doc/man1/openssl-enc.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 openssl-enc - symmetric cipher routines
   6
   7 =head1 SYNOPSIS
   8
   9 B<openssl>
  10 [B<->I<cipher>]
  11 [B<-help>]
  12 [B<-ciphers>]
  13 [B<-in> I<filename>]
  14 [B<-out> I<filename>]
  15 [B<-pass> I<arg>]
  16 [B<-e>]
  17 [B<-d>]
  18 [B<-a>]
  19 [B<-base64>]
  20 [B<-A>]
  21 [B<-k> I<password>]
  22 [B<-kfile> I<filename>]
  23 [B<-K> I<key>]
  24 [B<-iv> I<IV>]
  25 [B<-S> I<salt>]
  26 [B<-salt>]
  27 [B<-nosalt>]
  28 [B<-z>]
  29 [B<-md> I<digest>]
  30 [B<-iter> I<count>]
  31 [B<-pbkdf2>]
  32 [B<-p>]
  33 [B<-P>]
  34 [B<-bufsize> I<number>]
  35 [B<-nopad>]
  36 [B<-debug>]
  37 [B<-none>]
  38 [B<-rand> I<file...>]
  39 [B<-writerand> I<file>]
  40 [B<-engine> I<id>]
  41
  42 =for comment ifdef z engine
  43
  44 B<openssl> I<cipher> [B<...>]
  45
  46 =head1 DESCRIPTION
  47
  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.
  52
  53 =head1 OPTIONS
  54
  55 =over 4
  56
  57 =item B<-help>
  58
  59 Print out a usage message.
  60
  61 =item B<-ciphers>
  62
  63 List all supported ciphers.
  64
  65 =item B<-in> I<filename>
  66
  67 The input filename, standard input by default.
  68
  69 =item B<-out> I<filename>
  70
  71 The output filename, standard output by default.
  72
  73 =item B<-pass> I<arg>
  74
  75 The password source. For more information about the format of B<arg>
  76 see L<openssl(1)/Pass phrase options>.
  77
  78 =item B<-e>
  79
  80 Encrypt the input data: this is the default.
  81
  82 =item B<-d>
  83
  84 Decrypt the input data.
  85
  86 =item B<-a>
  87
  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.
  91
  92 =item B<-base64>
  93
  94 Same as B<-a>
  95
  96 =item B<-A>
  97
  98 If the B<-a> option is set then base64 process the data on one line.
  99
 100 =item B<-k> I<password>
 101
 102 The password to derive the key from. This is for compatibility with previous
 103 versions of OpenSSL. Superseded by the B<-pass> argument.
 104
 105 =item B<-kfile> I<filename>
 106
 107 Read the password to derive the key from the first line of B<filename>.
 108 This is for compatibility with previous versions of OpenSSL. Superseded by
 109 the B<-pass> argument.
 110
 111 =item B<-md> I<digest>
 112
 113 Use the specified digest to create the key from the passphrase.
 114 The default algorithm is sha-256.
 115
 116 =item B<-iter> I<count>
 117
 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.
 121
 122 =item B<-pbkdf2>
 123
 124 Use PBKDF2 algorithm with default iteration count unless otherwise specified.
 125
 126 =item B<-nosalt>
 127
 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
 130 OpenSSL.
 131
 132 =item B<-salt>
 133
 134 Use salt (randomly generated or provide with B<-S> option) when
 135 encrypting, this is the default.
 136
 137 =item B<-S> I<salt>
 138
 139 The actual salt to use: this must be represented as a string of hex digits.
 140
 141 =item B<-K> I<key>
 142
 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
 148 and password.
 149
 150 =item B<-iv> I<IV>
 151
 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.
 156
 157 =item B<-p>
 158
 159 Print out the key and IV used.
 160
 161 =item B<-P>
 162
 163 Print out the key and IV used then immediately exit: don't do any encryption
 164 or decryption.
 165
 166 =item B<-bufsize> I<number>
 167
 168 Set the buffer size for I/O.
 169
 170 =item B<-nopad>
 171
 172 Disable standard block padding.
 173
 174 =item B<-debug>
 175
 176 Debug the BIOs used for I/O.
 177
 178 =item B<-z>
 179
 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.
 183
 184 =item B<-none>
 185
 186 Use NULL cipher (no encryption or decryption of input).
 187
 188 =item B<-rand> I<file...>
 189
 190 A file or files containing random data used to seed the random number
 191 generator.
 192 Multiple files can be specified separated by an OS-dependent character.
 193 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
 194 all others.
 195
 196 =item B<-writerand> I<file>
 197
 198 Writes random data to the specified I<file> upon exit.
 199 This can be used with a subsequent B<-rand> flag.
 200
 201 =back
 202
 203 =head1 NOTES
 204
 205 The program can be called either as B<openssl cipher> or
 206 B<openssl enc -cipher>. The first form doesn't work with
 207 engine-provided ciphers, because this form is processed before the
 208 configuration file is read and any ENGINEs loaded.
