1OPENSSL-ENC(1ossl)                  OpenSSL                 OPENSSL-ENC(1ossl)
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NAME

6       openssl-enc - symmetric cipher routines
7

SYNOPSIS

9       openssl enc|cipher [-cipher] [-help] [-list] [-ciphers] [-in filename]
10       [-out filename] [-pass arg] [-e] [-d] [-a] [-base64] [-A] [-k password]
11       [-kfile filename] [-K key] [-iv IV] [-S salt] [-salt] [-nosalt] [-z]
12       [-md digest] [-iter count] [-pbkdf2] [-p] [-P] [-bufsize number]
13       [-nopad] [-v] [-debug] [-none] [-engine id] [-rand files] [-writerand
14       file] [-provider name] [-provider-path path] [-propquery propq]
15
16       openssl cipher [...]
17

DESCRIPTION

19       The symmetric cipher commands allow data to be encrypted or decrypted
20       using various block and stream ciphers using keys based on passwords or
21       explicitly provided. Base64 encoding or decoding can also be performed
22       either by itself or in addition to the encryption or decryption.
23

OPTIONS

25       -cipher
26           The cipher to use.
27
28       -help
29           Print out a usage message.
30
31       -list
32           List all supported ciphers.
33
34       -ciphers
35           Alias of -list to display all supported ciphers.
36
37       -in filename
38           The input filename, standard input by default.
39
40       -out filename
41           The output filename, standard output by default.
42
43       -pass arg
44           The password source. For more information about the format of arg
45           see openssl-passphrase-options(1).
46
47       -e  Encrypt the input data: this is the default.
48
49       -d  Decrypt the input data.
50
51       -a  Base64 process the data. This means that if encryption is taking
52           place the data is base64 encoded after encryption. If decryption is
53           set then the input data is base64 decoded before being decrypted.
54
55       -base64
56           Same as -a
57
58       -A  If the -a option is set then base64 process the data on one line.
59
60       -k password
61           The password to derive the key from. This is for compatibility with
62           previous versions of OpenSSL. Superseded by the -pass argument.
63
64       -kfile filename
65           Read the password to derive the key from the first line of
66           filename.  This is for compatibility with previous versions of
67           OpenSSL. Superseded by the -pass argument.
68
69       -md digest
70           Use the specified digest to create the key from the passphrase.
71           The default algorithm is sha-256.
72
73       -iter count
74           Use a given number of iterations on the password in deriving the
75           encryption key.  High values increase the time required to brute-
76           force the resulting file.  This option enables the use of PBKDF2
77           algorithm to derive the key.
78
79       -pbkdf2
80           Use PBKDF2 algorithm with a default iteration count of 10000 unless
81           otherwise specified by the -iter command line option.
82
83       -nosalt
84           Don't use a salt in the key derivation routines. This option SHOULD
85           NOT be used except for test purposes or compatibility with ancient
86           versions of OpenSSL.
87
88       -salt
89           Use salt (randomly generated or provide with -S option) when
90           encrypting, this is the default.
91
92       -S salt
93           The actual salt to use: this must be represented as a string of hex
94           digits.  If this option is used while encrypting, the same exact
95           value will be needed again during decryption.
96
97       -K key
98           The actual key to use: this must be represented as a string
99           comprised only of hex digits. If only the key is specified, the IV
100           must additionally specified using the -iv option. When both a key
101           and a password are specified, the key given with the -K option will
102           be used and the IV generated from the password will be taken. It
103           does not make much sense to specify both key and password.
104
105       -iv IV
106           The actual IV to use: this must be represented as a string
107           comprised only of hex digits. When only the key is specified using
108           the -K option, the IV must explicitly be defined. When a password
109           is being specified using one of the other options, the IV is
110           generated from this password.
111
112       -p  Print out the key and IV used.
113
114       -P  Print out the key and IV used then immediately exit: don't do any
115           encryption or decryption.
116
117       -bufsize number
118           Set the buffer size for I/O.
119
120       -nopad
121           Disable standard block padding.
122
123       -v  Verbose print; display some statistics about I/O and buffer sizes.
124
125       -debug
126           Debug the BIOs used for I/O.
127
128       -z  Compress or decompress encrypted data using zlib after encryption
129           or before decryption. This option exists only if OpenSSL was
130           compiled with the zlib or zlib-dynamic option.
131
132       -none
133           Use NULL cipher (no encryption or decryption of input).
134
135       -rand files, -writerand file
136           See "Random State Options" in openssl(1) for details.
137
138       -provider name
139       -provider-path path
140       -propquery propq
141           See "Provider Options" in openssl(1), provider(7), and property(7).
142
143       -engine id
144           See "Engine Options" in openssl(1).  This option is deprecated.
145

