doc/apps/enc.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 enc - symmetric cipher routines
   6
   7 =head1 SYNOPSIS
   8
   9 B<openssl enc -ciphername>
  10 [B<-in filename>]
  11 [B<-out filename>]
  12 [B<-pass arg>]
  13 [B<-e>]
  14 [B<-d>]
  15 [B<-a/-base64>]
  16 [B<-A>]
  17 [B<-k password>]
  18 [B<-kfile filename>]
  19 [B<-K key>]
  20 [B<-iv IV>]
  21 [B<-S salt>]
  22 [B<-salt>]
  23 [B<-nosalt>]
  24 [B<-z>]
  25 [B<-md>]
  26 [B<-p>]
  27 [B<-P>]
  28 [B<-bufsize number>]
  29 [B<-nopad>]
  30 [B<-debug>]
  31 [B<-none>]
  32 [B<-engine id>]
  33
  34 =head1 DESCRIPTION
  35
  36 The symmetric cipher commands allow data to be encrypted or decrypted
  37 using various block and stream ciphers using keys based on passwords
  38 or explicitly provided. Base64 encoding or decoding can also be performed
  39 either by itself or in addition to the encryption or decryption.
  40
  41 =head1 OPTIONS
  42
  43 =over 4
  44
  45 =item B<-in filename>
  46
  47 the input filename, standard input by default.
  48
  49 =item B<-out filename>
  50
  51 the output filename, standard output by default.
  52
  53 =item B<-pass arg>
  54
  55 the password source. For more information about the format of B<arg>
  56 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
  57
  58 =item B<-salt>
  59
  60 use a salt in the key derivation routines. This is the default.
  61
  62 =item B<-nosalt>
  63
  64 don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
  65 used except for test purposes or compatibility with ancient versions of OpenSSL.
  66
  67 =item B<-e>
  68
  69 encrypt the input data: this is the default.
  70
  71 =item B<-d>
  72
  73 decrypt the input data.
  74
  75 =item B<-a>
  76
  77 base64 process the data. This means that if encryption is taking place
  78 the data is base64 encoded after encryption. If decryption is set then
  79 the input data is base64 decoded before being decrypted.
  80
  81 =item B<-base64>
  82
  83 same as B<-a>
  84
  85 =item B<-A>
  86
  87 if the B<-a> option is set then base64 process the data on one line.
  88
  89 =item B<-k password>
  90
  91 the password to derive the key from. This is for compatibility with previous
  92 versions of OpenSSL. Superseded by the B<-pass> argument.
  93
  94 =item B<-kfile filename>
  95
  96 read the password to derive the key from the first line of B<filename>.
  97 This is for compatibility with previous versions of OpenSSL. Superseded by
  98 the B<-pass> argument.
  99
 100 =item B<-nosalt>
 101
 102 do not use a salt
 103
 104 =item B<-salt>
 105
 106 use salt (randomly generated or provide with B<-S> option) when
 107 encrypting (this is the default).
 108
 109 =item B<-S salt>
 110
 111 the actual salt to use: this must be represented as a string of hex digits.
 112
 113 =item B<-K key>
 114
 115 the actual key to use: this must be represented as a string comprised only
 116 of hex digits. If only the key is specified, the IV must additionally specified
 117 using the B<-iv> option. When both a key and a password are specified, the
 118 key given with the B<-K> option will be used and the IV generated from the
 119 password will be taken. It probably does not make much sense to specify
 120 both key and password.
 121
 122 =item B<-iv IV>
 123
 124 the actual IV to use: this must be represented as a string comprised only
 125 of hex digits. When only the key is specified using the B<-K> option, the
 126 IV must explicitly be defined. When a password is being specified using
 127 one of the other options, the IV is generated from this password.
 128
 129 =item B<-p>
 130
 131 print out the key and IV used.
 132
 133 =item B<-P>
 134
 135 print out the key and IV used then immediately exit: don't do any encryption
 136 or decryption.
