6 enc - symmetric cipher routines
10 B<openssl enc -I<cipher>>
42 B<openssl> I<[cipher]> [B<...>]
46 The symmetric cipher commands allow data to be encrypted or decrypted
47 using various block and stream ciphers using keys based on passwords
48 or explicitly provided. Base64 encoding or decoding can also be performed
49 either by itself or in addition to the encryption or decryption.
57 Print out a usage message.
61 List all supported ciphers.
65 The input filename, standard input by default.
67 =item B<-out filename>
69 The output filename, standard output by default.
73 The password source. For more information about the format of B<arg>
74 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
78 Encrypt the input data: this is the default.
82 Decrypt the input data.
86 Base64 process the data. This means that if encryption is taking place
87 the data is base64 encoded after encryption. If decryption is set then
88 the input data is base64 decoded before being decrypted.
96 If the B<-a> option is set then base64 process the data on one line.
100 The password to derive the key from. This is for compatibility with previous
101 versions of OpenSSL. Superseded by the B<-pass> argument.
103 =item B<-kfile filename>
105 Read the password to derive the key from the first line of B<filename>.
106 This is for compatibility with previous versions of OpenSSL. Superseded by
107 the B<-pass> argument.
111 Use the specified digest to create the key from the passphrase.
112 The default algorithm is sha-256.
116 Use a given number of iterations on the password in deriving the encryption key.
117 High values increase the time required to brute-force the resulting file.
118 This option enables the use of PBKDF2 algorithm to derive the key.
122 Use PBKDF2 algorithm with default iteration count unless otherwise specified.
126 Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
127 used except for test purposes or compatibility with ancient versions of
132 Use salt (randomly generated or provide with B<-S> option) when
133 encrypting, this is the default.
137 The actual salt to use: this must be represented as a string of hex digits.
141 The actual key to use: this must be represented as a string comprised only
142 of hex digits. If only the key is specified, the IV must additionally specified
143 using the B<-iv> option. When both a key and a password are specified, the
144 key given with the B<-K> option will be used and the IV generated from the
145 password will be taken. It does not make much sense to specify both key
150 The actual IV to use: this must be represented as a string comprised only
151 of hex digits. When only the key is specified using the B<-K> option, the
152 IV must explicitly be defined. When a password is being specified using
153 one of the other options, the IV is generated from this password.
157 Print out the key and IV used.
161 Print out the key and IV used then immediately exit: don't do any encryption
164 =item B<-bufsize number>
166 Set the buffer size for I/O.
170 Disable standard block padding.
174 Debug the BIOs used for I/O.
178 Compress or decompress clear text using zlib before encryption or after
179 decryption. This option exists only if OpenSSL with compiled with zlib
180 or zlib-dynamic option.
184 Use NULL cipher (no encryption or decryption of input).
186 =item B<-rand file...>
188 A file or files containing random data used to seed the random number
190 Multiple files can be specified separated by an OS-dependent character.
191 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
194 =item [B<-writerand file>]
196 Writes random data to the specified I<file> upon exit.
197 This can be used with a subsequent B<-rand> flag.
203 The program can be called either as B<openssl cipher> or
204 B<openssl enc -cipher>. The first form doesn't work with
205 engine-provided ciphers, because this form is processed before the
206 configuration file is read and any ENGINEs loaded.
207 Use the B<list> command to get a list of supported ciphers.
209 Engines which provide entirely new encryption algorithms (such as the ccgost
210 engine which provides gost89 algorithm) should be configured in the
211 configuration file. Engines specified on the command line using -engine
212 options can only be used for hardware-assisted implementations of
213 ciphers which are supported by the OpenSSL core or another engine specified
214 in the configuration file.
216 When the enc command lists supported ciphers, ciphers provided by engines,
217 specified in the configuration files are listed too.
219 A password will be prompted for to derive the key and IV if necessary.
221 The B<-salt> option should B<ALWAYS> be used if the key is being derived
222 from a password unless you want compatibility with previous versions of
225 Without the B<-salt> option it is possible to perform efficient dictionary
226 attacks on the password and to attack stream cipher encrypted data. The reason
227 for this is that without the salt the same password always generates the same
228 encryption key. When the salt is being used the first eight bytes of the
229 encrypted data are reserved for the salt: it is generated at random when
230 encrypting a file and read from the encrypted file when it is decrypted.
232 Some of the ciphers do not have large keys and others have security
233 implications if not used correctly. A beginner is advised to just use
234 a strong block cipher, such as AES, in CBC mode.
236 All the block ciphers normally use PKCS#5 padding, also known as standard
237 block padding. This allows a rudimentary integrity or password check to
238 be performed. However since the chance of random data passing the test
239 is better than 1 in 256 it isn't a very good test.
241 If padding is disabled then the input data must be a multiple of the cipher
244 All RC2 ciphers have the same key and effective key length.
246 Blowfish and RC5 algorithms use a 128 bit key.
248 =head1 SUPPORTED CIPHERS
250 Note that some of these ciphers can be disabled at compile time
251 and some are available only if an appropriate engine is configured
252 in the configuration file. The output of the B<enc> command run with
253 the B<-ciphers> option (that is B<openssl enc -ciphers>) produces a
254 list of ciphers, supported by your version of OpenSSL, including
255 ones provided by configured engines.
257 The B<enc> program does not support authenticated encryption modes
258 like CCM and GCM, and will not support such modes in the future.
