6 enc - symmetric cipher routines
10 B<openssl enc -I<cipher>>
43 B<openssl> I<[cipher]> [B<...>]
47 The symmetric cipher commands allow data to be encrypted or decrypted
48 using various block and stream ciphers using keys based on passwords
49 or explicitly provided. Base64 encoding or decoding can also be performed
50 either by itself or in addition to the encryption or decryption.
58 Print out a usage message.
62 List all supported ciphers.
66 Alias of -list to display all supported ciphers.
70 The input filename, standard input by default.
72 =item B<-out filename>
74 The output filename, standard output by default.
78 The password source. For more information about the format of B<arg>
79 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
83 Encrypt the input data: this is the default.
87 Decrypt the input data.
91 Base64 process the data. This means that if encryption is taking place
92 the data is base64 encoded after encryption. If decryption is set then
93 the input data is base64 decoded before being decrypted.
101 If the B<-a> option is set then base64 process the data on one line.
105 The password to derive the key from. This is for compatibility with previous
106 versions of OpenSSL. Superseded by the B<-pass> argument.
108 =item B<-kfile filename>
110 Read the password to derive the key from the first line of B<filename>.
111 This is for compatibility with previous versions of OpenSSL. Superseded by
112 the B<-pass> argument.
116 Use the specified digest to create the key from the passphrase.
117 The default algorithm is sha-256.
121 Use a given number of iterations on the password in deriving the encryption key.
122 High values increase the time required to brute-force the resulting file.
123 This option enables the use of PBKDF2 algorithm to derive the key.
127 Use PBKDF2 algorithm with default iteration count unless otherwise specified.
131 Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
132 used except for test purposes or compatibility with ancient versions of
137 Use salt (randomly generated or provide with B<-S> option) when
138 encrypting, this is the default.
142 The actual salt to use: this must be represented as a string of hex digits.
146 The actual key to use: this must be represented as a string comprised only
147 of hex digits. If only the key is specified, the IV must additionally specified
148 using the B<-iv> option. When both a key and a password are specified, the
149 key given with the B<-K> option will be used and the IV generated from the
150 password will be taken. It does not make much sense to specify both key
155 The actual IV to use: this must be represented as a string comprised only
156 of hex digits. When only the key is specified using the B<-K> option, the
157 IV must explicitly be defined. When a password is being specified using
158 one of the other options, the IV is generated from this password.
162 Print out the key and IV used.
166 Print out the key and IV used then immediately exit: don't do any encryption
169 =item B<-bufsize number>
171 Set the buffer size for I/O.
175 Disable standard block padding.
179 Debug the BIOs used for I/O.
183 Compress or decompress clear text using zlib before encryption or after
184 decryption. This option exists only if OpenSSL with compiled with zlib
185 or zlib-dynamic option.
189 Use NULL cipher (no encryption or decryption of input).
191 =item B<-rand file...>
193 A file or files containing random data used to seed the random number
195 Multiple files can be specified separated by an OS-dependent character.
196 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
199 =item [B<-writerand file>]
201 Writes random data to the specified I<file> upon exit.
202 This can be used with a subsequent B<-rand> flag.
208 The program can be called either as B<openssl cipher> or
209 B<openssl enc -cipher>. The first form doesn't work with
210 engine-provided ciphers, because this form is processed before the
211 configuration file is read and any ENGINEs loaded.
212 Use the B<list> command to get a list of supported ciphers.
214 Engines which provide entirely new encryption algorithms (such as the ccgost
215 engine which provides gost89 algorithm) should be configured in the
216 configuration file. Engines specified on the command line using -engine
217 options can only be used for hardware-assisted implementations of
218 ciphers which are supported by the OpenSSL core or another engine specified
219 in the configuration file.
221 When the enc command lists supported ciphers, ciphers provided by engines,
222 specified in the configuration files are listed too.
224 A password will be prompted for to derive the key and IV if necessary.
226 The B<-salt> option should B<ALWAYS> be used if the key is being derived
227 from a password unless you want compatibility with previous versions of
230 Without the B<-salt> option it is possible to perform efficient dictionary
231 attacks on the password and to attack stream cipher encrypted data. The reason
232 for this is that without the salt the same password always generates the same
233 encryption key. When the salt is being used the first eight bytes of the
234 encrypted data are reserved for the salt: it is generated at random when
235 encrypting a file and read from the encrypted file when it is decrypted.
237 Some of the ciphers do not have large keys and others have security
238 implications if not used correctly. A beginner is advised to just use
239 a strong block cipher, such as AES, in CBC mode.
241 All the block ciphers normally use PKCS#5 padding, also known as standard
242 block padding. This allows a rudimentary integrity or password check to
243 be performed. However, since the chance of random data passing the test
244 is better than 1 in 256 it isn't a very good test.
246 If padding is disabled then the input data must be a multiple of the cipher
249 All RC2 ciphers have the same key and effective key length.
251 Blowfish and RC5 algorithms use a 128 bit key.
253 =head1 SUPPORTED CIPHERS
255 Note that some of these ciphers can be disabled at compile time
256 and some are available only if an appropriate engine is configured
257 in the configuration file. The output of the B<enc> command run with
258 the B<-ciphers> option (that is B<openssl enc -ciphers>) produces a
259 list of ciphers, supported by your version of OpenSSL, including
260 ones provided by configured engines.
262 The B<enc> program does not support authenticated encryption modes
263 like CCM and GCM, and will not support such modes in the future.
