5 openssl-enc - symmetric cipher routines
9 B<openssl> B<enc>|I<cipher>
22 [B<-kfile> I<filename>]
34 [B<-bufsize> I<number>]
39 [B<-writerand> I<file>]
42 =for openssl ifdef z engine
44 B<openssl> I<cipher> [B<...>]
48 The symmetric cipher commands allow data to be encrypted or decrypted
49 using various block and stream ciphers using keys based on passwords
50 or explicitly provided. Base64 encoding or decoding can also be performed
51 either by itself or in addition to the encryption or decryption.
59 Print out a usage message.
63 List all supported ciphers.
65 =item B<-in> I<filename>
67 The input filename, standard input by default.
69 =item B<-out> I<filename>
71 The output filename, standard output by default.
75 The password source. For more information about the format of I<arg>
76 see L<openssl(1)/Pass Phrase Options>.
80 Encrypt the input data: this is the default.
84 Decrypt the input data.
88 Base64 process the data. This means that if encryption is taking place
89 the data is base64 encoded after encryption. If decryption is set then
90 the input data is base64 decoded before being decrypted.
98 If the B<-a> option is set then base64 process the data on one line.
100 =item B<-k> I<password>
102 The password to derive the key from. This is for compatibility with previous
103 versions of OpenSSL. Superseded by the B<-pass> argument.
105 =item B<-kfile> I<filename>
107 Read the password to derive the key from the first line of I<filename>.
108 This is for compatibility with previous versions of OpenSSL. Superseded by
109 the B<-pass> argument.
111 =item B<-md> I<digest>
113 Use the specified digest to create the key from the passphrase.
114 The default algorithm is sha-256.
116 =item B<-iter> I<count>
118 Use a given number of iterations on the password in deriving the encryption key.
119 High values increase the time required to brute-force the resulting file.
120 This option enables the use of PBKDF2 algorithm to derive the key.
124 Use PBKDF2 algorithm with default iteration count unless otherwise specified.
128 Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
129 used except for test purposes or compatibility with ancient versions of
134 Use salt (randomly generated or provide with B<-S> option) when
135 encrypting, this is the default.
139 The actual salt to use: this must be represented as a string of hex digits.
143 The actual key to use: this must be represented as a string comprised only
144 of hex digits. If only the key is specified, the IV must additionally specified
145 using the B<-iv> option. When both a key and a password are specified, the
146 key given with the B<-K> option will be used and the IV generated from the
147 password will be taken. It does not make much sense to specify both key
152 The actual IV to use: this must be represented as a string comprised only
153 of hex digits. When only the key is specified using the B<-K> option, the
154 IV must explicitly be defined. When a password is being specified using
155 one of the other options, the IV is generated from this password.
159 Print out the key and IV used.
163 Print out the key and IV used then immediately exit: don't do any encryption
166 =item B<-bufsize> I<number>
168 Set the buffer size for I/O.
172 Disable standard block padding.
176 Debug the BIOs used for I/O.
180 Compress or decompress clear text using zlib before encryption or after
181 decryption. This option exists only if OpenSSL with compiled with zlib
182 or zlib-dynamic option.
186 Use NULL cipher (no encryption or decryption of input).
188 =item B<-rand> I<files>, B<-writerand> I<file>
190 See L<openssl(1)/Random State Options> for more information.
196 The program can be called either as C<openssl I<cipher>> or
197 C<openssl enc -I<cipher>>. The first form doesn't work with
198 engine-provided ciphers, because this form is processed before the
199 configuration file is read and any ENGINEs loaded.
200 Use the L<openssl-list(1)> command to get a list of supported ciphers.
202 Engines which provide entirely new encryption algorithms (such as the ccgost
203 engine which provides gost89 algorithm) should be configured in the
204 configuration file. Engines specified on the command line using -engine
205 options can only be used for hardware-assisted implementations of
206 ciphers which are supported by the OpenSSL core or another engine specified
207 in the configuration file.
209 When the enc command lists supported ciphers, ciphers provided by engines,
210 specified in the configuration files are listed too.
212 A password will be prompted for to derive the key and IV if necessary.
214 The B<-salt> option should B<ALWAYS> be used if the key is being derived
215 from a password unless you want compatibility with previous versions of
218 Without the B<-salt> option it is possible to perform efficient dictionary
219 attacks on the password and to attack stream cipher encrypted data. The reason
220 for this is that without the salt the same password always generates the same
221 encryption key. When the salt is being used the first eight bytes of the
222 encrypted data are reserved for the salt: it is generated at random when
223 encrypting a file and read from the encrypted file when it is decrypted.
225 Some of the ciphers do not have large keys and others have security
226 implications if not used correctly. A beginner is advised to just use
227 a strong block cipher, such as AES, in CBC mode.
229 All the block ciphers normally use PKCS#5 padding, also known as standard
230 block padding. This allows a rudimentary integrity or password check to
231 be performed. However since the chance of random data passing the test
232 is better than 1 in 256 it isn't a very good test.
234 If padding is disabled then the input data must be a multiple of the cipher
237 All RC2 ciphers have the same key and effective key length.
239 Blowfish and RC5 algorithms use a 128 bit key.
241 =head1 SUPPORTED CIPHERS
243 Note that some of these ciphers can be disabled at compile time
244 and some are available only if an appropriate engine is configured
245 in the configuration file. The output when invoking this command
246 with the B<-ciphers> option (that is C<openssl enc -ciphers>) is
247 a list of ciphers, supported by your version of OpenSSL, including
248 ones provided by configured engines.
250 This command does not support authenticated encryption modes
251 like CCM and GCM, and will not support such modes in the future.
