5 openssl-enc - symmetric cipher routines
9 B<openssl> B<enc>|I<cipher>
23 [B<-kfile> I<filename>]
35 [B<-bufsize> I<number>]
40 [B<-writerand> I<file>]
43 =for openssl ifdef z engine
45 B<openssl> I<cipher> [B<...>]
49 The symmetric cipher commands allow data to be encrypted or decrypted
50 using various block and stream ciphers using keys based on passwords
51 or explicitly provided. Base64 encoding or decoding can also be performed
52 either by itself or in addition to the encryption or decryption.
60 Print out a usage message.
64 List all supported ciphers.
68 Alias of -list to display all supported ciphers.
70 =item B<-in> I<filename>
72 The input filename, standard input by default.
74 =item B<-out> I<filename>
76 The output filename, standard output by default.
80 The password source. For more information about the format of I<arg>
81 see L<openssl(1)/Pass Phrase Options>.
85 Encrypt the input data: this is the default.
89 Decrypt the input data.
93 Base64 process the data. This means that if encryption is taking place
94 the data is base64 encoded after encryption. If decryption is set then
95 the input data is base64 decoded before being decrypted.
103 If the B<-a> option is set then base64 process the data on one line.
105 =item B<-k> I<password>
107 The password to derive the key from. This is for compatibility with previous
108 versions of OpenSSL. Superseded by the B<-pass> argument.
110 =item B<-kfile> I<filename>
112 Read the password to derive the key from the first line of I<filename>.
113 This is for compatibility with previous versions of OpenSSL. Superseded by
114 the B<-pass> argument.
116 =item B<-md> I<digest>
118 Use the specified digest to create the key from the passphrase.
119 The default algorithm is sha-256.
121 =item B<-iter> I<count>
123 Use a given number of iterations on the password in deriving the encryption key.
124 High values increase the time required to brute-force the resulting file.
125 This option enables the use of PBKDF2 algorithm to derive the key.
129 Use PBKDF2 algorithm with default iteration count unless otherwise specified.
133 Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
134 used except for test purposes or compatibility with ancient versions of
139 Use salt (randomly generated or provide with B<-S> option) when
140 encrypting, this is the default.
144 The actual salt to use: this must be represented as a string of hex digits.
148 The actual key to use: this must be represented as a string comprised only
149 of hex digits. If only the key is specified, the IV must additionally specified
150 using the B<-iv> option. When both a key and a password are specified, the
151 key given with the B<-K> option will be used and the IV generated from the
152 password will be taken. It does not make much sense to specify both key
157 The actual IV to use: this must be represented as a string comprised only
158 of hex digits. When only the key is specified using the B<-K> option, the
159 IV must explicitly be defined. When a password is being specified using
160 one of the other options, the IV is generated from this password.
164 Print out the key and IV used.
168 Print out the key and IV used then immediately exit: don't do any encryption
171 =item B<-bufsize> I<number>
173 Set the buffer size for I/O.
177 Disable standard block padding.
181 Debug the BIOs used for I/O.
185 Compress or decompress clear text using zlib before encryption or after
186 decryption. This option exists only if OpenSSL with compiled with zlib
187 or zlib-dynamic option.
191 Use NULL cipher (no encryption or decryption of input).
193 =item B<-rand> I<files>, B<-writerand> I<file>
195 See L<openssl(1)/Random State Options> for more information.
201 The program can be called either as C<openssl I<cipher>> or
202 C<openssl enc -I<cipher>>. The first form doesn't work with
203 engine-provided ciphers, because this form is processed before the
204 configuration file is read and any ENGINEs loaded.
205 Use the L<openssl-list(1)> command to get a list of supported ciphers.
207 Engines which provide entirely new encryption algorithms (such as the ccgost
208 engine which provides gost89 algorithm) should be configured in the
209 configuration file. Engines specified on the command line using -engine
210 options can only be used for hardware-assisted implementations of
211 ciphers which are supported by the OpenSSL core or another engine specified
212 in the configuration file.
214 When the enc command lists supported ciphers, ciphers provided by engines,
215 specified in the configuration files are listed too.
217 A password will be prompted for to derive the key and IV if necessary.
219 The B<-salt> option should B<ALWAYS> be used if the key is being derived
220 from a password unless you want compatibility with previous versions of
223 Without the B<-salt> option it is possible to perform efficient dictionary
224 attacks on the password and to attack stream cipher encrypted data. The reason
225 for this is that without the salt the same password always generates the same
226 encryption key. When the salt is being used the first eight bytes of the
227 encrypted data are reserved for the salt: it is generated at random when
228 encrypting a file and read from the encrypted file when it is decrypted.
230 Some of the ciphers do not have large keys and others have security
231 implications if not used correctly. A beginner is advised to just use
232 a strong block cipher, such as AES, in CBC mode.
234 All the block ciphers normally use PKCS#5 padding, also known as standard
235 block padding. This allows a rudimentary integrity or password check to
236 be performed. However since the chance of random data passing the test
237 is better than 1 in 256 it isn't a very good test.
239 If padding is disabled then the input data must be a multiple of the cipher
242 All RC2 ciphers have the same key and effective key length.
244 Blowfish and RC5 algorithms use a 128 bit key.
246 =head1 SUPPORTED CIPHERS
248 Note that some of these ciphers can be disabled at compile time
249 and some are available only if an appropriate engine is configured
250 in the configuration file. The output when invoking this command
251 with the B<-ciphers> option (that is C<openssl enc -ciphers>) is
252 a list of ciphers, supported by your version of OpenSSL, including
253 ones provided by configured engines.
255 This command does not support authenticated encryption modes
256 like CCM and GCM, and will not support such modes in the future.
257 This is due to having to begin streaming output (e.g., to standard output
258 when B<-out> is not used) before the authentication tag could be validated.
