1=pod 2{- OpenSSL::safe::output_do_not_edit_headers(); -} 3 4=head1 NAME 5 6openssl-enc - symmetric cipher routines 7 8=head1 SYNOPSIS 9 10B<openssl> B<enc>|I<cipher> 11[B<-I<cipher>>] 12[B<-help>] 13[B<-list>] 14[B<-ciphers>] 15[B<-in> I<filename>] 16[B<-out> I<filename>] 17[B<-pass> I<arg>] 18[B<-e>] 19[B<-d>] 20[B<-a>] 21[B<-base64>] 22[B<-A>] 23[B<-k> I<password>] 24[B<-kfile> I<filename>] 25[B<-K> I<key>] 26[B<-iv> I<IV>] 27[B<-S> I<salt>] 28[B<-salt>] 29[B<-nosalt>] 30[B<-z>] 31[B<-md> I<digest>] 32[B<-iter> I<count>] 33[B<-pbkdf2>] 34[B<-p>] 35[B<-P>] 36[B<-bufsize> I<number>] 37[B<-nopad>] 38[B<-v>] 39[B<-debug>] 40[B<-none>] 41{- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_r_synopsis -} 42{- $OpenSSL::safe::opt_provider_synopsis -} 43 44B<openssl> I<cipher> [B<...>] 45 46=head1 DESCRIPTION 47 48The symmetric cipher commands allow data to be encrypted or decrypted 49using various block and stream ciphers using keys based on passwords 50or explicitly provided. Base64 encoding or decoding can also be performed 51either by itself or in addition to the encryption or decryption. 52 53=head1 OPTIONS 54 55=over 4 56 57=item B<-I<cipher>> 58 59The cipher to use. 60 61=item B<-help> 62 63Print out a usage message. 64 65=item B<-list> 66 67List all supported ciphers. 68 69=item B<-ciphers> 70 71Alias of -list to display all supported ciphers. 72 73=item B<-in> I<filename> 74 75The input filename, standard input by default. 76 77=item B<-out> I<filename> 78 79The output filename, standard output by default. 80 81=item B<-pass> I<arg> 82 83The password source. For more information about the format of I<arg> 84see L<openssl-passphrase-options(1)>. 85 86=item B<-e> 87 88Encrypt the input data: this is the default. 89 90=item B<-d> 91 92Decrypt the input data. 93 94=item B<-a> 95 96Base64 process the data. This means that if encryption is taking place 97the data is base64 encoded after encryption. If decryption is set then 98the input data is base64 decoded before being decrypted. 99 100When the B<-A> option not given, 101on encoding a newline is inserted after each 64 characters, and 102on decoding a newline is expected among the first 1024 bytes of input. 103 104=item B<-base64> 105 106Same as B<-a> 107 108=item B<-A> 109 110If the B<-a> option is set then base64 encoding produces output without any 111newline character, and base64 decoding does not require any newlines. 112Therefore it can be helpful to use the B<-A> option when decoding unknown input. 113 114=item B<-k> I<password> 115 116The password to derive the key from. This is for compatibility with previous 117versions of OpenSSL. Superseded by the B<-pass> argument. 118 119=item B<-kfile> I<filename> 120 121Read the password to derive the key from the first line of I<filename>. 122This is for compatibility with previous versions of OpenSSL. Superseded by 123the B<-pass> argument. 124 125=item B<-md> I<digest> 126 127Use the specified digest to create the key from the passphrase. 128The default algorithm is sha-256. 129 130=item B<-iter> I<count> 131 132Use a given number of iterations on the password in deriving the encryption key. 133High values increase the time required to brute-force the resulting file. 134This option enables the use of PBKDF2 algorithm to derive the key. 135 136=item B<-pbkdf2> 137 138Use PBKDF2 algorithm with a default iteration count of 10000 139unless otherwise specified by the B<-iter> command line option. 140 141=item B<-nosalt> 142 143Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be 144used except for test purposes or compatibility with ancient versions of 145OpenSSL. 146 147=item B<-salt> 148 149Use salt (randomly generated or provide with B<-S> option) when 150encrypting, this is the default. 151 152=item B<-S> I<salt> 153 154The actual salt to use: this must be represented as a string of hex digits. 155If this option is used while encrypting, the same exact value will be needed 156again during decryption. 