5 enc - symmetric cipher routines
9 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 Print out a usage message.
52 the input filename, standard input by default.
54 =item B<-out filename>
56 the output filename, standard output by default.
60 the password source. For more information about the format of B<arg>
61 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
65 use a salt in the key derivation routines. This is the default.
69 don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
70 used except for test purposes or compatibility with ancient versions of OpenSSL.
74 encrypt the input data: this is the default.
78 decrypt the input data.
82 base64 process the data. This means that if encryption is taking place
83 the data is base64 encoded after encryption. If decryption is set then
84 the input data is base64 decoded before being decrypted.
92 if the B<-a> option is set then base64 process the data on one line.
96 the password to derive the key from. This is for compatibility with previous
97 versions of OpenSSL. Superseded by the B<-pass> argument.
99 =item B<-kfile filename>
101 read the password to derive the key from the first line of B<filename>.
102 This is for compatibility with previous versions of OpenSSL. Superseded by
103 the B<-pass> argument.
107 Use the specified digest to create the key from the passphrase.
108 The default algorithm is sha-256.
116 use salt (randomly generated or provide with B<-S> option) when
117 encrypting (this is the default).
121 the actual salt to use: this must be represented as a string of hex digits.
125 the actual key to use: this must be represented as a string comprised only
126 of hex digits. If only the key is specified, the IV must additionally specified
127 using the B<-iv> option. When both a key and a password are specified, the
128 key given with the B<-K> option will be used and the IV generated from the
129 password will be taken. It probably does not make much sense to specify
130 both key and password.
134 the actual IV to use: this must be represented as a string comprised only
135 of hex digits. When only the key is specified using the B<-K> option, the
136 IV must explicitly be defined. When a password is being specified using
137 one of the other options, the IV is generated from this password.
141 print out the key and IV used.
145 print out the key and IV used then immediately exit: don't do any encryption
148 =item B<-bufsize number>
150 set the buffer size for I/O
154 disable standard block padding
158 debug the BIOs used for I/O.
162 Compress or decompress clear text using zlib before encryption or after
163 decryption. This option exists only if OpenSSL with compiled with zlib
164 or zlib-dynamic option.
168 Use NULL cipher (no encryption or decryption of input).
174 The program can be called either as B<openssl ciphername> or
175 B<openssl enc -ciphername>. But the first form doesn't work with
176 engine-provided ciphers, because this form is processed before the
177 configuration file is read and any ENGINEs loaded.
179 Engines which provide entirely new encryption algorithms (such as ccgost
180 engine which provides gost89 algorithm) should be configured in the
181 configuration file. Engines, specified in the command line using -engine
182 options can only be used for hardware-assisted implementations of
183 ciphers, which are supported by OpenSSL core or other engine, specified
184 in the configuration file.
186 When enc command lists supported ciphers, ciphers provided by engines,
187 specified in the configuration files are listed too.
189 A password will be prompted for to derive the key and IV if necessary.
191 The B<-salt> option should B<ALWAYS> be used if the key is being derived
192 from a password unless you want compatibility with previous versions of
195 Without the B<-salt> option it is possible to perform efficient dictionary
196 attacks on the password and to attack stream cipher encrypted data. The reason
197 for this is that without the salt the same password always generates the same
198 encryption key. When the salt is being used the first eight bytes of the
199 encrypted data are reserved for the salt: it is generated at random when
200 encrypting a file and read from the encrypted file when it is decrypted.
202 Some of the ciphers do not have large keys and others have security
203 implications if not used correctly. A beginner is advised to just use
204 a strong block cipher in CBC mode such as bf or des3.
206 All the block ciphers normally use PKCS#5 padding also known as standard block
207 padding: this allows a rudimentary integrity or password check to be
208 performed. However since the chance of random data passing the test is
209 better than 1 in 256 it isn't a very good test.