 209 Use the B<list> command to get a list of supported ciphers.
 210
 211 Engines which provide entirely new encryption algorithms (such as the ccgost
 212 engine which provides gost89 algorithm) should be configured in the
 213 configuration file. Engines specified on the command line using -engine
 214 options can only be used for hardware-assisted implementations of
 215 ciphers which are supported by the OpenSSL core or another engine specified
 216 in the configuration file.
 217
 218 When the enc command lists supported ciphers, ciphers provided by engines,
 219 specified in the configuration files are listed too.
 220
 221 A password will be prompted for to derive the key and IV if necessary.
 222
 223 The B<-salt> option should B<ALWAYS> be used if the key is being derived
 224 from a password unless you want compatibility with previous versions of
 225 OpenSSL.
 226
 227 Without the B<-salt> option it is possible to perform efficient dictionary
 228 attacks on the password and to attack stream cipher encrypted data. The reason
 229 for this is that without the salt the same password always generates the same
 230 encryption key. When the salt is being used the first eight bytes of the
 231 encrypted data are reserved for the salt: it is generated at random when
 232 encrypting a file and read from the encrypted file when it is decrypted.
 233
 234 Some of the ciphers do not have large keys and others have security
 235 implications if not used correctly. A beginner is advised to just use
 236 a strong block cipher, such as AES, in CBC mode.
 237
 238 All the block ciphers normally use PKCS#5 padding, also known as standard
 239 block padding. This allows a rudimentary integrity or password check to
 240 be performed. However since the chance of random data passing the test
 241 is better than 1 in 256 it isn't a very good test.
 242
 243 If padding is disabled then the input data must be a multiple of the cipher
 244 block length.
 245
 246 All RC2 ciphers have the same key and effective key length.
 247
 248 Blowfish and RC5 algorithms use a 128 bit key.
 249
 250 =head1 SUPPORTED CIPHERS
 251
 252 Note that some of these ciphers can be disabled at compile time
 253 and some are available only if an appropriate engine is configured
 254 in the configuration file. The output of the B<enc> command run with
 255 the B<-ciphers> option (that is B<openssl enc -ciphers>) produces a
 256 list of ciphers, supported by your version of OpenSSL, including
 257 ones provided by configured engines.
 258
 259 The B<enc> program does not support authenticated encryption modes
 260 like CCM and GCM, and will not support such modes in the future.
 261 The B<enc> interface by necessity must begin streaming output (e.g.,
 262 to standard output when B<-out> is not used) before the authentication
 263 tag could be validated, leading to the usage of B<enc> in pipelines
 264 that begin processing untrusted data and are not capable of rolling
 265 back upon authentication failure.  The AEAD modes currently in common
 266 use also suffer from catastrophic failure of confidentiality and/or
 267 integrity upon reuse of key/iv/nonce, and since B<enc> places the
 268 entire burden of key/iv/nonce management upon the user, the risk of
 269 exposing AEAD modes is too great to allow.  These key/iv/nonce
 270 management issues also affect other modes currently exposed in B<enc>,
 271 but the failure modes are less extreme in these cases, and the
 272 functionality cannot be removed with a stable release branch.
 273 For bulk encryption of data, whether using authenticated encryption
 274 modes or other modes, L<cms(1)> is recommended, as it provides a
 275 standard data format and performs the needed key/iv/nonce management.
 276
 277
 278  base64             Base 64
 279
 280  bf-cbc             Blowfish in CBC mode
 281  bf                 Alias for bf-cbc
 282  blowfish           Alias for bf-cbc
 283  bf-cfb             Blowfish in CFB mode
 284  bf-ecb             Blowfish in ECB mode
 285  bf-ofb             Blowfish in OFB mode
 286
 287  cast-cbc           CAST in CBC mode
 288  cast               Alias for cast-cbc
 289  cast5-cbc          CAST5 in CBC mode
 290  cast5-cfb          CAST5 in CFB mode
 291  cast5-ecb          CAST5 in ECB mode
 292  cast5-ofb          CAST5 in OFB mode
 293
 294  chacha20           ChaCha20 algorithm
 295
 296  des-cbc            DES in CBC mode
 297  des                Alias for des-cbc
 298  des-cfb            DES in CFB mode
 299  des-ofb            DES in OFB mode
 300  des-ecb            DES in ECB mode
 301
 302  des-ede-cbc        Two key triple DES EDE in CBC mode
 303  des-ede            Two key triple DES EDE in ECB mode
 304  des-ede-cfb        Two key triple DES EDE in CFB mode
 305  des-ede-ofb        Two key triple DES EDE in OFB mode
 306
 307  des-ede3-cbc       Three key triple DES EDE in CBC mode
 308  des-ede3           Three key triple DES EDE in ECB mode
 309  des3               Alias for des-ede3-cbc
 310  des-ede3-cfb       Three key triple DES EDE CFB mode
 311  des-ede3-ofb       Three key triple DES EDE in OFB mode
 312
 313  desx               DESX algorithm.
