6 enc - symmetric cipher routines
10 B<openssl enc -ciphername>
37 The symmetric cipher commands allow data to be encrypted or decrypted
38 using various block and stream ciphers using keys based on passwords
39 or explicitly provided. Base64 encoding or decoding can also be performed
40 either by itself or in addition to the encryption or decryption.
48 the input filename, standard input by default.
50 =item B<-out filename>
52 the output filename, standard output by default.
56 the password source. For more information about the format of B<arg>
57 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
61 use a salt in the key derivation routines. This is the default.
65 don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
66 used except for test purposes or compatibility with ancient versions of OpenSSL
71 encrypt the input data: this is the default.
75 decrypt the input data.
79 base64 process the data. This means that if encryption is taking place
80 the data is base64 encoded after encryption. If decryption is set then
81 the input data is base64 decoded before being decrypted.
89 if the B<-a> option is set then base64 process the data on one line.
93 the password to derive the key from. This is for compatibility with previous
94 versions of OpenSSL. Superseded by the B<-pass> argument.
96 =item B<-kfile filename>
98 read the password to derive the key from the first line of B<filename>.
99 This is for compatibility with previous versions of OpenSSL. Superseded by
100 the B<-pass> argument.
108 use salt (randomly generated or provide with B<-S> option) when
109 encrypting (this is the default).
113 the actual salt to use: this must be represented as a string of hex digits.
117 the actual key to use: this must be represented as a string comprised only
118 of hex digits. If only the key is specified, the IV must additionally specified
119 using the B<-iv> option. When both a key and a password are specified, the
120 key given with the B<-K> option will be used and the IV generated from the
121 password will be taken. It probably does not make much sense to specify
122 both key and password.
126 the actual IV to use: this must be represented as a string comprised only
127 of hex digits. When only the key is specified using the B<-K> option, the
128 IV must explicitly be defined. When a password is being specified using
129 one of the other options, the IV is generated from this password.
133 print out the key and IV used.
137 print out the key and IV used then immediately exit: don't do any encryption
140 =item B<-bufsize number>
142 set the buffer size for I/O
146 disable standard block padding
150 debug the BIOs used for I/O.
154 Compress or decompress clear text using zlib before encryption or after
155 decryption. This option exists only if OpenSSL with compiled with zlib
156 or zlib-dynamic option.
160 Use NULL cipher (no encryption or decryption of input).
166 The program can be called either as B<openssl ciphername> or
167 B<openssl enc -ciphername>. But the first form doesn't work with
168 engine-provided ciphers, because this form is processed before the
169 configuration file is read and any ENGINEs loaded.
171 Engines which provide entirely new encryption algorithms (such as ccgost
172 engine which provides gost89 algorithm) should be configured in the
173 configuration file. Engines, specified in the command line using -engine
174 options can only be used for hadrware-assisted implementations of
175 ciphers, which are supported by OpenSSL core or other engine, specified
176 in the configuration file.
178 When enc command lists supported ciphers, ciphers provided by engines,
179 specified in the configuration files are listed too.
181 A password will be prompted for to derive the key and IV if necessary.
183 The B<-salt> option should B<ALWAYS> be used if the key is being derived
184 from a password unless you want compatibility with previous versions of
187 Without the B<-salt> option it is possible to perform efficient dictionary
188 attacks on the password and to attack stream cipher encrypted data. The reason
189 for this is that without the salt the same password always generates the same
190 encryption key. When the salt is being used the first eight bytes of the
191 encrypted data are reserved for the salt: it is generated at random when
192 encrypting a file and read from the encrypted file when it is decrypted.
194 Some of the ciphers do not have large keys and others have security
195 implications if not used correctly. A beginner is advised to just use
196 a strong block cipher in CBC mode such as bf or des3.
198 All the block ciphers normally use PKCS#5 padding also known as standard block
199 padding: this allows a rudimentary integrity or password check to be
200 performed. However since the chance of random data passing the test is
201 better than 1 in 256 it isn't a very good test.