157 158=item B<-K> I<key> 159 160The actual key to use: this must be represented as a string comprised only 161of hex digits. If only the key is specified, the IV must additionally specified 162using the B<-iv> option. When both a key and a password are specified, the 163key given with the B<-K> option will be used and the IV generated from the 164password will be taken. It does not make much sense to specify both key 165and password. 166 167=item B<-iv> I<IV> 168 169The actual IV to use: this must be represented as a string comprised only 170of hex digits. When only the key is specified using the B<-K> option, the 171IV must explicitly be defined. When a password is being specified using 172one of the other options, the IV is generated from this password. 173 174=item B<-p> 175 176Print out the key and IV used. 177 178=item B<-P> 179 180Print out the key and IV used then immediately exit: don't do any encryption 181or decryption. 182 183=item B<-bufsize> I<number> 184 185Set the buffer size for I/O. 186 187=item B<-nopad> 188 189Disable standard block padding. 190 191=item B<-v> 192 193Verbose print; display some statistics about I/O and buffer sizes. 194 195=item B<-debug> 196 197Debug the BIOs used for I/O. 198 199=item B<-z> 200 201Compress or decompress encrypted data using zlib after encryption or before 202decryption. This option exists only if OpenSSL was compiled with the zlib 203or zlib-dynamic option. 204 205=item B<-none> 206 207Use NULL cipher (no encryption or decryption of input). 208 209{- $OpenSSL::safe::opt_r_item -} 210 211{- $OpenSSL::safe::opt_provider_item -} 212 213{- $OpenSSL::safe::opt_engine_item -} 214 215=back 216 217=head1 NOTES 218 219The program can be called either as C<openssl I<cipher>> or 220C<openssl enc -I<cipher>>. The first form doesn't work with 221engine-provided ciphers, because this form is processed before the 222configuration file is read and any ENGINEs loaded. 223Use the L<openssl-list(1)> command to get a list of supported ciphers. 224 225Engines which provide entirely new encryption algorithms (such as the ccgost 226engine which provides gost89 algorithm) should be configured in the 227configuration file. Engines specified on the command line using B<-engine> 228option can only be used for hardware-assisted implementations of 229ciphers which are supported by the OpenSSL core or another engine specified 230in the configuration file. 231 232When the enc command lists supported ciphers, ciphers provided by engines, 233specified in the configuration files are listed too. 234 235A password will be prompted for to derive the key and IV if necessary. 236 237The B<-salt> option should B<ALWAYS> be used if the key is being derived 238from a password unless you want compatibility with previous versions of 239OpenSSL. 240 241Without the B<-salt> option it is possible to perform efficient dictionary 242attacks on the password and to attack stream cipher encrypted data. The reason 243for this is that without the salt the same password always generates the same 244encryption key. 245 246When the salt is generated at random (that means when encrypting using a 247passphrase without explicit salt given using B<-S> option), the first bytes 248of the encrypted data are reserved to store the salt for later decrypting. 249 250Some of the ciphers do not have large keys and others have security 251implications if not used correctly. A beginner is advised to just use 252a strong block cipher, such as AES, in CBC mode. 253 254All the block ciphers normally use PKCS#5 padding, also known as standard 255block padding. This allows a rudimentary integrity or password check to 256be performed. However, since the chance of random data passing the test 257is better than 1 in 256 it isn't a very good test. 258 259If padding is disabled then the input data must be a multiple of the cipher 260block length. 261 262All RC2 ciphers have the same key and effective key length. 