NOTES

147       The program can be called either as "openssl cipher" or "openssl enc
148       -cipher". The first form doesn't work with engine-provided ciphers,
149       because this form is processed before the configuration file is read
150       and any ENGINEs loaded.  Use the openssl-list(1) command to get a list
151       of supported ciphers.
152
153       Engines which provide entirely new encryption algorithms (such as the
154       ccgost engine which provides gost89 algorithm) should be configured in
155       the configuration file. Engines specified on the command line using
156       -engine option can only be used for hardware-assisted implementations
157       of ciphers which are supported by the OpenSSL core or another engine
158       specified in the configuration file.
159
160       When the enc command lists supported ciphers, ciphers provided by
161       engines, specified in the configuration files are listed too.
162
163       A password will be prompted for to derive the key and IV if necessary.
164
165       The -salt option should ALWAYS be used if the key is being derived from
166       a password unless you want compatibility with previous versions of
167       OpenSSL.
168
169       Without the -salt option it is possible to perform efficient dictionary
170       attacks on the password and to attack stream cipher encrypted data. The
171       reason for this is that without the salt the same password always
172       generates the same encryption key.
173
174       When the salt is generated at random (that means when encrypting using
175       a passphrase without explicit salt given using -S option), the first
176       bytes of the encrypted data are reserved to store the salt for later
177       decrypting.
178
179       Some of the ciphers do not have large keys and others have security
180       implications if not used correctly. A beginner is advised to just use a
181       strong block cipher, such as AES, in CBC mode.
182
183       All the block ciphers normally use PKCS#5 padding, also known as
184       standard block padding. This allows a rudimentary integrity or password
185       check to be performed. However, since the chance of random data passing
186       the test is better than 1 in 256 it isn't a very good test.
187
188       If padding is disabled then the input data must be a multiple of the
189       cipher block length.
190
191       All RC2 ciphers have the same key and effective key length.
192
193       Blowfish and RC5 algorithms use a 128 bit key.
194
195       Please note that OpenSSL 3.0 changed the effect of the -S option.  Any
196       explicit salt value specified via this option is no longer prepended to
197       the ciphertext when encrypting, and must again be explicitly provided
198       when decrypting.  Conversely, when the -S option is used during
199       decryption, the ciphertext is expected to not have a prepended salt
200       value.
201
202       When using OpenSSL 3.0 or later to decrypt data that was encrypted with
203       an explicit salt under OpenSSL 1.1.1 do not use the -S option, the salt
204       will then be read from the ciphertext.  To generate ciphertext that can
205       be decrypted with OpenSSL 1.1.1 do not use the -S option, the salt will
206       be then be generated randomly and prepended to the output.
207