211 If padding is disabled then the input data must be a multiple of the cipher
214 All RC2 ciphers have the same key and effective key length.
216 Blowfish and RC5 algorithms use a 128 bit key.
218 =head1 SUPPORTED CIPHERS
220 Note that some of these ciphers can be disabled at compile time
221 and some are available only if an appropriate engine is configured
222 in the configuration file. The output of the B<enc> command run with
223 unsupported options (for example B<openssl enc -help>) includes a
224 list of ciphers, supported by your version of OpenSSL, including
225 ones provided by configured engines.
227 The B<enc> program does not support authenticated encryption modes
228 like CCM and GCM. The utility does not store or retrieve the
234 bf-cbc Blowfish in CBC mode
236 bf-cfb Blowfish in CFB mode
237 bf-ecb Blowfish in ECB mode
238 bf-ofb Blowfish in OFB mode
240 cast-cbc CAST in CBC mode
241 cast Alias for cast-cbc
242 cast5-cbc CAST5 in CBC mode
243 cast5-cfb CAST5 in CFB mode
244 cast5-ecb CAST5 in ECB mode
245 cast5-ofb CAST5 in OFB mode
247 des-cbc DES in CBC mode
248 des Alias for des-cbc
249 des-cfb DES in CBC mode
250 des-ofb DES in OFB mode
251 des-ecb DES in ECB mode
253 des-ede-cbc Two key triple DES EDE in CBC mode
254 des-ede Two key triple DES EDE in ECB mode
255 des-ede-cfb Two key triple DES EDE in CFB mode
256 des-ede-ofb Two key triple DES EDE in OFB mode
258 des-ede3-cbc Three key triple DES EDE in CBC mode
259 des-ede3 Three key triple DES EDE in ECB mode
260 des3 Alias for des-ede3-cbc
261 des-ede3-cfb Three key triple DES EDE CFB mode
262 des-ede3-ofb Three key triple DES EDE in OFB mode
266 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
267 gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
269 idea-cbc IDEA algorithm in CBC mode
270 idea same as idea-cbc
271 idea-cfb IDEA in CFB mode
272 idea-ecb IDEA in ECB mode
273 idea-ofb IDEA in OFB mode
275 rc2-cbc 128 bit RC2 in CBC mode
276 rc2 Alias for rc2-cbc
277 rc2-cfb 128 bit RC2 in CFB mode
278 rc2-ecb 128 bit RC2 in ECB mode
279 rc2-ofb 128 bit RC2 in OFB mode
280 rc2-64-cbc 64 bit RC2 in CBC mode
281 rc2-40-cbc 40 bit RC2 in CBC mode
287 rc5-cbc RC5 cipher in CBC mode
288 rc5 Alias for rc5-cbc
289 rc5-cfb RC5 cipher in CFB mode
290 rc5-ecb RC5 cipher in ECB mode
291 rc5-ofb RC5 cipher in OFB mode
293 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
294 aes[128|192|256] Alias for aes-[128|192|256]-cbc
295 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
296 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
297 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
298 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
299 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
303 Just base64 encode a binary file:
305 openssl base64 -in file.bin -out file.b64
309 openssl base64 -d -in file.b64 -out file.bin
311 Encrypt a file using triple DES in CBC mode using a prompted password:
313 openssl des3 -salt -in file.txt -out file.des3
315 Decrypt a file using a supplied password:
317 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
319 Encrypt a file then base64 encode it (so it can be sent via mail for example)
320 using Blowfish in CBC mode:
322 openssl bf -a -salt -in file.txt -out file.bf
324 Base64 decode a file then decrypt it:
326 openssl bf -d -salt -a -in file.bf -out file.txt
328 Decrypt some data using a supplied 40 bit RC4 key:
330 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
334 The B<-A> option when used with large files doesn't work properly.
336 There should be an option to allow an iteration count to be included.
338 The B<enc> program only supports a fixed number of algorithms with
339 certain parameters. So if, for example, you want to use RC2 with a
340 76 bit key or RC4 with an 84 bit key you can't use this program.
344 The default digest was changed from MD5 to SHA256 in Openssl 1.1.