263 264Blowfish and RC5 algorithms use a 128 bit key. 265 266Please note that OpenSSL 3.0 changed the effect of the B<-S> option. 267Any explicit salt value specified via this option is no longer prepended to the 268ciphertext when encrypting, and must again be explicitly provided when decrypting. 269Conversely, when the B<-S> option is used during decryption, the ciphertext 270is expected to not have a prepended salt value. 271 272When using OpenSSL 3.0 or later to decrypt data that was encrypted with an 273explicit salt under OpenSSL 1.1.1 do not use the B<-S> option, the salt will 274then be read from the ciphertext. 275To generate ciphertext that can be decrypted with OpenSSL 1.1.1 do not use 276the B<-S> option, the salt will be then be generated randomly and prepended 277to the output. 278 279=head1 SUPPORTED CIPHERS 280 281Note that some of these ciphers can be disabled at compile time 282and some are available only if an appropriate engine is configured 283in the configuration file. The output when invoking this command 284with the B<-list> option (that is C<openssl enc -list>) is 285a list of ciphers, supported by your version of OpenSSL, including 286ones provided by configured engines. 287 288This command does not support authenticated encryption modes 289like CCM and GCM, and will not support such modes in the future. 290This is due to having to begin streaming output (e.g., to standard output 291when B<-out> is not used) before the authentication tag could be validated. 292When this command is used in a pipeline, the receiving end will not be 293able to roll back upon authentication failure. The AEAD modes currently in 294common use also suffer from catastrophic failure of confidentiality and/or 295integrity upon reuse of key/iv/nonce, and since B<openssl enc> places the 296entire burden of key/iv/nonce management upon the user, the risk of 297exposing AEAD modes is too great to allow. These key/iv/nonce 298management issues also affect other modes currently exposed in this command, 299but the failure modes are less extreme in these cases, and the 300functionality cannot be removed with a stable release branch. 301For bulk encryption of data, whether using authenticated encryption 302modes or other modes, L<openssl-cms(1)> is recommended, as it provides a 303standard data format and performs the needed key/iv/nonce management. 304 305 306 base64 Base 64 307 308 bf-cbc Blowfish in CBC mode 309 bf Alias for bf-cbc 310 blowfish Alias for bf-cbc 311 bf-cfb Blowfish in CFB mode 312 bf-ecb Blowfish in ECB mode 313 bf-ofb Blowfish in OFB mode 314 315 cast-cbc CAST in CBC mode 316 cast Alias for cast-cbc 317 cast5-cbc CAST5 in CBC mode 318 cast5-cfb CAST5 in CFB mode 319 cast5-ecb CAST5 in ECB mode 320 cast5-ofb CAST5 in OFB mode 321 322 chacha20 ChaCha20 algorithm 323 324 des-cbc DES in CBC mode 325 des Alias for des-cbc 326 des-cfb DES in CFB mode 327 des-ofb DES in OFB mode 328 des-ecb DES in ECB mode 329 330 des-ede-cbc Two key triple DES EDE in CBC mode 331 des-ede Two key triple DES EDE in ECB mode 332 des-ede-cfb Two key triple DES EDE in CFB mode 333 des-ede-ofb Two key triple DES EDE in OFB mode 334 335 des-ede3-cbc Three key triple DES EDE in CBC mode 336 des-ede3 Three key triple DES EDE in ECB mode 337 des3 Alias for des-ede3-cbc 338 des-ede3-cfb Three key triple DES EDE CFB mode 339 des-ede3-ofb Three key triple DES EDE in OFB mode 340 341 desx DESX algorithm. 342 343 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine) 344 gost89-cnt GOST 28147-89 in CNT mode (provided by ccgost engine) 345 346 idea-cbc IDEA algorithm in CBC mode 347 idea same as idea-cbc 348 idea-cfb IDEA in CFB mode 349 idea-ecb IDEA in ECB mode 350 idea-ofb IDEA in OFB mode 351 352 rc2-cbc 128 bit RC2 in CBC mode 353 rc2 Alias for rc2-cbc 354 rc2-cfb 128 bit RC2 in CFB mode 355 rc2-ecb 128 bit RC2 in ECB mode 356 rc2-ofb 128 bit RC2 in OFB mode 357 rc2-64-cbc 64 bit RC2 in CBC mode 358 rc2-40-cbc 40 bit RC2 in CBC mode 359 360 rc4 128 bit RC4 361 rc4-64 64 bit RC4 362 rc4-40 40 bit RC4 363 364 