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.
63 Print out a usage message.
67 List all supported ciphers.
71 Alias of -list to display all supported ciphers.
73 =item B<-in> I<filename>
75 The input filename, standard input by default.
77 =item B<-out> I<filename>
79 The output filename, standard output by default.
83 The password source. For more information about the format of I<arg>
84 see L<openssl-passphrase-options(1)>.
88 Encrypt the input data: this is the default.
92 Decrypt the input data.
96 Base64 process the data. This means that if encryption is taking place
97 the data is base64 encoded after encryption. If decryption is set then
98 the input data is base64 decoded before being decrypted.
106 If the B<-a> option is set then base64 process the data on one line.
108 =item B<-k> I<password>
110 The password to derive the key from. This is for compatibility with previous
111 versions of OpenSSL. Superseded by the B<-pass> argument.
113 =item B<-kfile> I<filename>
115 Read the password to derive the key from the first line of I<filename>.
116 This is for compatibility with previous versions of OpenSSL. Superseded by
117 the B<-pass> argument.
119 =item B<-md> I<digest>
121 Use the specified digest to create the key from the passphrase.
122 The default algorithm is sha-256.
124 =item B<-iter> I<count>
126 Use a given number of iterations on the password in deriving the encryption key.
127 High values increase the time required to brute-force the resulting file.
128 This option enables the use of PBKDF2 algorithm to derive the key.
132 Use PBKDF2 algorithm with default iteration count unless otherwise specified.
136 Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
137 used except for test purposes or compatibility with ancient versions of
142 Use salt (randomly generated or provide with B<-S> option) when
143 encrypting, this is the default.
147 The actual salt to use: this must be represented as a string of hex digits.
148 If this option is used while encrypting, the same exact value will be needed
149 again during decryption.
153 The actual key to use: this must be represented as a string comprised only
154 of hex digits. If only the key is specified, the IV must additionally specified
155 using the B<-iv> option. When both a key and a password are specified, the
156 key given with the B<-K> option will be used and the IV generated from the
157 password will be taken. It does not make much sense to specify both key
162 The actual IV to use: this must be represented as a string comprised only
163 of hex digits. When only the key is specified using the B<-K> option, the
164 IV must explicitly be defined. When a password is being specified using
165 one of the other options, the IV is generated from this password.
169 Print out the key and IV used.
173 Print out the key and IV used then immediately exit: don't do any encryption
176 =item B<-bufsize> I<number>
178 Set the buffer size for I/O.
182 Disable standard block padding.
186 Verbose print; display some statistics about I/O and buffer sizes.
190 Debug the BIOs used for I/O.
194 Compress or decompress encrypted data using zlib after encryption or before
195 decryption. This option exists only if OpenSSL was compiled with the zlib
196 or zlib-dynamic option.
200 Use NULL cipher (no encryption or decryption of input).
202 {- $OpenSSL::safe::opt_r_item -}
204 {- $OpenSSL::safe::opt_provider_item -}
206 {- $OpenSSL::safe::opt_engine_item -}
212 The program can be called either as C<openssl I<cipher>> or
213 C<openssl enc -I<cipher>>. The first form doesn't work with
214 engine-provided ciphers, because this form is processed before the
215 configuration file is read and any ENGINEs loaded.
216 Use the L<openssl-list(1)> command to get a list of supported ciphers.
218 Engines which provide entirely new encryption algorithms (such as the ccgost
219 engine which provides gost89 algorithm) should be configured in the
220 configuration file. Engines specified on the command line using B<-engine>
221 option can only be used for hardware-assisted implementations of
222 ciphers which are supported by the OpenSSL core or another engine specified
223 in the configuration file.
225 When the enc command lists supported ciphers, ciphers provided by engines,
226 specified in the configuration files are listed too.
228 A password will be prompted for to derive the key and IV if necessary.
230 The B<-salt> option should B<ALWAYS> be used if the key is being derived
231 from a password unless you want compatibility with previous versions of
234 Without the B<-salt> option it is possible to perform efficient dictionary
235 attacks on the password and to attack stream cipher encrypted data. The reason
236 for this is that without the salt the same password always generates the same
239 When the salt is generated at random (that means when encrypting using a
240 passphrase without explicit salt given using B<-S> option), the first bytes
241 of the encrypted data are reserved to store the salt for later decrypting.
