. Encoding can be `'binary'`, `'hex'`,
388 or `'base64'`. If no encoding is provided, then a buffer is returned.
390 ### diffieHellman.computeSecret(other_public_key, [input_encoding], [output_encoding])
392 Computes the shared secret using `other_public_key` as the other
393 party's public key and returns the computed shared secret. Supplied
394 key is interpreted using specified `input_encoding`, and secret is
395 encoded using specified `output_encoding`. Encodings can be
396 `'binary'`, `'hex'`, or `'base64'`. If the input encoding is not
397 provided, then a buffer is expected.
399 If no output encoding is given, then a buffer is returned.
401 ### diffieHellman.getPrime([encoding])
403 Returns the Diffie-Hellman prime in the specified encoding, which can
404 be `'binary'`, `'hex'`, or `'base64'`. If no encoding is provided,
405 then a buffer is returned.
407 ### diffieHellman.getGenerator([encoding])
409 Returns the Diffie-Hellman prime in the specified encoding, which can
410 be `'binary'`, `'hex'`, or `'base64'`. If no encoding is provided,
411 then a buffer is returned.
413 ### diffieHellman.getPublicKey([encoding])
415 Returns the Diffie-Hellman public key in the specified encoding, which
416 can be `'binary'`, `'hex'`, or `'base64'`. If no encoding is provided,
417 then a buffer is returned.
419 ### diffieHellman.getPrivateKey([encoding])
421 Returns the Diffie-Hellman private key in the specified encoding,
422 which can be `'binary'`, `'hex'`, or `'base64'`. If no encoding is
423 provided, then a buffer is returned.
425 ### diffieHellman.setPublicKey(public_key, [encoding])
427 Sets the Diffie-Hellman public key. Key encoding can be `'binary'`,
428 `'hex'` or `'base64'`. If no encoding is provided, then a buffer is
431 ### diffieHellman.setPrivateKey(private_key, [encoding])
433 Sets the Diffie-Hellman private key. Key encoding can be `'binary'`,
434 `'hex'` or `'base64'`. If no encoding is provided, then a buffer is
437 ## crypto.getDiffieHellman(group_name)
439 Creates a predefined Diffie-Hellman key exchange object. The
440 supported groups are: `'modp1'`, `'modp2'`, `'modp5'` (defined in [RFC
441 2412][]) and `'modp14'`, `'modp15'`, `'modp16'`, `'modp17'`,
442 `'modp18'` (defined in [RFC 3526][]). The returned object mimics the
443 interface of objects created by [crypto.createDiffieHellman()][]
444 above, but will not allow to change the keys (with
445 [diffieHellman.setPublicKey()][] for example). The advantage of using
446 this routine is that the parties don't have to generate nor exchange
447 group modulus beforehand, saving both processor and communication
450 Example (obtaining a shared secret):
452 var crypto = require('crypto');
453 var alice = crypto.getDiffieHellman('modp5');
454 var bob = crypto.getDiffieHellman('modp5');
456 alice.generateKeys();
459 var alice_secret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
460 var bob_secret = bob.computeSecret(alice.getPublicKey(), null, 'hex');
462 /* alice_secret and bob_secret should be the same */
463 console.log(alice_secret == bob_secret);
465 ## crypto.pbkdf2(password, salt, iterations, keylen, callback)
467 Asynchronous PBKDF2 applies pseudorandom function HMAC-SHA1 to derive
468 a key of given length from the given password, salt and iterations.
469 The callback gets two arguments `(err, derivedKey)`.
471 ## crypto.pbkdf2Sync(password, salt, iterations, keylen)
473 Synchronous PBKDF2 function. Returns derivedKey or throws error.
475 ## crypto.randomBytes(size, [callback])
477 Generates cryptographically strong pseudo-random data. Usage:
480 crypto.randomBytes(256, function(ex, buf) {
482 console.log('Have %d bytes of random data: %s', buf.length, buf);
487 var buf = crypto.randomBytes(256);
488 console.log('Have %d bytes of random data: %s', buf.length, buf);
491 // most likely, entropy sources are drained
494 NOTE: Will throw error or invoke callback with error, if there is not enough
495 accumulated entropy to generate cryptographically strong data. In other words,
496 `crypto.randomBytes` without callback will not block even if all entropy sources
499 ## crypto.pseudoRandomBytes(size, [callback])
501 Generates *non*-cryptographically strong pseudo-random data. The data
502 returned will be unique if it is sufficiently long, but is not
503 necessarily unpredictable. For this reason, the output of this
504 function should never be used where unpredictability is important,
505 such as in the generation of encryption keys.
507 Usage is otherwise identical to `crypto.randomBytes`.
509 ## Class: Certificate
511 The class used for working with signed public key & challenges. The most
512 common usage for this series of functions is when dealing with the `<keygen>`
513 element. http://www.openssl.org/docs/apps/spkac.html
515 Returned by `crypto.Certificate`.
517 ### Certificate.verifySpkac(spkac)
519 Returns true of false based on the validity of the SPKAC.
521 ### Certificate.exportChallenge(spkac)
523 Exports the encoded public key from the supplied SPKAC.
525 ### Certificate.exportPublicKey(spkac)
527 Exports the encoded challenge associated with the SPKAC.
529 ## crypto.DEFAULT_ENCODING
531 The default encoding to use for functions that can take either strings
532 or buffers. The default value is `'buffer'`, which makes it default
533 to using Buffer objects. This is here to make the crypto module more
534 easily compatible with legacy programs that expected `'binary'` to be
535 the default encoding.
537 Note that new programs will probably expect buffers, so only use this
538 as a temporary measure.
540 ## Recent API Changes
542 The Crypto module was added to Node before there was the concept of a
543 unified Stream API, and before there were Buffer objects for handling
546 As such, the streaming classes don't have the typical methods found on
547 other Node classes, and many methods accepted and returned
548 Binary-encoded strings by default rather than Buffers. This was
549 changed to use Buffers by default instead.
551 This is a breaking change for some use cases, but not all.
553 For example, if you currently use the default arguments to the Sign
554 class, and then pass the results to the Verify class, without ever
555 inspecting the data, then it will continue to work as before. Where
556 you once got a binary string and then presented the binary string to
557 the Verify object, you'll now get a Buffer, and present the Buffer to
560 However, if you were doing things with the string data that will not
561 work properly on Buffers (such as, concatenating them, storing in
562 databases, etc.), or you are passing binary strings to the crypto
563 functions without an encoding argument, then you will need to start
564 providing encoding arguments to specify which encoding you'd like to
565 use. To switch to the previous style of using binary strings by
566 default, set the `crypto.DEFAULT_ENCODING` field to 'binary'. Note
567 that new programs will probably expect buffers, so only use this as a
571 [createCipher()]: #crypto_crypto_createcipher_algorithm_password
572 [createCipheriv()]: #crypto_crypto_createcipheriv_algorithm_key_iv
573 [crypto.createDiffieHellman()]: #crypto_crypto_creatediffiehellman_prime_encoding
574 [diffieHellman.setPublicKey()]: #crypto_diffiehellman_setpublickey_public_key_encoding
575 [RFC 2412]: http://www.rfc-editor.org/rfc/rfc2412.txt
576 [RFC 3526]: http://www.rfc-editor.org/rfc/rfc3526.txt