 314
 315  gost89             GOST 28147-89 in CFB mode (provided by ccgost engine)
 316  gost89-cnt        `GOST 28147-89 in CNT mode (provided by ccgost engine)
 317
 318  idea-cbc           IDEA algorithm in CBC mode
 319  idea               same as idea-cbc
 320  idea-cfb           IDEA in CFB mode
 321  idea-ecb           IDEA in ECB mode
 322  idea-ofb           IDEA in OFB mode
 323
 324  rc2-cbc            128 bit RC2 in CBC mode
 325  rc2                Alias for rc2-cbc
 326  rc2-cfb            128 bit RC2 in CFB mode
 327  rc2-ecb            128 bit RC2 in ECB mode
 328  rc2-ofb            128 bit RC2 in OFB mode
 329  rc2-64-cbc         64 bit RC2 in CBC mode
 330  rc2-40-cbc         40 bit RC2 in CBC mode
 331
 332  rc4                128 bit RC4
 333  rc4-64             64 bit RC4
 334  rc4-40             40 bit RC4
 335
 336  rc5-cbc            RC5 cipher in CBC mode
 337  rc5                Alias for rc5-cbc
 338  rc5-cfb            RC5 cipher in CFB mode
 339  rc5-ecb            RC5 cipher in ECB mode
 340  rc5-ofb            RC5 cipher in OFB mode
 341
 342  seed-cbc           SEED cipher in CBC mode
 343  seed               Alias for seed-cbc
 344  seed-cfb           SEED cipher in CFB mode
 345  seed-ecb           SEED cipher in ECB mode
 346  seed-ofb           SEED cipher in OFB mode
 347
 348  sm4-cbc            SM4 cipher in CBC mode
 349  sm4                Alias for sm4-cbc
 350  sm4-cfb            SM4 cipher in CFB mode
 351  sm4-ctr            SM4 cipher in CTR mode
 352  sm4-ecb            SM4 cipher in ECB mode
 353  sm4-ofb            SM4 cipher in OFB mode
 354
 355  aes-[128|192|256]-cbc  128/192/256 bit AES in CBC mode
 356  aes[128|192|256]       Alias for aes-[128|192|256]-cbc
 357  aes-[128|192|256]-cfb  128/192/256 bit AES in 128 bit CFB mode
 358  aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
 359  aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
 360  aes-[128|192|256]-ctr  128/192/256 bit AES in CTR mode
 361  aes-[128|192|256]-ecb  128/192/256 bit AES in ECB mode
 362  aes-[128|192|256]-ofb  128/192/256 bit AES in OFB mode
 363
 364  aria-[128|192|256]-cbc  128/192/256 bit ARIA in CBC mode
 365  aria[128|192|256]       Alias for aria-[128|192|256]-cbc
 366  aria-[128|192|256]-cfb  128/192/256 bit ARIA in 128 bit CFB mode
 367  aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
 368  aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
 369  aria-[128|192|256]-ctr  128/192/256 bit ARIA in CTR mode
 370  aria-[128|192|256]-ecb  128/192/256 bit ARIA in ECB mode
 371  aria-[128|192|256]-ofb  128/192/256 bit ARIA in OFB mode
 372
 373  camellia-[128|192|256]-cbc  128/192/256 bit Camellia in CBC mode
 374  camellia[128|192|256]       Alias for camellia-[128|192|256]-cbc
 375  camellia-[128|192|256]-cfb  128/192/256 bit Camellia in 128 bit CFB mode
 376  camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
 377  camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
 378  camellia-[128|192|256]-ctr  128/192/256 bit Camellia in CTR mode
 379  camellia-[128|192|256]-ecb  128/192/256 bit Camellia in ECB mode
 380  camellia-[128|192|256]-ofb  128/192/256 bit Camellia in OFB mode
 381
 382 =head1 EXAMPLES
 383
 384 Just base64 encode a binary file:
 385
 386  openssl base64 -in file.bin -out file.b64
 387
 388 Decode the same file
 389
 390  openssl base64 -d -in file.b64 -out file.bin
 391
 392 Encrypt a file using AES-128 using a prompted password
 393 and PBKDF2 key derivation:
 394
 395  openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
 396
 397 Decrypt a file using a supplied password:
 398
 399  openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
 400     -pass pass:<password>
 401
 402 Encrypt a file then base64 encode it (so it can be sent via mail for example)
 403 using AES-256 in CTR mode and PBKDF2 key derivation:
 404
 405  openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
 406
 407 Base64 decode a file then decrypt it using a password supplied in a file:
 408
 409  openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
 410     -pass file:<passfile>
 411
 412 =head1 BUGS
 413
 414 The B<-A> option when used with large files doesn't work properly.
 415
 416 The B<enc> program only supports a fixed number of algorithms with
 417 certain parameters. So if, for example, you want to use RC2 with a
 418 76 bit key or RC4 with an 84 bit key you can't use this program.
 419
 420 =head1 HISTORY
 421
 422 The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
 423
 424 =head1 COPYRIGHT
 425
 426 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
 427
 428 Licensed under the Apache License 2.0 (the "License").  You may not use
 429 this file except in compliance with the License.  You can obtain a copy
 430 in the file LICENSE in the source distribution or at
 431 L<https://www.openssl.org/source/license.html>.
 432
 433 =cut