259 When this command is used in a pipeline, the receiveing end will not be
260 able to roll back upon authentication failure. The AEAD modes currently in
261 common use also suffer from catastrophic failure of confidentiality and/or
262 integrity upon reuse of key/iv/nonce, and since B<openssl enc> places the
263 entire burden of key/iv/nonce management upon the user, the risk of
264 exposing AEAD modes is too great to allow. These key/iv/nonce
265 management issues also affect other modes currently exposed in this command,
266 but the failure modes are less extreme in these cases, and the
267 functionality cannot be removed with a stable release branch.
268 For bulk encryption of data, whether using authenticated encryption
269 modes or other modes, L<openssl-cms(1)> is recommended, as it provides a
270 standard data format and performs the needed key/iv/nonce management.
275 bf-cbc Blowfish in CBC mode
277 blowfish Alias for bf-cbc
278 bf-cfb Blowfish in CFB mode
279 bf-ecb Blowfish in ECB mode
280 bf-ofb Blowfish in OFB mode
282 cast-cbc CAST in CBC mode
283 cast Alias for cast-cbc
284 cast5-cbc CAST5 in CBC mode
285 cast5-cfb CAST5 in CFB mode
286 cast5-ecb CAST5 in ECB mode
287 cast5-ofb CAST5 in OFB mode
289 chacha20 ChaCha20 algorithm
291 des-cbc DES in CBC mode
292 des Alias for des-cbc
293 des-cfb DES in CFB mode
294 des-ofb DES in OFB mode
295 des-ecb DES in ECB mode
297 des-ede-cbc Two key triple DES EDE in CBC mode
298 des-ede Two key triple DES EDE in ECB mode
299 des-ede-cfb Two key triple DES EDE in CFB mode
300 des-ede-ofb Two key triple DES EDE in OFB mode
302 des-ede3-cbc Three key triple DES EDE in CBC mode
303 des-ede3 Three key triple DES EDE in ECB mode
304 des3 Alias for des-ede3-cbc
305 des-ede3-cfb Three key triple DES EDE CFB mode
306 des-ede3-ofb Three key triple DES EDE in OFB mode
310 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
311 gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
313 idea-cbc IDEA algorithm in CBC mode
314 idea same as idea-cbc
315 idea-cfb IDEA in CFB mode
316 idea-ecb IDEA in ECB mode
317 idea-ofb IDEA in OFB mode
319 rc2-cbc 128 bit RC2 in CBC mode
320 rc2 Alias for rc2-cbc
321 rc2-cfb 128 bit RC2 in CFB mode
322 rc2-ecb 128 bit RC2 in ECB mode
323 rc2-ofb 128 bit RC2 in OFB mode
324 rc2-64-cbc 64 bit RC2 in CBC mode
325 rc2-40-cbc 40 bit RC2 in CBC mode
331 rc5-cbc RC5 cipher in CBC mode
332 rc5 Alias for rc5-cbc
333 rc5-cfb RC5 cipher in CFB mode
334 rc5-ecb RC5 cipher in ECB mode
335 rc5-ofb RC5 cipher in OFB mode
337 seed-cbc SEED cipher in CBC mode
338 seed Alias for seed-cbc
339 seed-cfb SEED cipher in CFB mode
340 seed-ecb SEED cipher in ECB mode
341 seed-ofb SEED cipher in OFB mode
343 sm4-cbc SM4 cipher in CBC mode
344 sm4 Alias for sm4-cbc
345 sm4-cfb SM4 cipher in CFB mode
346 sm4-ctr SM4 cipher in CTR mode
347 sm4-ecb SM4 cipher in ECB mode
348 sm4-ofb SM4 cipher in OFB mode
350 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
351 aes[128|192|256] Alias for aes-[128|192|256]-cbc
352 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
353 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
354 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
355 aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode
356 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
357 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
359 aria-[128|192|256]-cbc 128/192/256 bit ARIA in CBC mode
360 aria[128|192|256] Alias for aria-[128|192|256]-cbc
361 aria-[128|192|256]-cfb 128/192/256 bit ARIA in 128 bit CFB mode
362 aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
363 aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
364 aria-[128|192|256]-ctr 128/192/256 bit ARIA in CTR mode
365 aria-[128|192|256]-ecb 128/192/256 bit ARIA in ECB mode
366 aria-[128|192|256]-ofb 128/192/256 bit ARIA in OFB mode
368 camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
369 camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
370 camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
371 camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
372 camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
373 camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
374 camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
375 camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
379 Just base64 encode a binary file:
381 openssl base64 -in file.bin -out file.b64
385 openssl base64 -d -in file.b64 -out file.bin
387 Encrypt a file using AES-128 using a prompted password
388 and PBKDF2 key derivation:
390 openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
392 Decrypt a file using a supplied password:
394 openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
395 -pass pass:<password>
397 Encrypt a file then base64 encode it (so it can be sent via mail for example)
398 using AES-256 in CTR mode and PBKDF2 key derivation:
400 openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
402 Base64 decode a file then decrypt it using a password supplied in a file:
404 openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
405 -pass file:<passfile>
409 The B<-A> option when used with large files doesn't work properly.
411 The B<openssl enc> command only supports a fixed number of algorithms with
412 certain parameters. So if, for example, you want to use RC2 with a
413 76 bit key or RC4 with an 84 bit key you can't use this program.
417 The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
419 The B<-list> option was added in OpenSSL 1.1.1e.
421 The B<-ciphers> option was deprecated in OpenSSL 3.0.
425 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
427 Licensed under the Apache License 2.0 (the "License"). You may not use
428 this file except in compliance with the License. You can obtain a copy
429 in the file LICENSE in the source distribution or at
430 L<https://www.openssl.org/source/license.html>.