6 enc - symmetric cipher routines
10 B<openssl enc -I<cipher>>
40 B<openssl> I<[cipher]> [B<...>]
44 The symmetric cipher commands allow data to be encrypted or decrypted
45 using various block and stream ciphers using keys based on passwords
46 or explicitly provided. Base64 encoding or decoding can also be performed
47 either by itself or in addition to the encryption or decryption.
55 Print out a usage message.
59 List all supported ciphers.
63 The input filename, standard input by default.
65 =item B<-out filename>
67 The output filename, standard output by default.
71 The password source. For more information about the format of B<arg>
72 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
76 Encrypt the input data: this is the default.
80 Decrypt the input data.
84 Base64 process the data. This means that if encryption is taking place
85 the data is base64 encoded after encryption. If decryption is set then
86 the input data is base64 decoded before being decrypted.
94 If the B<-a> option is set then base64 process the data on one line.
98 The password to derive the key from. This is for compatibility with previous
99 versions of OpenSSL. Superseded by the B<-pass> argument.
101 =item B<-kfile filename>
103 Read the password to derive the key from the first line of B<filename>.
104 This is for compatibility with previous versions of OpenSSL. Superseded by
105 the B<-pass> argument.
109 Use the specified digest to create the key from the passphrase.
110 The default algorithm is sha-256.
114 Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
115 used except for test purposes or compatibility with ancient versions of
120 Use salt (randomly generated or provide with B<-S> option) when
121 encrypting, this is the default.
125 The actual salt to use: this must be represented as a string of hex digits.
129 The actual key to use: this must be represented as a string comprised only
130 of hex digits. If only the key is specified, the IV must additionally specified
131 using the B<-iv> option. When both a key and a password are specified, the
132 key given with the B<-K> option will be used and the IV generated from the
133 password will be taken. It does not make much sense to specify both key
138 The actual IV to use: this must be represented as a string comprised only
139 of hex digits. When only the key is specified using the B<-K> option, the
140 IV must explicitly be defined. When a password is being specified using
141 one of the other options, the IV is generated from this password.
145 Print out the key and IV used.
149 Print out the key and IV used then immediately exit: don't do any encryption
152 =item B<-bufsize number>
154 Set the buffer size for I/O.
158 Disable standard block padding.
162 Debug the BIOs used for I/O.
166 Compress or decompress clear text using zlib before encryption or after
167 decryption. This option exists only if OpenSSL with compiled with zlib
168 or zlib-dynamic option.
172 Use NULL cipher (no encryption or decryption of input).
174 =item B<-rand file...>
176 A file or files containing random data used to seed the random number
178 Multiple files can be specified separated by an OS-dependent character.
179 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
182 =item [B<-writerand file>]
184 Writes random data to the specified I<file> upon exit.
185 This can be used with a subsequent B<-rand> flag.
191 The program can be called either as B<openssl cipher> or
192 B<openssl enc -cipher>. The first form doesn't work with
193 engine-provided ciphers, because this form is processed before the
194 configuration file is read and any ENGINEs loaded.
195 Use the B<list> command to get a list of supported ciphers.
197 Engines which provide entirely new encryption algorithms (such as the ccgost
198 engine which provides gost89 algorithm) should be configured in the
199 configuration file. Engines specified on the command line using -engine
200 options can only be used for hardware-assisted implementations of
201 ciphers which are supported by the OpenSSL core or another engine specified
202 in the configuration file.
204 When the enc command lists supported ciphers, ciphers provided by engines,
205 specified in the configuration files are listed too.
207 A password will be prompted for to derive the key and IV if necessary.
209 The B<-salt> option should B<ALWAYS> be used if the key is being derived
210 from a password unless you want compatibility with previous versions of
213 Without the B<-salt> option it is possible to perform efficient dictionary
214 attacks on the password and to attack stream cipher encrypted data. The reason
215 for this is that without the salt the same password always generates the same
216 encryption key. When the salt is being used the first eight bytes of the
217 encrypted data are reserved for the salt: it is generated at random when
218 encrypting a file and read from the encrypted file when it is decrypted.
220 Some of the ciphers do not have large keys and others have security
221 implications if not used correctly. A beginner is advised to just use
222 a strong block cipher, such as AES, in CBC mode.
224 All the block ciphers normally use PKCS#5 padding, also known as standard
225 block padding. This allows a rudimentary integrity or password check to
226 be performed. However since the chance of random data passing the test
227 is better than 1 in 256 it isn't a very good test.
229 If padding is disabled then the input data must be a multiple of the cipher
232 All RC2 ciphers have the same key and effective key length.
234 Blowfish and RC5 algorithms use a 128 bit key.
236 =head1 SUPPORTED CIPHERS
238 Note that some of these ciphers can be disabled at compile time
239 and some are available only if an appropriate engine is configured
240 in the configuration file. The output of the B<enc> command run with
241 the B<-ciphers> option (that is B<openssl enc -ciphers>) produces a
242 list of ciphers, supported by your version of OpenSSL, including
243 ones provided by configured engines.