203 If padding is disabled then the input data must be a multiple of the cipher
206 All RC2 ciphers have the same key and effective key length.
208 Blowfish and RC5 algorithms use a 128 bit key.
210 =head1 SUPPORTED CIPHERS
212 Note that some of these ciphers can be disabled at compile time
213 and some are available only if an appropriate engine is configured
214 in the configuration file. The output of the B<enc> command run with
215 unsupported options (for example B<openssl enc -help>) includes a
216 list of ciphers, supported by your versesion of OpenSSL, including
217 ones provided by configured engines.
219 The B<enc> program does not support authenticated encryption modes
220 like CCM and GCM. The utility does not store or retrieve the
226 bf-cbc Blowfish in CBC mode
228 bf-cfb Blowfish in CFB mode
229 bf-ecb Blowfish in ECB mode
230 bf-ofb Blowfish in OFB mode
232 cast-cbc CAST in CBC mode
233 cast Alias for cast-cbc
234 cast5-cbc CAST5 in CBC mode
235 cast5-cfb CAST5 in CFB mode
236 cast5-ecb CAST5 in ECB mode
237 cast5-ofb CAST5 in OFB mode
239 des-cbc DES in CBC mode
240 des Alias for des-cbc
241 des-cfb DES in CBC mode
242 des-ofb DES in OFB mode
243 des-ecb DES in ECB mode
245 des-ede-cbc Two key triple DES EDE in CBC mode
246 des-ede Two key triple DES EDE in ECB mode
247 des-ede-cfb Two key triple DES EDE in CFB mode
248 des-ede-ofb Two key triple DES EDE in OFB mode
250 des-ede3-cbc Three key triple DES EDE in CBC mode
251 des-ede3 Three key triple DES EDE in ECB mode
252 des3 Alias for des-ede3-cbc
253 des-ede3-cfb Three key triple DES EDE CFB mode
254 des-ede3-ofb Three key triple DES EDE in OFB mode
258 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
259 gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
261 idea-cbc IDEA algorithm in CBC mode
262 idea same as idea-cbc
263 idea-cfb IDEA in CFB mode
264 idea-ecb IDEA in ECB mode
265 idea-ofb IDEA in OFB mode
267 rc2-cbc 128 bit RC2 in CBC mode
268 rc2 Alias for rc2-cbc
269 rc2-cfb 128 bit RC2 in CFB mode
270 rc2-ecb 128 bit RC2 in ECB mode
271 rc2-ofb 128 bit RC2 in OFB mode
272 rc2-64-cbc 64 bit RC2 in CBC mode
273 rc2-40-cbc 40 bit RC2 in CBC mode
279 rc5-cbc RC5 cipher in CBC mode
280 rc5 Alias for rc5-cbc
281 rc5-cfb RC5 cipher in CFB mode
282 rc5-ecb RC5 cipher in ECB mode
283 rc5-ofb RC5 cipher in OFB mode
285 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
286 aes-[128|192|256] Alias for aes-[128|192|256]-cbc
287 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
288 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
289 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
290 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
291 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
295 Just base64 encode a binary file:
297 openssl base64 -in file.bin -out file.b64
301 openssl base64 -d -in file.b64 -out file.bin
303 Encrypt a file using triple DES in CBC mode using a prompted password:
305 openssl des3 -salt -in file.txt -out file.des3
307 Decrypt a file using a supplied password:
309 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
311 Encrypt a file then base64 encode it (so it can be sent via mail for example)
312 using Blowfish in CBC mode:
314 openssl bf -a -salt -in file.txt -out file.bf
316 Base64 decode a file then decrypt it:
318 openssl bf -d -salt -a -in file.bf -out file.txt
320 Decrypt some data using a supplied 40 bit RC4 key:
322 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
326 The B<-A> option when used with large files doesn't work properly.
328 There should be an option to allow an iteration count to be included.
330 The B<enc> program only supports a fixed number of algorithms with
331 certain parameters. So if, for example, you want to use RC2 with a
332 76 bit key or RC4 with an 84 bit key you can't use this program.