2 {- OpenSSL::safe::output_do_not_edit_headers(); -}
6 openssl-enc - symmetric cipher routines
10 B<openssl> B<enc>|I<cipher>
24 [B<-kfile> I<filename>]
36 [B<-bufsize> I<number>]
41 {- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_r_synopsis -}
42 {- $OpenSSL::safe::opt_provider_synopsis -}
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.
67 Alias of -list to display all supported ciphers.
69 =item B<-in> I<filename>
71 The input filename, standard input by default.
73 =item B<-out> I<filename>
75 The output filename, standard output by default.
79 The password source. For more information about the format of I<arg>
80 see L<openssl-passphrase-options(1)>.
84 Encrypt the input data: this is the default.
88 Decrypt the input data.
92 Base64 process the data. This means that if encryption is taking place
93 the data is base64 encoded after encryption. If decryption is set then
94 the input data is base64 decoded before being decrypted.
102 If the B<-a> option is set then base64 process the data on one line.
104 =item B<-k> I<password>
106 The password to derive the key from. This is for compatibility with previous
107 versions of OpenSSL. Superseded by the B<-pass> argument.
109 =item B<-kfile> I<filename>
111 Read the password to derive the key from the first line of I<filename>.
112 This is for compatibility with previous versions of OpenSSL. Superseded by
113 the B<-pass> argument.
115 =item B<-md> I<digest>
117 Use the specified digest to create the key from the passphrase.
118 The default algorithm is sha-256.
120 =item B<-iter> I<count>
122 Use a given number of iterations on the password in deriving the encryption key.
123 High values increase the time required to brute-force the resulting file.
124 This option enables the use of PBKDF2 algorithm to derive the key.
128 Use PBKDF2 algorithm with default iteration count unless otherwise specified.
132 Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
133 used except for test purposes or compatibility with ancient versions of
138 Use salt (randomly generated or provide with B<-S> option) when
139 encrypting, this is the default.
143 The actual salt to use: this must be represented as a string of hex digits.
144 If this option is used while encrypting, the same exact value will be needed
145 again during decryption.
149 The actual key to use: this must be represented as a string comprised only
150 of hex digits. If only the key is specified, the IV must additionally specified
151 using the B<-iv> option. When both a key and a password are specified, the
152 key given with the B<-K> option will be used and the IV generated from the
153 password will be taken. It does not make much sense to specify both key
158 The actual IV to use: this must be represented as a string comprised only
159 of hex digits. When only the key is specified using the B<-K> option, the
160 IV must explicitly be defined. When a password is being specified using
161 one of the other options, the IV is generated from this password.
165 Print out the key and IV used.
169 Print out the key and IV used then immediately exit: don't do any encryption
172 =item B<-bufsize> I<number>
174 Set the buffer size for I/O.
178 Disable standard block padding.
182 Verbose print; display some statistics about I/O and buffer sizes.
186 Debug the BIOs used for I/O.
190 Compress or decompress encrypted data using zlib after encryption or before
191 decryption. This option exists only if OpenSSL was compiled with the zlib
192 or zlib-dynamic option.
196 Use NULL cipher (no encryption or decryption of input).
198 {- $OpenSSL::safe::opt_r_item -}
200 {- $OpenSSL::safe::opt_provider_item -}
202 {- $OpenSSL::safe::opt_engine_item -}
208 The program can be called either as C<openssl I<cipher>> or
209 C<openssl enc -I<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 L<openssl-list(1)> 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 B<-engine>
217 option 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
235 When the salt is generated at random (that means when encrypting using a
236 passphrase without explicit salt given using B<-S> option), the first bytes
237 of the encrypted data are reserved to store the salt for later decrypting.
239 Some of the ciphers do not have large keys and others have security
240 implications if not used correctly. A beginner is advised to just use
241 a strong block cipher, such as AES, in CBC mode.
243 All the block ciphers normally use PKCS#5 padding, also known as standard
244 block padding. This allows a rudimentary integrity or password check to
245 be performed. However, since the chance of random data passing the test
246 is better than 1 in 256 it isn't a very good test.
248 If padding is disabled then the input data must be a multiple of the cipher
251 All RC2 ciphers have the same key and effective key length.
253 Blowfish and RC5 algorithms use a 128 bit key.
255 =head1 SUPPORTED CIPHERS
257 Note that some of these ciphers can be disabled at compile time
258 and some are available only if an appropriate engine is configured
259 in the configuration file. The output when invoking this command
260 with the B<-list> option (that is C<openssl enc -list>) is
261 a list of ciphers, supported by your version of OpenSSL, including
262 ones provided by configured engines.
264 This command does not support authenticated encryption modes
265 like CCM and GCM, and will not support such modes in the future.
266 This is due to having to begin streaming output (e.g., to standard output
267 when B<-out> is not used) before the authentication tag could be validated.
268 When this command is used in a pipeline, the receiving end will not be
269 able to roll back upon authentication failure. The AEAD modes currently in
270 common use also suffer from catastrophic failure of confidentiality and/or
271 integrity upon reuse of key/iv/nonce, and since B<openssl enc> places the
272 entire burden of key/iv/nonce management upon the user, the risk of
273 exposing AEAD modes is too great to allow. These key/iv/nonce
274 management issues also affect other modes currently exposed in this command,
275 but the failure modes are less extreme in these cases, and the
276 functionality cannot be removed with a stable release branch.