243 Some of the ciphers do not have large keys and others have security
244 implications if not used correctly. A beginner is advised to just use
245 a strong block cipher, such as AES, in CBC mode.
247 All the block ciphers normally use PKCS#5 padding, also known as standard
248 block padding. This allows a rudimentary integrity or password check to
249 be performed. However, since the chance of random data passing the test
250 is better than 1 in 256 it isn't a very good test.
252 If padding is disabled then the input data must be a multiple of the cipher
255 All RC2 ciphers have the same key and effective key length.
257 Blowfish and RC5 algorithms use a 128 bit key.
259 =head1 SUPPORTED CIPHERS
261 Note that some of these ciphers can be disabled at compile time
262 and some are available only if an appropriate engine is configured
263 in the configuration file. The output when invoking this command
264 with the B<-list> option (that is C<openssl enc -list>) is
265 a list of ciphers, supported by your version of OpenSSL, including
266 ones provided by configured engines.
268 This command does not support authenticated encryption modes
269 like CCM and GCM, and will not support such modes in the future.
270 This is due to having to begin streaming output (e.g., to standard output
271 when B<-out> is not used) before the authentication tag could be validated.
272 When this command is used in a pipeline, the receiving end will not be
273 able to roll back upon authentication failure. The AEAD modes currently in
274 common use also suffer from catastrophic failure of confidentiality and/or
275 integrity upon reuse of key/iv/nonce, and since B<openssl enc> places the
276 entire burden of key/iv/nonce management upon the user, the risk of
277 exposing AEAD modes is too great to allow. These key/iv/nonce
278 management issues also affect other modes currently exposed in this command,
279 but the failure modes are less extreme in these cases, and the
280 functionality cannot be removed with a stable release branch.
281 For bulk encryption of data, whether using authenticated encryption
282 modes or other modes, L<openssl-cms(1)> is recommended, as it provides a
283 standard data format and performs the needed key/iv/nonce management.
285 When enc is used with key wrapping modes the input data cannot be streamed,
286 meaning it must be processed in a single pass.
287 Consequently, the input data size must be less than
288 the buffer size (-bufsize arg, default to 8*1024 bytes).
289 The '*-wrap' ciphers require the input to be a multiple of 8 bytes long,
290 because no padding is involved.
291 The '*-wrap-pad' ciphers allow any input length.
292 In both cases, no IV is needed. See example below.
297 bf-cbc Blowfish in CBC mode
299 blowfish Alias for bf-cbc
300 bf-cfb Blowfish in CFB mode
301 bf-ecb Blowfish in ECB mode
302 bf-ofb Blowfish in OFB mode
304 cast-cbc CAST in CBC mode
305 cast Alias for cast-cbc
306 cast5-cbc CAST5 in CBC mode
307 cast5-cfb CAST5 in CFB mode
308 cast5-ecb CAST5 in ECB mode
309 cast5-ofb CAST5 in OFB mode
311 chacha20 ChaCha20 algorithm
313 des-cbc DES in CBC mode
314 des Alias for des-cbc
315 des-cfb DES in CFB mode
316 des-ofb DES in OFB mode
317 des-ecb DES in ECB mode
319 des-ede-cbc Two key triple DES EDE in CBC mode
320 des-ede Two key triple DES EDE in ECB mode
321 des-ede-cfb Two key triple DES EDE in CFB mode
322 des-ede-ofb Two key triple DES EDE in OFB mode
324 des-ede3-cbc Three key triple DES EDE in CBC mode
325 des-ede3 Three key triple DES EDE in ECB mode
326 des3 Alias for des-ede3-cbc
327 des-ede3-cfb Three key triple DES EDE CFB mode
328 des-ede3-ofb Three key triple DES EDE in OFB mode
332 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
333 gost89-cnt GOST 28147-89 in CNT mode (provided by ccgost engine)
335 idea-cbc IDEA algorithm in CBC mode
336 idea same as idea-cbc
337 idea-cfb IDEA in CFB mode
338 idea-ecb IDEA in ECB mode
339 idea-ofb IDEA in OFB mode
341 rc2-cbc 128 bit RC2 in CBC mode
342 rc2 Alias for rc2-cbc