SUPPORTED CIPHERS

209       Note that some of these ciphers can be disabled at compile time and
210       some are available only if an appropriate engine is configured in the
211       configuration file. The output when invoking this command with the
212       -list option (that is "openssl enc -list") is a list of ciphers,
213       supported by your version of OpenSSL, including ones provided by
214       configured engines.
215
216       This command does not support authenticated encryption modes like CCM
217       and GCM, and will not support such modes in the future.  This is due to
218       having to begin streaming output (e.g., to standard output when -out is
219       not used) before the authentication tag could be validated.  When this
220       command is used in a pipeline, the receiving end will not be able to
221       roll back upon authentication failure.  The AEAD modes currently in
222       common use also suffer from catastrophic failure of confidentiality
223       and/or integrity upon reuse of key/iv/nonce, and since openssl enc
224       places the entire burden of key/iv/nonce management upon the user, the
225       risk of exposing AEAD modes is too great to allow.  These key/iv/nonce
226       management issues also affect other modes currently exposed in this
227       command, but the failure modes are less extreme in these cases, and the
228       functionality cannot be removed with a stable release branch.  For bulk
229       encryption of data, whether using authenticated encryption modes or
230       other modes, openssl-cms(1) is recommended, as it provides a standard
231       data format and performs the needed key/iv/nonce management.
232
233        base64             Base 64
234
235        bf-cbc             Blowfish in CBC mode
236        bf                 Alias for bf-cbc
237        blowfish           Alias for bf-cbc
238        bf-cfb             Blowfish in CFB mode
239        bf-ecb             Blowfish in ECB mode
240        bf-ofb             Blowfish in OFB mode
241
242        cast-cbc           CAST in CBC mode
243        cast               Alias for cast-cbc
244        cast5-cbc          CAST5 in CBC mode
245        cast5-cfb          CAST5 in CFB mode
246        cast5-ecb          CAST5 in ECB mode
247        cast5-ofb          CAST5 in OFB mode
248
249        chacha20           ChaCha20 algorithm
250
251        des-cbc            DES in CBC mode
252        des                Alias for des-cbc
253        des-cfb            DES in CFB mode
254        des-ofb            DES in OFB mode
255        des-ecb            DES in ECB mode
256
257        des-ede-cbc        Two key triple DES EDE in CBC mode
258        des-ede            Two key triple DES EDE in ECB mode
259        des-ede-cfb        Two key triple DES EDE in CFB mode
260        des-ede-ofb        Two key triple DES EDE in OFB mode
261
262        des-ede3-cbc       Three key triple DES EDE in CBC mode
263        des-ede3           Three key triple DES EDE in ECB mode
264        des3               Alias for des-ede3-cbc
265        des-ede3-cfb       Three key triple DES EDE CFB mode
266        des-ede3-ofb       Three key triple DES EDE in OFB mode
267
268        desx               DESX algorithm.
269
270        gost89             GOST 28147-89 in CFB mode (provided by ccgost engine)
271        gost89-cnt         GOST 28147-89 in CNT mode (provided by ccgost engine)
272
273        idea-cbc           IDEA algorithm in CBC mode
274        idea               same as idea-cbc
275        idea-cfb           IDEA in CFB mode
276        idea-ecb           IDEA in ECB mode
277        idea-ofb           IDEA in OFB mode
278
279        rc2-cbc            128 bit RC2 in CBC mode
280        rc2                Alias for rc2-cbc
281        rc2-cfb            128 bit RC2 in CFB mode
282        rc2-ecb            128 bit RC2 in ECB mode
283        rc2-ofb            128 bit RC2 in OFB mode
284        rc2-64-cbc         64 bit RC2 in CBC mode
285        rc2-40-cbc         40 bit RC2 in CBC mode
286
287        rc4                128 bit RC4
288        rc4-64             64 bit RC4
289        rc4-40             40 bit RC4
290
291        rc5-cbc            RC5 cipher in CBC mode
292        rc5                Alias for rc5-cbc
293        rc5-cfb            RC5 cipher in CFB mode
294        rc5-ecb            RC5 cipher in ECB mode
295        rc5-ofb            RC5 cipher in OFB mode
296
297        seed-cbc           SEED cipher in CBC mode
298        seed               Alias for seed-cbc
299        seed-cfb           SEED cipher in CFB mode
300        seed-ecb           SEED cipher in ECB mode
301        seed-ofb           SEED cipher in OFB mode
302
303        sm4-cbc            SM4 cipher in CBC mode
304        sm4                Alias for sm4-cbc
305        sm4-cfb            SM4 cipher in CFB mode
306        sm4-ctr            SM4 cipher in CTR mode
307        sm4-ecb            SM4 cipher in ECB mode
308        sm4-ofb            SM4 cipher in OFB mode
309
310        aes-[128|192|256]-cbc  128/192/256 bit AES in CBC mode
311        aes[128|192|256]       Alias for aes-[128|192|256]-cbc
312        aes-[128|192|256]-cfb  128/192/256 bit AES in 128 bit CFB mode
313        aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
314        aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
315        aes-[128|192|256]-ctr  128/192/256 bit AES in CTR mode
316        aes-[128|192|256]-ecb  128/192/256 bit AES in ECB mode
317        aes-[128|192|256]-ofb  128/192/256 bit AES in OFB mode
318
319        aria-[128|192|256]-cbc  128/192/256 bit ARIA in CBC mode
320        aria[128|192|256]       Alias for aria-[128|192|256]-cbc
321        aria-[128|192|256]-cfb  128/192/256 bit ARIA in 128 bit CFB mode
322        aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
323        aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
324        aria-[128|192|256]-ctr  128/192/256 bit ARIA in CTR mode
325        aria-[128|192|256]-ecb  128/192/256 bit ARIA in ECB mode
326        aria-[128|192|256]-ofb  128/192/256 bit ARIA in OFB mode
327
328        camellia-[128|192|256]-cbc  128/192/256 bit Camellia in CBC mode
329        camellia[128|192|256]       Alias for camellia-[128|192|256]-cbc
330        camellia-[128|192|256]-cfb  128/192/256 bit Camellia in 128 bit CFB mode
331        camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
332        camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
333        camellia-[128|192|256]-ctr  128/192/256 bit Camellia in CTR mode
334        camellia-[128|192|256]-ecb  128/192/256 bit Camellia in ECB mode
335        camellia-[128|192|256]-ofb  128/192/256 bit Camellia in OFB mode
336

EXAMPLES

338       Just base64 encode a binary file:
339
340        openssl base64 -in file.bin -out file.b64
341
342       Decode the same file
343
344        openssl base64 -d -in file.b64 -out file.bin
345
346       Encrypt a file using AES-128 using a prompted password and PBKDF2 key
347       derivation:
348
349        openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
350
351       Decrypt a file using a supplied password:
352
353        openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
354           -pass pass:<password>
355
356       Encrypt a file then base64 encode it (so it can be sent via mail for
357       example) using AES-256 in CTR mode and PBKDF2 key derivation:
358
359        openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
360
361       Base64 decode a file then decrypt it using a password supplied in a
362       file:
363
364        openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
365           -pass file:<passfile>
366

BUGS

368       The -A option when used with large files doesn't work properly.
369
370       The openssl enc command only supports a fixed number of algorithms with
371       certain parameters. So if, for example, you want to use RC2 with a 76
372       bit key or RC4 with an 84 bit key you can't use this program.
373

HISTORY

375       The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
376
377       The -list option was added in OpenSSL 1.1.1e.
378
379       The -ciphers and -engine options were deprecated in OpenSSL 3.0.
380
382       Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.
383
384       Licensed under the Apache License 2.0 (the "License").  You may not use
385       this file except in compliance with the License.  You can obtain a copy
386       in the file LICENSE in the source distribution or at
387       <https://www.openssl.org/source/license.html>.
388
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3913.1.1                             2023-08-31                OPENSSL-ENC(1ossl)
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