259 The B<enc> interface by necessity must begin streaming output (e.g.,
260 to standard output when B<-out> is not used) before the authentication
261 tag could be validated, leading to the usage of B<enc> in pipelines
262 that begin processing untrusted data and are not capable of rolling
263 back upon authentication failure. The AEAD modes currently in common
264 use also suffer from catastrophic failure of confidentiality and/or
265 integrity upon reuse of key/iv/nonce, and since B<enc> places the
266 entire burden of key/iv/nonce management upon the user, the risk of
267 exposing AEAD modes is too great to allow. These key/iv/nonce
268 management issues also affect other modes currently exposed in B<enc>,
269 but the failure modes are less extreme in these cases, and the
270 functionality cannot be removed with a stable release branch.
271 For bulk encryption of data, whether using authenticated encryption
272 modes or other modes, L<cms(1)> is recommended, as it provides a
273 standard data format and performs the needed key/iv/nonce management.
278 bf-cbc Blowfish in CBC mode
280 blowfish Alias for bf-cbc
281 bf-cfb Blowfish in CFB mode
282 bf-ecb Blowfish in ECB mode
283 bf-ofb Blowfish in OFB mode
285 cast-cbc CAST in CBC mode
286 cast Alias for cast-cbc
287 cast5-cbc CAST5 in CBC mode
288 cast5-cfb CAST5 in CFB mode
289 cast5-ecb CAST5 in ECB mode
290 cast5-ofb CAST5 in OFB mode
292 chacha20 ChaCha20 algorithm
294 des-cbc DES in CBC mode
295 des Alias for des-cbc
296 des-cfb DES in CFB mode
297 des-ofb DES in OFB mode
298 des-ecb DES in ECB mode
300 des-ede-cbc Two key triple DES EDE in CBC mode
301 des-ede Two key triple DES EDE in ECB mode
302 des-ede-cfb Two key triple DES EDE in CFB mode
303 des-ede-ofb Two key triple DES EDE in OFB mode
305 des-ede3-cbc Three key triple DES EDE in CBC mode
306 des-ede3 Three key triple DES EDE in ECB mode
307 des3 Alias for des-ede3-cbc
308 des-ede3-cfb Three key triple DES EDE CFB mode
309 des-ede3-ofb Three key triple DES EDE in OFB mode
313 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
314 gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
316 idea-cbc IDEA algorithm in CBC mode
317 idea same as idea-cbc
318 idea-cfb IDEA in CFB mode
319 idea-ecb IDEA in ECB mode
320 idea-ofb IDEA in OFB mode
322 rc2-cbc 128 bit RC2 in CBC mode
323 rc2 Alias for rc2-cbc
324 rc2-cfb 128 bit RC2 in CFB mode
325 rc2-ecb 128 bit RC2 in ECB mode
326 rc2-ofb 128 bit RC2 in OFB mode
327 rc2-64-cbc 64 bit RC2 in CBC mode
328 rc2-40-cbc 40 bit RC2 in CBC mode
334 rc5-cbc RC5 cipher in CBC mode
335 rc5 Alias for rc5-cbc
336 rc5-cfb RC5 cipher in CFB mode
337 rc5-ecb RC5 cipher in ECB mode
338 rc5-ofb RC5 cipher in OFB mode
340 seed-cbc SEED cipher in CBC mode
341 seed Alias for seed-cbc
342 seed-cfb SEED cipher in CFB mode
343 seed-ecb SEED cipher in ECB mode
344 seed-ofb SEED cipher in OFB mode
346 sm4-cbc SM4 cipher in CBC mode
347 sm4 Alias for sm4-cbc
348 sm4-cfb SM4 cipher in CFB mode
349 sm4-ctr SM4 cipher in CTR mode
350 sm4-ecb SM4 cipher in ECB mode
351 sm4-ofb SM4 cipher in OFB mode
353 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
354 aes[128|192|256] Alias for aes-[128|192|256]-cbc
355 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
356 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
357 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
358 aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode
359 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
360 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
362 aria-[128|192|256]-cbc 128/192/256 bit ARIA in CBC mode
363 aria[128|192|256] Alias for aria-[128|192|256]-cbc
364 aria-[128|192|256]-cfb 128/192/256 bit ARIA in 128 bit CFB mode
365 aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
366 aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
367 aria-[128|192|256]-ctr 128/192/256 bit ARIA in CTR mode
368 aria-[128|192|256]-ecb 128/192/256 bit ARIA in ECB mode
369 aria-[128|192|256]-ofb 128/192/256 bit ARIA in OFB mode
371 camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
372 camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
373 camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
374 camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
375 camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
376 camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
377 camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
378 camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
382 Just base64 encode a binary file:
384 openssl base64 -in file.bin -out file.b64
388 openssl base64 -d -in file.b64 -out file.bin
390 Encrypt a file using AES-128 using a prompted password
391 and PBKDF2 key derivation:
393 openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
395 Decrypt a file using a supplied password:
397 openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
398 -pass pass:<password>
400 Encrypt a file then base64 encode it (so it can be sent via mail for example)
401 using AES-256 in CTR mode and PBKDF2 key derivation:
403 openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
405 Base64 decode a file then decrypt it using a password supplied in a file:
407 openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
408 -pass file:<passfile>
412 The B<-A> option when used with large files doesn't work properly.
414 The B<enc> program only supports a fixed number of algorithms with
415 certain parameters. So if, for example, you want to use RC2 with a
416 76 bit key or RC4 with an 84 bit key you can't use this program.
420 The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
424 Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
426 Licensed under the Apache License 2.0 (the "License"). You may not use
427 this file except in compliance with the License. You can obtain a copy
428 in the file LICENSE in the source distribution or at
429 L<https://www.openssl.org/source/license.html>.