 137
 138 =item B<-bufsize number>
 139
 140 set the buffer size for I/O
 141
 142 =item B<-nopad>
 143
 144 disable standard block padding
 145
 146 =item B<-debug>
 147
 148 debug the BIOs used for I/O.
 149
 150 =item B<-z>
 151
 152 Compress or decompress clear text using zlib before encryption or after
 153 decryption. This option exists only if OpenSSL with compiled with zlib
 154 or zlib-dynamic option.
 155
 156 =item B<-none>
 157
 158 Use NULL cipher (no encryption or decryption of input).
 159
 160 =back
 161
 162 =head1 NOTES
 163
 164 The program can be called either as B<openssl ciphername> or
 165 B<openssl enc -ciphername>. But the first form doesn't work with
 166 engine-provided ciphers, because this form is processed before the
 167 configuration file is read and any ENGINEs loaded.
 168
 169 Engines which provide entirely new encryption algorithms (such as ccgost
 170 engine which provides gost89 algorithm) should be configured in the
 171 configuration file. Engines, specified in the command line using -engine
 172 options can only be used for hardware-assisted implementations of
 173 ciphers, which are supported by OpenSSL core or other engine, specified
 174 in the configuration file.
 175
 176 When enc command lists supported ciphers, ciphers provided by engines,
 177 specified in the configuration files are listed too.
 178
 179 A password will be prompted for to derive the key and IV if necessary.
 180
 181 The B<-salt> option should B<ALWAYS> be used if the key is being derived
 182 from a password unless you want compatibility with previous versions of
 183 OpenSSL.
 184
 185 Without the B<-salt> option it is possible to perform efficient dictionary
 186 attacks on the password and to attack stream cipher encrypted data. The reason
 187 for this is that without the salt the same password always generates the same
 188 encryption key. When the salt is being used the first eight bytes of the
 189 encrypted data are reserved for the salt: it is generated at random when
 190 encrypting a file and read from the encrypted file when it is decrypted.
 191
 192 Some of the ciphers do not have large keys and others have security
 193 implications if not used correctly. A beginner is advised to just use
 194 a strong block cipher in CBC mode such as bf or des3.
 195
 196 All the block ciphers normally use PKCS#5 padding also known as standard block
 197 padding: this allows a rudimentary integrity or password check to be
 198 performed. However since the chance of random data passing the test is
 199 better than 1 in 256 it isn't a very good test.
 200
 201 If padding is disabled then the input data must be a multiple of the cipher
 202 block length.
 203
 204 All RC2 ciphers have the same key and effective key length.
 205
 206 Blowfish and RC5 algorithms use a 128 bit key.
 207
 208 =head1 SUPPORTED CIPHERS
 209
 210 Note that some of these ciphers can be disabled at compile time
 211 and some are available only if an appropriate engine is configured
 212 in the configuration file. The output of the B<enc> command run with
 213 unsupported options (for example B<openssl enc -help>) includes a
 214 list of ciphers, supported by your version of OpenSSL, including
 215 ones provided by configured engines.
 216
 217 The B<enc> program does not support authenticated encryption modes
 218 like CCM and GCM. The utility does not store or retrieve the
 219 authentication tag.