245 The B<enc> program does not support authenticated encryption modes
246 like CCM and GCM, and will not support such modes in the future.
247 The B<enc> interface by necessity must begin streaming output (e.g.,
248 to standard output when B<-out> is not used before the authentication
249 tag could be validated, leading to the usage of B<enc> in pipelines
250 that begin processing untrusted data and are not capable of rolling
251 back upon authentication failure. The AEAD modes currently in common
252 use also suffer from catastrophic failure of confidentiality and/or
253 integrity upon reuse of key/iv/nonce, and since B<enc> places the
254 entire burden of key/iv/nonce management upon the user, the risk of
255 exposing AEAD modes is too great to allow. These key/iv/nonce
256 management issues also affect other modes currently exposed in B<enc>,
257 but the failure modes are less extreme in these cases, and the
258 functionality cannot be removed with a stable release branch.
259 For bulk encryption of data, whether using authenticated encryption
260 modes or other modes, L<cms(1)> is recommended, as it provides a
261 standard data format and performs the needed key/iv/nonce management.
266 bf-cbc Blowfish in CBC mode
268 bf-cfb Blowfish in CFB mode
269 bf-ecb Blowfish in ECB mode
270 bf-ofb Blowfish in OFB mode
272 cast-cbc CAST in CBC mode
273 cast Alias for cast-cbc
274 cast5-cbc CAST5 in CBC mode
275 cast5-cfb CAST5 in CFB mode
276 cast5-ecb CAST5 in ECB mode
277 cast5-ofb CAST5 in OFB mode
279 des-cbc DES in CBC mode
280 des Alias for des-cbc
281 des-cfb DES in CFB mode
282 des-ofb DES in OFB mode
283 des-ecb DES in ECB mode
285 des-ede-cbc Two key triple DES EDE in CBC mode
286 des-ede Two key triple DES EDE in ECB mode
287 des-ede-cfb Two key triple DES EDE in CFB mode
288 des-ede-ofb Two key triple DES EDE in OFB mode
290 des-ede3-cbc Three key triple DES EDE in CBC mode
291 des-ede3 Three key triple DES EDE in ECB mode
292 des3 Alias for des-ede3-cbc
293 des-ede3-cfb Three key triple DES EDE CFB mode
294 des-ede3-ofb Three key triple DES EDE in OFB mode
298 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
299 gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
301 idea-cbc IDEA algorithm in CBC mode
302 idea same as idea-cbc
303 idea-cfb IDEA in CFB mode
304 idea-ecb IDEA in ECB mode
305 idea-ofb IDEA in OFB mode
307 rc2-cbc 128 bit RC2 in CBC mode
308 rc2 Alias for rc2-cbc
309 rc2-cfb 128 bit RC2 in CFB mode
310 rc2-ecb 128 bit RC2 in ECB mode
311 rc2-ofb 128 bit RC2 in OFB mode
312 rc2-64-cbc 64 bit RC2 in CBC mode
313 rc2-40-cbc 40 bit RC2 in CBC mode
319 rc5-cbc RC5 cipher in CBC mode
320 rc5 Alias for rc5-cbc
321 rc5-cfb RC5 cipher in CFB mode
322 rc5-ecb RC5 cipher in ECB mode
323 rc5-ofb RC5 cipher in OFB mode
325 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
326 aes[128|192|256] Alias for aes-[128|192|256]-cbc
327 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
328 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
329 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
330 aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode
331 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
332 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
334 camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
335 camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
336 camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
337 camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
338 camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
339 camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
340 camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
341 camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
345 Just base64 encode a binary file:
347 openssl base64 -in file.bin -out file.b64
351 openssl base64 -d -in file.b64 -out file.bin
353 Encrypt a file using triple DES in CBC mode using a prompted password:
355 openssl des3 -salt -in file.txt -out file.des3
357 Decrypt a file using a supplied password:
359 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
361 Encrypt a file then base64 encode it (so it can be sent via mail for example)
362 using Blowfish in CBC mode:
364 openssl bf -a -salt -in file.txt -out file.bf
366 Base64 decode a file then decrypt it:
368 openssl bf -d -salt -a -in file.bf -out file.txt
370 Decrypt some data using a supplied 40 bit RC4 key:
372 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
376 The B<-A> option when used with large files doesn't work properly.
378 There should be an option to allow an iteration count to be included.
380 The B<enc> program only supports a fixed number of algorithms with
381 certain parameters. So if, for example, you want to use RC2 with a
382 76 bit key or RC4 with an 84 bit key you can't use this program.
386 The default digest was changed from MD5 to SHA256 in Openssl 1.1.0.
390 Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
392 Licensed under the OpenSSL license (the "License"). You may not use
393 this file except in compliance with the License. You can obtain a copy
394 in the file LICENSE in the source distribution or at
395 L<https://www.openssl.org/source/license.html>.