5 openssl-enc - symmetric cipher routines
9 B<openssl enc -I<cipher>>
41 B<openssl> I<[cipher]> [B<...>]
45 The symmetric cipher commands allow data to be encrypted or decrypted
46 using various block and stream ciphers using keys based on passwords
47 or explicitly provided. Base64 encoding or decoding can also be performed
48 either by itself or in addition to the encryption or decryption.
56 Print out a usage message.
60 List all supported ciphers.
64 The input filename, standard input by default.
66 =item B<-out filename>
68 The output filename, standard output by default.
72 The password source. For more information about the format of B<arg>
73 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
77 Encrypt the input data: this is the default.
81 Decrypt the input data.
85 Base64 process the data. This means that if encryption is taking place
86 the data is base64 encoded after encryption. If decryption is set then
87 the input data is base64 decoded before being decrypted.
95 If the B<-a> option is set then base64 process the data on one line.
99 The password to derive the key from. This is for compatibility with previous
100 versions of OpenSSL. Superseded by the B<-pass> argument.
102 =item B<-kfile filename>
104 Read the password to derive the key from the first line of B<filename>.
105 This is for compatibility with previous versions of OpenSSL. Superseded by
106 the B<-pass> argument.
110 Use the specified digest to create the key from the passphrase.
111 The default algorithm is sha-256.
115 Use a given number of iterations on the password in deriving the encryption key.
116 High values increase the time required to brute-force the resulting file.
117 This option enables the use of PBKDF2 algorithm to derive the key.
121 Use PBKDF2 algorithm with default iteration count unless otherwise specified.
125 Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
126 used except for test purposes or compatibility with ancient versions of
131 Use salt (randomly generated or provide with B<-S> option) when
132 encrypting, this is the default.
136 The actual salt to use: this must be represented as a string of hex digits.
140 The actual key to use: this must be represented as a string comprised only
141 of hex digits. If only the key is specified, the IV must additionally specified
142 using the B<-iv> option. When both a key and a password are specified, the
143 key given with the B<-K> option will be used and the IV generated from the
144 password will be taken. It does not make much sense to specify both key
149 The actual IV to use: this must be represented as a string comprised only
150 of hex digits. When only the key is specified using the B<-K> option, the
151 IV must explicitly be defined. When a password is being specified using
152 one of the other options, the IV is generated from this password.
156 Print out the key and IV used.
160 Print out the key and IV used then immediately exit: don't do any encryption
163 =item B<-bufsize number>
165 Set the buffer size for I/O.
169 Disable standard block padding.
173 Debug the BIOs used for I/O.
177 Compress or decompress clear text using zlib before encryption or after
178 decryption. This option exists only if OpenSSL with compiled with zlib
179 or zlib-dynamic option.
183 Use NULL cipher (no encryption or decryption of input).
185 =item B<-rand file...>
187 A file or files containing random data used to seed the random number
189 Multiple files can be specified separated by an OS-dependent character.
190 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
193 =item [B<-writerand file>]
195 Writes random data to the specified I<file> upon exit.
196 This can be used with a subsequent B<-rand> flag.
202 The program can be called either as B<openssl cipher> or
203 B<openssl enc -cipher>. The first form doesn't work with
204 engine-provided ciphers, because this form is processed before the
205 configuration file is read and any ENGINEs loaded.
206 Use the B<list> command to get a list of supported ciphers.
208 Engines which provide entirely new encryption algorithms (such as the ccgost
209 engine which provides gost89 algorithm) should be configured in the
210 configuration file. Engines specified on the command line using -engine
211 options can only be used for hardware-assisted implementations of
212 ciphers which are supported by the OpenSSL core or another engine specified
213 in the configuration file.
215 When the enc command lists supported ciphers, ciphers provided by engines,
216 specified in the configuration files are listed too.
218 A password will be prompted for to derive the key and IV if necessary.
220 The B<-salt> option should B<ALWAYS> be used if the key is being derived
221 from a password unless you want compatibility with previous versions of
224 Without the B<-salt> option it is possible to perform efficient dictionary
225 attacks on the password and to attack stream cipher encrypted data. The reason
226 for this is that without the salt the same password always generates the same
227 encryption key. When the salt is being used the first eight bytes of the
228 encrypted data are reserved for the salt: it is generated at random when
229 encrypting a file and read from the encrypted file when it is decrypted.
231 Some of the ciphers do not have large keys and others have security
232 implications if not used correctly. A beginner is advised to just use
233 a strong block cipher, such as AES, in CBC mode.
235 All the block ciphers normally use PKCS#5 padding, also known as standard
236 block padding. This allows a rudimentary integrity or password check to
237 be performed. However since the chance of random data passing the test
238 is better than 1 in 256 it isn't a very good test.
240 If padding is disabled then the input data must be a multiple of the cipher
243 All RC2 ciphers have the same key and effective key length.
245 Blowfish and RC5 algorithms use a 128 bit key.
247 =head1 SUPPORTED CIPHERS
249 Note that some of these ciphers can be disabled at compile time
250 and some are available only if an appropriate engine is configured
251 in the configuration file. The output of the B<enc> command run with
252 the B<-ciphers> option (that is B<openssl enc -ciphers>) produces a
253 list of ciphers, supported by your version of OpenSSL, including
254 ones provided by configured engines.
256 The B<enc> program does not support authenticated encryption modes
257 like CCM and GCM, and will not support such modes in the future.
