5 enc - symmetric cipher routines
9 B<openssl enc -ciphername>
28 The symmetric cipher commands allow data to be encrypted or decrypted
29 using various block and stream ciphers using keys based on passwords
30 or explicitly provided. Base64 encoding or decoding can also be performed
31 either by itself or in addition to the encryption or decryption.
39 the input filename, standard input by default.
41 =item B<-out filename>
43 the output filename, standard output by default.
47 the password source. For more information about the format of B<arg>
48 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
52 use a salt in the key derivation routines. This option should B<ALWAYS>
53 be used unless compatibility with previous versions of OpenSSL or SSLeay
54 is required. This option is only present on OpenSSL versions 0.9.5 or
59 don't use a salt in the key derivation routines. This is the default for
60 compatibility with previous versions of OpenSSL and SSLeay.
64 encrypt the input data: this is the default.
68 decrypt the input data.
72 base64 process the data. This means that if encryption is taking place
73 the data is base64 encoded after encryption. If decryption is set then
74 the input data is base64 decoded before being decrypted.
78 if the B<-a> option is set then base64 process the data on one line.
82 the password to derive the key from. This is for compatibility with previous
83 versions of OpenSSL. Superseded by the B<-pass> argument.
85 =item B<-kfile filename>
87 read the password to derive the key from the first line of B<filename>.
88 This is for computability with previous versions of OpenSSL. Superseded by
89 the B<-pass> argument.
93 the actual salt to use: this must be represented as a string comprised only
98 the actual key to use: this must be represented as a string comprised only
103 the actual IV to use: this must be represented as a string comprised only
108 print out the key and IV used.
112 print out the key and IV used then immediately exit: don't do any encryption
115 =item B<-bufsize number>
117 set the buffer size for I/O
121 debug the BIOs used for I/O.
127 The program can be called either as B<openssl ciphername> or
128 B<openssl enc -ciphername>.
130 A password will be prompted for to derive the key and IV if necessary.
132 The B<-salt> option should B<ALWAYS> be used if the key is being derived
133 from a password unless you want compatibility with previous versions of
136 Without the B<-salt> option it is possible to perform efficient dictionary
137 attacks on the password and to attack stream cipher encrypted data. The reason
138 for this is that without the salt the same password always generates the same
139 encryption key. When the salt is being used the first eight bytes of the
140 encrypted data are reserved for the salt: it is generated at random when
141 encrypting a file and read from the encrypted file when it is decrypted.
143 Some of the ciphers do not have large keys and others have security
144 implications if not used correctly. A beginner is advised to just use
145 a strong block cipher in CBC mode such as bf or des3.
147 All the block ciphers use PKCS#5 padding also known as standard block
148 padding: this allows a rudimentary integrity or password check to be
149 performed. However since the chance of random data passing the test is
150 better than 1 in 256 it isn't a very good test.
152 All RC2 ciphers have the same key and effective key length.
154 Blowfish and RC5 algorithms use a 128 bit key.
156 =head1 SUPPORTED CIPHERS
160 bf-cbc Blowfish in CBC mode
162 bf-cfb Blowfish in CFB mode
163 bf-ecb Blowfish in ECB mode
164 bf-ofb Blowfish in OFB mode
166 cast-cbc CAST in CBC mode
167 cast Alias for cast-cbc
168 cast5-cbc CAST5 in CBC mode
169 cast5-cfb CAST5 in CFB mode
170 cast5-ecb CAST5 in ECB mode
171 cast5-ofb CAST5 in OFB mode
173 des-cbc DES in CBC mode
174 des Alias for des-cbc
175 des-cfb DES in CBC mode
176 des-ofb DES in OFB mode
177 des-ecb DES in ECB mode
179 des-ede-cbc Two key triple DES EDE in CBC mode
180 des-ede Alias for des-ede
181 des-ede-cfb Two key triple DES EDE in CFB mode
182 des-ede-ofb Two key triple DES EDE in OFB mode
184 des-ede3-cbc Three key triple DES EDE in CBC mode
185 des-ede3 Alias for des-ede3-cbc
186 des3 Alias for des-ede3-cbc
187 des-ede3-cfb Three key triple DES EDE CFB mode
188 des-ede3-ofb Three key triple DES EDE in OFB mode
192 idea-cbc IDEA algorithm in CBC mode
193 idea same as idea-cbc
194 idea-cfb IDEA in CFB mode
195 idea-ecb IDEA in ECB mode
196 idea-ofb IDEA in OFB mode
198 rc2-cbc 128 bit RC2 in CBC mode
199 rc2 Alias for rc2-cbc
200 rc2-cfb 128 bit RC2 in CBC mode
201 rc2-ecb 128 bit RC2 in CBC mode
202 rc2-ofb 128 bit RC2 in CBC mode
203 rc2-64-cbc 64 bit RC2 in CBC mode
204 rc2-40-cbc 40 bit RC2 in CBC mode
210 rc5-cbc RC5 cipher in CBC mode
211 rc5 Alias for rc5-cbc
212 rc5-cfb RC5 cipher in CBC mode
213 rc5-ecb RC5 cipher in CBC mode
214 rc5-ofb RC5 cipher in CBC mode
218 Just base64 encode a binary file:
220 openssl base64 -in file.bin -out file.b64
224 openssl base64 -d -in file.b64 -out file.bin
226 Encrypt a file using triple DES in CBC mode using a prompted password:
228 openssl des3 -salt -in file.txt -out file.des3
230 Decrypt a file using a supplied password:
232 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
234 Encrypt a file then base64 encode it (so it can be sent via mail for example)
235 using Blowfish in CBC mode:
237 openssl bf -a -salt -in file.txt -out file.bf
239 Base64 decode a file then decrypt it:
241 openssl bf -d -salt -a -in file.bf -out file.txt
243 Decrypt some data using a supplied 40 bit RC4 key:
245 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
249 The B<-A> option when used with large files doesn't work properly.
251 There should be an option to allow an iteration count to be included.
253 Like the EVP library the B<enc> program only supports a fixed number of
254 algorithms with certain parameters. So if, for example, you want to use RC2
255 with a 76 bit key or RC4 with an 84 bit key you can't use this program.