5 enc - symmetric cipher routines
9 B<openssl enc -ciphername>
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.
47 the input filename, standard input by default.
49 =item B<-out filename>
51 the output filename, standard output by default.
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)>.
60 use a salt in the key derivation routines. This is the default.
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.
69 encrypt the input data: this is the default.
73 decrypt the input data.
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.
87 if the B<-a> option is set then base64 process the data on one line.
91 the password to derive the key from. This is for compatibility with previous
92 versions of OpenSSL. Superseded by the B<-pass> argument.
94 =item B<-kfile filename>
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 Superseded by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.
102 Use the specified digest to create the key from the passphrase.
103 The default algorithm is sha-256.
111 use salt (randomly generated or provide with B<-S> option) when
112 encrypting (this is the default).
116 the actual salt to use: this must be represented as a string of hex digits.
120 the actual key to use: this must be represented as a string comprised only
121 of hex digits. If only the key is specified, the IV must additionally specified
122 using the B<-iv> option. When both a key and a password are specified, the
123 key given with the B<-K> option will be used and the IV generated from the
124 password will be taken. It probably does not make much sense to specify
125 both key and password.
129 the actual IV to use: this must be represented as a string comprised only
130 of hex digits. When only the key is specified using the B<-K> option, the
131 IV must explicitly be defined. When a password is being specified using
132 one of the other options, the IV is generated from this password.
136 print out the key and IV used.
140 print out the key and IV used then immediately exit: don't do any encryption
143 =item B<-bufsize number>
145 set the buffer size for I/O
149 disable standard block padding
153 debug the BIOs used for I/O.
157 Compress or decompress clear text using zlib before encryption or after
158 decryption. This option exists only if OpenSSL with compiled with zlib
159 or zlib-dynamic option.
163 Use NULL cipher (no encryption or decryption of input).
169 The program can be called either as B<openssl ciphername> or
170 B<openssl enc -ciphername>. But the first form doesn't work with
171 engine-provided ciphers, because this form is processed before the
172 configuration file is read and any ENGINEs loaded.
174 Engines which provide entirely new encryption algorithms (such as ccgost
175 engine which provides gost89 algorithm) should be configured in the
176 configuration file. Engines, specified in the command line using -engine
177 options can only be used for hardware-assisted implementations of
178 ciphers, which are supported by OpenSSL core or other engine, specified
179 in the configuration file.
181 When enc command lists supported ciphers, ciphers provided by engines,
182 specified in the configuration files are listed too.
184 A password will be prompted for to derive the key and IV if necessary.
186 The B<-salt> option should B<ALWAYS> be used if the key is being derived
187 from a password unless you want compatibility with previous versions of
190 Without the B<-salt> option it is possible to perform efficient dictionary
191 attacks on the password and to attack stream cipher encrypted data. The reason
192 for this is that without the salt the same password always generates the same
193 encryption key. When the salt is being used the first eight bytes of the
194 encrypted data are reserved for the salt: it is generated at random when
195 encrypting a file and read from the encrypted file when it is decrypted.
197 Some of the ciphers do not have large keys and others have security
198 implications if not used correctly. A beginner is advised to just use
199 a strong block cipher in CBC mode such as bf or des3.
201 All the block ciphers normally use PKCS#5 padding also known as standard block
202 padding: this allows a rudimentary integrity or password check to be
203 performed. However since the chance of random data passing the test is
204 better than 1 in 256 it isn't a very good test.
206 If padding is disabled then the input data must be a multiple of the cipher
209 All RC2 ciphers have the same key and effective key length.
211 Blowfish and RC5 algorithms use a 128 bit key.
213 =head1 SUPPORTED CIPHERS
215 Note that some of these ciphers can be disabled at compile time
216 and some are available only if an appropriate engine is configured
217 in the configuration file. The output of the B<enc> command run with
218 unsupported options (for example B<openssl enc -help>) includes a
219 list of ciphers, supported by your version of OpenSSL, including
220 ones provided by configured engines.
222 The B<enc> program does not support authenticated encryption modes
223 like CCM and GCM. The utility does not store or retrieve the
229 bf-cbc Blowfish in CBC mode
231 bf-cfb Blowfish in CFB mode
232 bf-ecb Blowfish in ECB mode
233 bf-ofb Blowfish in OFB mode
235 cast-cbc CAST in CBC mode
236 cast Alias for cast-cbc
237 cast5-cbc CAST5 in CBC mode
238 cast5-cfb CAST5 in CFB mode
239 cast5-ecb CAST5 in ECB mode
240 cast5-ofb CAST5 in OFB mode
242 des-cbc DES in CBC mode
243 des Alias for des-cbc
244 des-cfb DES in CBC mode
245 des-ofb DES in OFB mode
246 des-ecb DES in ECB mode
248 des-ede-cbc Two key triple DES EDE in CBC mode
249 des-ede Two key triple DES EDE in ECB mode
250 des-ede-cfb Two key triple DES EDE in CFB mode
251 des-ede-ofb Two key triple DES EDE in OFB mode
253 des-ede3-cbc Three key triple DES EDE in CBC mode
254 des-ede3 Three key triple DES EDE in ECB mode
255 des3 Alias for des-ede3-cbc
256 des-ede3-cfb Three key triple DES EDE CFB mode
257 des-ede3-ofb Three key triple DES EDE in OFB mode
261 gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
262 gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
264 idea-cbc IDEA algorithm in CBC mode
265 idea same as idea-cbc
266 idea-cfb IDEA in CFB mode
267 idea-ecb IDEA in ECB mode
268 idea-ofb IDEA in OFB mode
270 rc2-cbc 128 bit RC2 in CBC mode
271 rc2 Alias for rc2-cbc
272 rc2-cfb 128 bit RC2 in CFB mode
273 rc2-ecb 128 bit RC2 in ECB mode
274 rc2-ofb 128 bit RC2 in OFB mode
275 rc2-64-cbc 64 bit RC2 in CBC mode
276 rc2-40-cbc 40 bit RC2 in CBC mode
282 rc5-cbc RC5 cipher in CBC mode
283 rc5 Alias for rc5-cbc
284 rc5-cfb RC5 cipher in CFB mode
285 rc5-ecb RC5 cipher in ECB mode
286 rc5-ofb RC5 cipher in OFB mode
288 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
289 aes[128|192|256] Alias for aes-[128|192|256]-cbc
290 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
291 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
292 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
293 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
294 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
298 Just base64 encode a binary file:
300 openssl base64 -in file.bin -out file.b64
304 openssl base64 -d -in file.b64 -out file.bin
306 Encrypt a file using triple DES in CBC mode using a prompted password:
308 openssl des3 -salt -in file.txt -out file.des3
310 Decrypt a file using a supplied password:
312 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
314 Encrypt a file then base64 encode it (so it can be sent via mail for example)
315 using Blowfish in CBC mode:
317 openssl bf -a -salt -in file.txt -out file.bf
319 Base64 decode a file then decrypt it:
321 openssl bf -d -salt -a -in file.bf -out file.txt
323 Decrypt some data using a supplied 40 bit RC4 key:
325 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
329 The B<-A> option when used with large files doesn't work properly.
331 There should be an option to allow an iteration count to be included.
333 The B<enc> program only supports a fixed number of algorithms with
334 certain parameters. So if, for example, you want to use RC2 with a
335 76 bit key or RC4 with an 84 bit key you can't use this program.
339 The default digest was changed from MD5 to SHA256 in Openssl 1.1.