 220
 221
 222  base64             Base 64
 223
 224  bf-cbc             Blowfish in CBC mode
 225  bf                 Alias for bf-cbc
 226  bf-cfb             Blowfish in CFB mode
 227  bf-ecb             Blowfish in ECB mode
 228  bf-ofb             Blowfish in OFB mode
 229
 230  cast-cbc           CAST in CBC mode
 231  cast               Alias for cast-cbc
 232  cast5-cbc          CAST5 in CBC mode
 233  cast5-cfb          CAST5 in CFB mode
 234  cast5-ecb          CAST5 in ECB mode
 235  cast5-ofb          CAST5 in OFB mode
 236
 237  des-cbc            DES in CBC mode
 238  des                Alias for des-cbc
 239  des-cfb            DES in CBC mode
 240  des-ofb            DES in OFB mode
 241  des-ecb            DES in ECB mode
 242
 243  des-ede-cbc        Two key triple DES EDE in CBC mode
 244  des-ede            Two key triple DES EDE in ECB mode
 245  des-ede-cfb        Two key triple DES EDE in CFB mode
 246  des-ede-ofb        Two key triple DES EDE in OFB mode
 247
 248  des-ede3-cbc       Three key triple DES EDE in CBC mode
 249  des-ede3           Three key triple DES EDE in ECB mode
 250  des3               Alias for des-ede3-cbc
 251  des-ede3-cfb       Three key triple DES EDE CFB mode
 252  des-ede3-ofb       Three key triple DES EDE in OFB mode
 253
 254  desx               DESX algorithm.
 255
 256  gost89             GOST 28147-89 in CFB mode (provided by ccgost engine)
 257  gost89-cnt        `GOST 28147-89 in CNT mode (provided by ccgost engine)
 258
 259  idea-cbc           IDEA algorithm in CBC mode
 260  idea               same as idea-cbc
 261  idea-cfb           IDEA in CFB mode
 262  idea-ecb           IDEA in ECB mode
 263  idea-ofb           IDEA in OFB mode
 264
 265  rc2-cbc            128 bit RC2 in CBC mode
 266  rc2                Alias for rc2-cbc
 267  rc2-cfb            128 bit RC2 in CFB mode
 268  rc2-ecb            128 bit RC2 in ECB mode
 269  rc2-ofb            128 bit RC2 in OFB mode
 270  rc2-64-cbc         64 bit RC2 in CBC mode
 271  rc2-40-cbc         40 bit RC2 in CBC mode
 272
 273  rc4                128 bit RC4
 274  rc4-64             64 bit RC4
 275  rc4-40             40 bit RC4
 276
 277  rc5-cbc            RC5 cipher in CBC mode
 278  rc5                Alias for rc5-cbc
 279  rc5-cfb            RC5 cipher in CFB mode
 280  rc5-ecb            RC5 cipher in ECB mode
 281  rc5-ofb            RC5 cipher in OFB mode
 282
 283  aes-[128|192|256]-cbc  128/192/256 bit AES in CBC mode
 284  aes[128|192|256]       Alias for aes-[128|192|256]-cbc
 285  aes-[128|192|256]-cfb  128/192/256 bit AES in 128 bit CFB mode
 286  aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
 287  aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
 288  aes-[128|192|256]-ecb  128/192/256 bit AES in ECB mode
 289  aes-[128|192|256]-ofb  128/192/256 bit AES in OFB mode
 290
 291 =head1 EXAMPLES
 292
 293 Just base64 encode a binary file:
 294
 295  openssl base64 -in file.bin -out file.b64
 296
 297 Decode the same file
 298
 299  openssl base64 -d -in file.b64 -out file.bin
 300
 301 Encrypt a file using triple DES in CBC mode using a prompted password:
 302
 303  openssl des3 -salt -in file.txt -out file.des3
 304
 305 Decrypt a file using a supplied password:
 306
 307  openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
 308
 309 Encrypt a file then base64 encode it (so it can be sent via mail for example)
 310 using Blowfish in CBC mode:
 311
 312  openssl bf -a -salt -in file.txt -out file.bf
 313
 314 Base64 decode a file then decrypt it:
 315
 316  openssl bf -d -salt -a -in file.bf -out file.txt
 317
 318 Decrypt some data using a supplied 40 bit RC4 key:
 319
 320  openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
 321
 322 =head1 BUGS
 323
 324 The B<-A> option when used with large files doesn't work properly.
 325
 326 There should be an option to allow an iteration count to be included.
 327
 328 The B<enc> program only supports a fixed number of algorithms with
 329 certain parameters. So if, for example, you want to use RC2 with a
 330 76 bit key or RC4 with an 84 bit key you can't use this program.
 331
 332 =cut