252 This is due to having to begin streaming output (e.g., to standard output
253 when B<-out> is not used) before the authentication tag could be validated.
254 When this command is used in a pipeline, the receiveing end will not be
255 able to roll back upon authentication failure. The AEAD modes currently in
256 common use also suffer from catastrophic failure of confidentiality and/or
257 integrity upon reuse of key/iv/nonce, and since B<openssl enc> places the
258 entire burden of key/iv/nonce management upon the user, the risk of
259 exposing AEAD modes is too great to allow. These key/iv/nonce
260 management issues also affect other modes currently exposed in this command,
261 but the failure modes are less extreme in these cases, and the
262 functionality cannot be removed with a stable release branch.
263 For bulk encryption of data, whether using authenticated encryption
264 modes or other modes, L<openssl-cms(1)> is recommended, as it provides a
265 standard data format and performs the needed key/iv/nonce management.
270 bf-cbc Blowfish in CBC mode
272 blowfish Alias for bf-cbc
273 bf-cfb Blowfish in CFB mode
274 bf-ecb Blowfish in ECB mode
275 bf-ofb Blowfish in OFB mode
277 cast-cbc CAST in CBC mode
278 cast Alias for cast-cbc
279 cast5-cbc CAST5 in CBC mode
280 cast5-cfb CAST5 in CFB mode
281 cast5-ecb CAST5 in ECB mode
282 cast5-ofb CAST5 in OFB mode
284 chacha20 ChaCha20 algorithm
286 des-cbc DES in CBC mode
287 des Alias for des-cbc
288 des-cfb DES in CFB mode
289 des-ofb DES in OFB mode
290 des-ecb DES in ECB mode
292 des-ede-cbc Two key triple DES EDE in CBC mode
293 des-ede Two key triple DES EDE in ECB mode
294 des-ede-cfb Two key triple DES EDE in CFB mode
295 des-ede-ofb Two key triple DES EDE in OFB mode
297 des-ede3-cbc Three key triple DES EDE in CBC mode
298 des-ede3 Three key triple DES EDE in ECB mode
299 des3 Alias for des-ede3-cbc
300 des-ede3-cfb Three key triple DES EDE CFB mode
301 des-ede3-ofb Three key triple DES EDE in OFB mode
305 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
306 gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
308 idea-cbc IDEA algorithm in CBC mode
309 idea same as idea-cbc
310 idea-cfb IDEA in CFB mode
311 idea-ecb IDEA in ECB mode
312 idea-ofb IDEA in OFB mode
314 rc2-cbc 128 bit RC2 in CBC mode
315 rc2 Alias for rc2-cbc
316 rc2-cfb 128 bit RC2 in CFB mode
317 rc2-ecb 128 bit RC2 in ECB mode
318 rc2-ofb 128 bit RC2 in OFB mode
319 rc2-64-cbc 64 bit RC2 in CBC mode
320 rc2-40-cbc 40 bit RC2 in CBC mode
326 rc5-cbc RC5 cipher in CBC mode
327 rc5 Alias for rc5-cbc
328 rc5-cfb RC5 cipher in CFB mode
329 rc5-ecb RC5 cipher in ECB mode
330 rc5-ofb RC5 cipher in OFB mode
332 seed-cbc SEED cipher in CBC mode
333 seed Alias for seed-cbc
334 seed-cfb SEED cipher in CFB mode
335 seed-ecb SEED cipher in ECB mode
336 seed-ofb SEED cipher in OFB mode
338 sm4-cbc SM4 cipher in CBC mode
339 sm4 Alias for sm4-cbc
340 sm4-cfb SM4 cipher in CFB mode
341 sm4-ctr SM4 cipher in CTR mode
342 sm4-ecb SM4 cipher in ECB mode
343 sm4-ofb SM4 cipher in OFB mode
345 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
346 aes[128|192|256] Alias for aes-[128|192|256]-cbc
347 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
348 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
349 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
350 aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode
351 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
352 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
354 aria-[128|192|256]-cbc 128/192/256 bit ARIA in CBC mode
355 aria[128|192|256] Alias for aria-[128|192|256]-cbc
356 aria-[128|192|256]-cfb 128/192/256 bit ARIA in 128 bit CFB mode
357 aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
358 aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
359 aria-[128|192|256]-ctr 128/192/256 bit ARIA in CTR mode
360 aria-[128|192|256]-ecb 128/192/256 bit ARIA in ECB mode
361 aria-[128|192|256]-ofb 128/192/256 bit ARIA in OFB mode
363 camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
364 camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
365 camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
366 camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
367 camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
368 camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
369 camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
370 camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
374 Just base64 encode a binary file:
376 openssl base64 -in file.bin -out file.b64
380 openssl base64 -d -in file.b64 -out file.bin
382 Encrypt a file using AES-128 using a prompted password
383 and PBKDF2 key derivation:
385 openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
387 Decrypt a file using a supplied password:
389 openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
390 -pass pass:<password>
392 Encrypt a file then base64 encode it (so it can be sent via mail for example)
393 using AES-256 in CTR mode and PBKDF2 key derivation:
395 openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
397 Base64 decode a file then decrypt it using a password supplied in a file:
399 openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
400 -pass file:<passfile>
404 The B<-A> option when used with large files doesn't work properly.
406 The B<openssl enc> command only supports a fixed number of algorithms with
407 certain parameters. So if, for example, you want to use RC2 with a
408 76 bit key or RC4 with an 84 bit key you can't use this program.
412 The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
416 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
418 Licensed under the Apache License 2.0 (the "License"). You may not use
419 this file except in compliance with the License. You can obtain a copy
420 in the file LICENSE in the source distribution or at
421 L<https://www.openssl.org/source/license.html>.