rc5-cbc RC5 cipher in CBC mode 365 rc5 Alias for rc5-cbc 366 rc5-cfb RC5 cipher in CFB mode 367 rc5-ecb RC5 cipher in ECB mode 368 rc5-ofb RC5 cipher in OFB mode 369 370 seed-cbc SEED cipher in CBC mode 371 seed Alias for seed-cbc 372 seed-cfb SEED cipher in CFB mode 373 seed-ecb SEED cipher in ECB mode 374 seed-ofb SEED cipher in OFB mode 375 376 sm4-cbc SM4 cipher in CBC mode 377 sm4 Alias for sm4-cbc 378 sm4-cfb SM4 cipher in CFB mode 379 sm4-ctr SM4 cipher in CTR mode 380 sm4-ecb SM4 cipher in ECB mode 381 sm4-ofb SM4 cipher in OFB mode 382 383 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode 384 aes[128|192|256] Alias for aes-[128|192|256]-cbc 385 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode 386 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode 387 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode 388 aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode 389 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode 390 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode 391 392 aria-[128|192|256]-cbc 128/192/256 bit ARIA in CBC mode 393 aria[128|192|256] Alias for aria-[128|192|256]-cbc 394 aria-[128|192|256]-cfb 128/192/256 bit ARIA in 128 bit CFB mode 395 aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode 396 aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode 397 aria-[128|192|256]-ctr 128/192/256 bit ARIA in CTR mode 398 aria-[128|192|256]-ecb 128/192/256 bit ARIA in ECB mode 399 aria-[128|192|256]-ofb 128/192/256 bit ARIA in OFB mode 400 401 camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode 402 camellia[128|192|256] Alias for camellia-[128|192|256]-cbc 403 camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode 404 camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode 405 camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode 406 camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode 407 camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode 408 camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode 409 410=head1 EXAMPLES 411 412Just base64 encode a binary file: 413 414 openssl base64 -in file.bin -out file.b64 415 416Decode the same file 417 418 openssl base64 -d -in file.b64 -out file.bin 419 420Encrypt a file using AES-128 using a prompted password 421and PBKDF2 key derivation: 422 423 openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128 424 425Decrypt a file using a supplied password: 426 427 openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \ 428 -pass pass:<password> 429 430Encrypt a file then base64 encode it (so it can be sent via mail for example) 431using AES-256 in CTR mode and PBKDF2 key derivation: 432 433 openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256 434 435Base64 decode a file then decrypt it using a password supplied in a file: 436 437 openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \ 438 -pass file:<passfile> 439 440=head1 BUGS 441 442The B<-A> option when used with large files doesn't work properly. 443On the other hand, when base64 decoding without the B<-A> option, 444if the first 1024 bytes of input do not include a newline character 445the first two lines of input are ignored. 446 447The B<openssl enc> command only supports a fixed number of algorithms with 448certain parameters. So if, for example, you want to use RC2 with a 44976 bit key or RC4 with an 84 bit key you can't use this program. 450 451=head1 HISTORY 452 453The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0. 454 455The B<-list> option was added in OpenSSL 1.1.1e. 456 457The B<-ciphers> and B<-engine> options were deprecated in OpenSSL 3.0. 458 459=head1 COPYRIGHT 460 461Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved. 462 463Licensed under the Apache License 2.0 (the "License"). You may not use 464this file except in compliance with the License. You can obtain a copy 465in the file LICENSE in the source distribution or at 466L<https://www.openssl.org/source/license.html>. 467 468=cut 469