343 rc2-cfb 128 bit RC2 in CFB mode
344 rc2-ecb 128 bit RC2 in ECB mode
345 rc2-ofb 128 bit RC2 in OFB mode
346 rc2-64-cbc 64 bit RC2 in CBC mode
347 rc2-40-cbc 40 bit RC2 in CBC mode
353 rc5-cbc RC5 cipher in CBC mode
354 rc5 Alias for rc5-cbc
355 rc5-cfb RC5 cipher in CFB mode
356 rc5-ecb RC5 cipher in ECB mode
357 rc5-ofb RC5 cipher in OFB mode
359 seed-cbc SEED cipher in CBC mode
360 seed Alias for seed-cbc
361 seed-cfb SEED cipher in CFB mode
362 seed-ecb SEED cipher in ECB mode
363 seed-ofb SEED cipher in OFB mode
365 sm4-cbc SM4 cipher in CBC mode
366 sm4 Alias for sm4-cbc
367 sm4-cfb SM4 cipher in CFB mode
368 sm4-ctr SM4 cipher in CTR mode
369 sm4-ecb SM4 cipher in ECB mode
370 sm4-ofb SM4 cipher in OFB mode
372 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
373 aes[128|192|256] Alias for aes-[128|192|256]-cbc
374 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
375 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
376 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
377 aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode
378 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
379 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
381 aes-[128|192|256]-wrap key wrapping using 128/192/256 bit AES
382 aes-[128|192|256]-wrap-pad key wrapping with padding using 128/192/256 bit AES
384 aria-[128|192|256]-cbc 128/192/256 bit ARIA in CBC mode
385 aria[128|192|256] Alias for aria-[128|192|256]-cbc
386 aria-[128|192|256]-cfb 128/192/256 bit ARIA in 128 bit CFB mode
387 aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
388 aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
389 aria-[128|192|256]-ctr 128/192/256 bit ARIA in CTR mode
390 aria-[128|192|256]-ecb 128/192/256 bit ARIA in ECB mode
391 aria-[128|192|256]-ofb 128/192/256 bit ARIA in OFB mode
393 camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
394 camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
395 camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
396 camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
397 camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
398 camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
399 camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
400 camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
404 Just base64 encode a binary file:
406 openssl base64 -in file.bin -out file.b64
410 openssl base64 -d -in file.b64 -out file.bin
412 Encrypt a file using AES-128 using a prompted password
413 and PBKDF2 key derivation:
415 openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
417 Decrypt a file using a supplied password:
419 openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
420 -pass pass:<password>
422 Encrypt a file then base64 encode it (so it can be sent via mail for example)
423 using AES-256 in CTR mode and PBKDF2 key derivation:
425 openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
427 Base64 decode a file then decrypt it using a password supplied in a file:
429 openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
430 -pass file:<passfile>
434 openssl enc -e -a -id-aes128-wrap-pad -K 000102030405060708090A0B0C0D0E0F -in file.bin
436 openssl aes128-wrap-pad -e -a -K 000102030405060708090A0B0C0D0E0F -in file.bin
440 The B<-A> option when used with large files doesn't work properly.
442 The B<openssl enc> command only supports a fixed number of algorithms with
443 certain parameters. So if, for example, you want to use RC2 with a
444 76 bit key or RC4 with an 84 bit key you can't use this program.
448 The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
450 The B<-list> option was added in OpenSSL 1.1.1e.
452 The B<-ciphers> and B<-engine> options were deprecated in OpenSSL 3.0.
456 Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved.
458 Licensed under the Apache License 2.0 (the "License"). You may not use
459 this file except in compliance with the License. You can obtain a copy
460 in the file LICENSE in the source distribution or at
461 L<https://www.openssl.org/source/license.html>.