264 The B<enc> interface by necessity must begin streaming output (e.g.,
265 to standard output when B<-out> is not used) before the authentication
266 tag could be validated, leading to the usage of B<enc> in pipelines
267 that begin processing untrusted data and are not capable of rolling
268 back upon authentication failure. The AEAD modes currently in common
269 use also suffer from catastrophic failure of confidentiality and/or
270 integrity upon reuse of key/iv/nonce, and since B<enc> places the
271 entire burden of key/iv/nonce management upon the user, the risk of
272 exposing AEAD modes is too great to allow. These key/iv/nonce
273 management issues also affect other modes currently exposed in B<enc>,
274 but the failure modes are less extreme in these cases, and the
275 functionality cannot be removed with a stable release branch.
276 For bulk encryption of data, whether using authenticated encryption
277 modes or other modes, L<cms(1)> is recommended, as it provides a
278 standard data format and performs the needed key/iv/nonce management.
283 bf-cbc Blowfish in CBC mode
285 blowfish Alias for bf-cbc
286 bf-cfb Blowfish in CFB mode
287 bf-ecb Blowfish in ECB mode
288 bf-ofb Blowfish in OFB mode
290 cast-cbc CAST in CBC mode
291 cast Alias for cast-cbc
292 cast5-cbc CAST5 in CBC mode
293 cast5-cfb CAST5 in CFB mode
294 cast5-ecb CAST5 in ECB mode
295 cast5-ofb CAST5 in OFB mode
297 chacha20 ChaCha20 algorithm
299 des-cbc DES in CBC mode
300 des Alias for des-cbc
301 des-cfb DES in CFB mode
302 des-ofb DES in OFB mode
303 des-ecb DES in ECB mode
305 des-ede-cbc Two key triple DES EDE in CBC mode
306 des-ede Two key triple DES EDE in ECB mode
307 des-ede-cfb Two key triple DES EDE in CFB mode
308 des-ede-ofb Two key triple DES EDE in OFB mode
310 des-ede3-cbc Three key triple DES EDE in CBC mode
311 des-ede3 Three key triple DES EDE in ECB mode
312 des3 Alias for des-ede3-cbc
313 des-ede3-cfb Three key triple DES EDE CFB mode
314 des-ede3-ofb Three key triple DES EDE in OFB mode
318 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
319 gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
321 idea-cbc IDEA algorithm in CBC mode
322 idea same as idea-cbc
323 idea-cfb IDEA in CFB mode
324 idea-ecb IDEA in ECB mode
325 idea-ofb IDEA in OFB mode
327 rc2-cbc 128 bit RC2 in CBC mode
328 rc2 Alias for rc2-cbc
329 rc2-cfb 128 bit RC2 in CFB mode
330 rc2-ecb 128 bit RC2 in ECB mode
331 rc2-ofb 128 bit RC2 in OFB mode
332 rc2-64-cbc 64 bit RC2 in CBC mode
333 rc2-40-cbc 40 bit RC2 in CBC mode
339 rc5-cbc RC5 cipher in CBC mode
340 rc5 Alias for rc5-cbc
341 rc5-cfb RC5 cipher in CFB mode
342 rc5-ecb RC5 cipher in ECB mode
343 rc5-ofb RC5 cipher in OFB mode
345 seed-cbc SEED cipher in CBC mode
346 seed Alias for seed-cbc
347 seed-cfb SEED cipher in CFB mode
348 seed-ecb SEED cipher in ECB mode
349 seed-ofb SEED cipher in OFB mode
351 sm4-cbc SM4 cipher in CBC mode
352 sm4 Alias for sm4-cbc
353 sm4-cfb SM4 cipher in CFB mode
354 sm4-ctr SM4 cipher in CTR mode
355 sm4-ecb SM4 cipher in ECB mode
356 sm4-ofb SM4 cipher in OFB mode
358 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
359 aes[128|192|256] Alias for aes-[128|192|256]-cbc
360 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
361 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
362 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
363 aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode
364 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
365 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
367 aria-[128|192|256]-cbc 128/192/256 bit ARIA in CBC mode
368 aria[128|192|256] Alias for aria-[128|192|256]-cbc
369 aria-[128|192|256]-cfb 128/192/256 bit ARIA in 128 bit CFB mode
370 aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
371 aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
372 aria-[128|192|256]-ctr 128/192/256 bit ARIA in CTR mode
373 aria-[128|192|256]-ecb 128/192/256 bit ARIA in ECB mode
374 aria-[128|192|256]-ofb 128/192/256 bit ARIA in OFB mode
376 camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
377 camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
378 camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
379 camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
380 camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
381 camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
382 camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
383 camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
387 Just base64 encode a binary file:
389 openssl base64 -in file.bin -out file.b64
393 openssl base64 -d -in file.b64 -out file.bin
395 Encrypt a file using AES-128 using a prompted password
396 and PBKDF2 key derivation:
398 openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
400 Decrypt a file using a supplied password:
402 openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
403 -pass pass:<password>
405 Encrypt a file then base64 encode it (so it can be sent via mail for example)
406 using AES-256 in CTR mode and PBKDF2 key derivation:
408 openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
410 Base64 decode a file then decrypt it using a password supplied in a file:
412 openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
413 -pass file:<passfile>
417 The B<-A> option when used with large files doesn't work properly.
419 The B<enc> program only supports a fixed number of algorithms with
420 certain parameters. So if, for example, you want to use RC2 with a
421 76 bit key or RC4 with an 84 bit key you can't use this program.
425 The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
427 The B<-list> option was added in OpenSSL 1.1.1e.
431 Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
433 Licensed under the OpenSSL license (the "License"). You may not use
434 this file except in compliance with the License. You can obtain a copy
435 in the file LICENSE in the source distribution or at
436 L<https://www.openssl.org/source/license.html>.