258 The B<enc> interface by necessity must begin streaming output (e.g.,
259 to standard output when B<-out> is not used) before the authentication
260 tag could be validated, leading to the usage of B<enc> in pipelines
261 that begin processing untrusted data and are not capable of rolling
262 back upon authentication failure. The AEAD modes currently in common
263 use also suffer from catastrophic failure of confidentiality and/or
264 integrity upon reuse of key/iv/nonce, and since B<enc> places the
265 entire burden of key/iv/nonce management upon the user, the risk of
266 exposing AEAD modes is too great to allow. These key/iv/nonce
267 management issues also affect other modes currently exposed in B<enc>,
268 but the failure modes are less extreme in these cases, and the
269 functionality cannot be removed with a stable release branch.
270 For bulk encryption of data, whether using authenticated encryption
271 modes or other modes, L<cms(1)> is recommended, as it provides a
272 standard data format and performs the needed key/iv/nonce management.
277 bf-cbc Blowfish in CBC mode
279 blowfish Alias for bf-cbc
280 bf-cfb Blowfish in CFB mode
281 bf-ecb Blowfish in ECB mode
282 bf-ofb Blowfish in OFB mode
284 cast-cbc CAST in CBC mode
285 cast Alias for cast-cbc
286 cast5-cbc CAST5 in CBC mode
287 cast5-cfb CAST5 in CFB mode
288 cast5-ecb CAST5 in ECB mode
289 cast5-ofb CAST5 in OFB mode
291 chacha20 ChaCha20 algorithm
293 des-cbc DES in CBC mode
294 des Alias for des-cbc
295 des-cfb DES in CFB mode
296 des-ofb DES in OFB mode
297 des-ecb DES in ECB mode
299 des-ede-cbc Two key triple DES EDE in CBC mode
300 des-ede Two key triple DES EDE in ECB mode
301 des-ede-cfb Two key triple DES EDE in CFB mode
302 des-ede-ofb Two key triple DES EDE in OFB mode
304 des-ede3-cbc Three key triple DES EDE in CBC mode
305 des-ede3 Three key triple DES EDE in ECB mode
306 des3 Alias for des-ede3-cbc
307 des-ede3-cfb Three key triple DES EDE CFB mode
308 des-ede3-ofb Three key triple DES EDE in OFB mode
312 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
313 gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
315 idea-cbc IDEA algorithm in CBC mode
316 idea same as idea-cbc
317 idea-cfb IDEA in CFB mode
318 idea-ecb IDEA in ECB mode
319 idea-ofb IDEA in OFB mode
321 rc2-cbc 128 bit RC2 in CBC mode
322 rc2 Alias for rc2-cbc
323 rc2-cfb 128 bit RC2 in CFB mode
324 rc2-ecb 128 bit RC2 in ECB mode
325 rc2-ofb 128 bit RC2 in OFB mode
326 rc2-64-cbc 64 bit RC2 in CBC mode
327 rc2-40-cbc 40 bit RC2 in CBC mode
333 rc5-cbc RC5 cipher in CBC mode
334 rc5 Alias for rc5-cbc
335 rc5-cfb RC5 cipher in CFB mode
336 rc5-ecb RC5 cipher in ECB mode
337 rc5-ofb RC5 cipher in OFB mode
339 seed-cbc SEED cipher in CBC mode
340 seed Alias for seed-cbc
341 seed-cfb SEED cipher in CFB mode
342 seed-ecb SEED cipher in ECB mode
343 seed-ofb SEED cipher in OFB mode
345 sm4-cbc SM4 cipher in CBC mode
346 sm4 Alias for sm4-cbc
347 sm4-cfb SM4 cipher in CFB mode
348 sm4-ctr SM4 cipher in CTR mode
349 sm4-ecb SM4 cipher in ECB mode
350 sm4-ofb SM4 cipher in OFB mode
352 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
353 aes[128|192|256] Alias for aes-[128|192|256]-cbc
354 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
355 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
356 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
357 aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode
358 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
359 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
361 aria-[128|192|256]-cbc 128/192/256 bit ARIA in CBC mode
362 aria[128|192|256] Alias for aria-[128|192|256]-cbc
363 aria-[128|192|256]-cfb 128/192/256 bit ARIA in 128 bit CFB mode
364 aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
365 aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
366 aria-[128|192|256]-ctr 128/192/256 bit ARIA in CTR mode
367 aria-[128|192|256]-ecb 128/192/256 bit ARIA in ECB mode
368 aria-[128|192|256]-ofb 128/192/256 bit ARIA in OFB mode
370 camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
371 camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
372 camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
373 camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
374 camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
375 camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
376 camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
377 camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
381 Just base64 encode a binary file:
383 openssl base64 -in file.bin -out file.b64
387 openssl base64 -d -in file.b64 -out file.bin
389 Encrypt a file using AES-128 using a prompted password
390 and PBKDF2 key derivation:
392 openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
394 Decrypt a file using a supplied password:
396 openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
397 -pass pass:<password>
399 Encrypt a file then base64 encode it (so it can be sent via mail for example)
400 using AES-256 in CTR mode and PBKDF2 key derivation:
402 openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
404 Base64 decode a file then decrypt it using a password supplied in a file:
406 openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
407 -pass file:<passfile>
411 The B<-A> option when used with large files doesn't work properly.
413 The B<enc> program only supports a fixed number of algorithms with
414 certain parameters. So if, for example, you want to use RC2 with a
415 76 bit key or RC4 with an 84 bit key you can't use this program.
419 The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
423 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
425 Licensed under the Apache License 2.0 (the "License"). You may not use
426 this file except in compliance with the License. You can obtain a copy
427 in the file LICENSE in the source distribution or at
428 L<https://www.openssl.org/source/license.html>.