277 For bulk encryption of data, whether using authenticated encryption
278 modes or other modes, L<openssl-cms(1)> is recommended, as it provides a
279 standard data format and performs the needed key/iv/nonce management.
284 bf-cbc Blowfish in CBC mode
286 blowfish Alias for bf-cbc
287 bf-cfb Blowfish in CFB mode
288 bf-ecb Blowfish in ECB mode
289 bf-ofb Blowfish in OFB mode
291 cast-cbc CAST in CBC mode
292 cast Alias for cast-cbc
293 cast5-cbc CAST5 in CBC mode
294 cast5-cfb CAST5 in CFB mode
295 cast5-ecb CAST5 in ECB mode
296 cast5-ofb CAST5 in OFB mode
298 chacha20 ChaCha20 algorithm
300 des-cbc DES in CBC mode
301 des Alias for des-cbc
302 des-cfb DES in CFB mode
303 des-ofb DES in OFB mode
304 des-ecb DES in ECB mode
306 des-ede-cbc Two key triple DES EDE in CBC mode
307 des-ede Two key triple DES EDE in ECB mode
308 des-ede-cfb Two key triple DES EDE in CFB mode
309 des-ede-ofb Two key triple DES EDE in OFB mode
311 des-ede3-cbc Three key triple DES EDE in CBC mode
312 des-ede3 Three key triple DES EDE in ECB mode
313 des3 Alias for des-ede3-cbc
314 des-ede3-cfb Three key triple DES EDE CFB mode
315 des-ede3-ofb Three key triple DES EDE in OFB mode
319 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
320 gost89-cnt GOST 28147-89 in CNT mode (provided by ccgost engine)
322 idea-cbc IDEA algorithm in CBC mode
323 idea same as idea-cbc
324 idea-cfb IDEA in CFB mode
325 idea-ecb IDEA in ECB mode
326 idea-ofb IDEA in OFB mode
328 rc2-cbc 128 bit RC2 in CBC mode
329 rc2 Alias for rc2-cbc
330 rc2-cfb 128 bit RC2 in CFB mode
331 rc2-ecb 128 bit RC2 in ECB mode
332 rc2-ofb 128 bit RC2 in OFB mode
333 rc2-64-cbc 64 bit RC2 in CBC mode
334 rc2-40-cbc 40 bit RC2 in CBC mode
340 rc5-cbc RC5 cipher in CBC mode
341 rc5 Alias for rc5-cbc
342 rc5-cfb RC5 cipher in CFB mode
343 rc5-ecb RC5 cipher in ECB mode
344 rc5-ofb RC5 cipher in OFB mode
346 seed-cbc SEED cipher in CBC mode
347 seed Alias for seed-cbc
348 seed-cfb SEED cipher in CFB mode
349 seed-ecb SEED cipher in ECB mode
350 seed-ofb SEED cipher in OFB mode
352 sm4-cbc SM4 cipher in CBC mode
353 sm4 Alias for sm4-cbc
354 sm4-cfb SM4 cipher in CFB mode
355 sm4-ctr SM4 cipher in CTR mode
356 sm4-ecb SM4 cipher in ECB mode
357 sm4-ofb SM4 cipher in OFB mode
359 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
360 aes[128|192|256] Alias for aes-[128|192|256]-cbc
361 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
362 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
363 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
364 aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode
365 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
366 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
368 aria-[128|192|256]-cbc 128/192/256 bit ARIA in CBC mode
369 aria[128|192|256] Alias for aria-[128|192|256]-cbc
370 aria-[128|192|256]-cfb 128/192/256 bit ARIA in 128 bit CFB mode
371 aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
372 aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
373 aria-[128|192|256]-ctr 128/192/256 bit ARIA in CTR mode
374 aria-[128|192|256]-ecb 128/192/256 bit ARIA in ECB mode
375 aria-[128|192|256]-ofb 128/192/256 bit ARIA in OFB mode
377 camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
378 camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
379 camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
380 camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
381 camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
382 camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
383 camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
384 camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
388 Just base64 encode a binary file:
390 openssl base64 -in file.bin -out file.b64
394 openssl base64 -d -in file.b64 -out file.bin
396 Encrypt a file using AES-128 using a prompted password
397 and PBKDF2 key derivation:
399 openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
401 Decrypt a file using a supplied password:
403 openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
404 -pass pass:<password>
406 Encrypt a file then base64 encode it (so it can be sent via mail for example)
407 using AES-256 in CTR mode and PBKDF2 key derivation:
409 openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
411 Base64 decode a file then decrypt it using a password supplied in a file:
413 openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
414 -pass file:<passfile>
418 The B<-A> option when used with large files doesn't work properly.
420 The B<openssl enc> command only supports a fixed number of algorithms with
421 certain parameters. So if, for example, you want to use RC2 with a
422 76 bit key or RC4 with an 84 bit key you can't use this program.
426 The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
428 The B<-list> option was added in OpenSSL 1.1.1e.
430 The B<-ciphers> and B<-engine> options were deprecated in OpenSSL 3.0.
434 Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
436 Licensed under the Apache License 2.0 (the "License"). You may not use
437 this file except in compliance with the License. You can obtain a copy
438 in the file LICENSE in the source distribution or at
439 L<https://www.openssl.org/source/license.html>.