5 enc - symmetric cipher routines
9 B<openssl enc -ciphername>
27 The symmetric cipher commands allow data to be encrypted or decrypted
28 using various block and stream ciphers using keys based on passwords
29 or explicitly provided. Base64 encoding or decoding can also be performed
30 either by itself or in addition to the encryption or decryption.
38 the input filename, standard input by default.
40 =item B<-out filename>
42 the output filename, standard output by default.
46 use a salt in the key derivation routines. This option should B<ALWAYS>
47 be used unless compatibility with previous versions of OpenSSL or SSLeay
48 is required. This option is only present on OpenSSL versions 0.9.5 or
53 don't use a salt in the key derivation routines. This is the default for
54 compatibility with previous versions of OpenSSL and SSLeay.
58 encrypt the input data: this is the default.
62 decrypt the input data.
66 base64 process the data. This means that if encryption is taking place
67 the data is base64 encoded after encryption. If decryption is set then
68 the input data is base64 decoded before being decrypted.
72 if the B<-a> option is set then base64 process the data on one line.
76 the password to derive the key from.
78 =item B<-kfile filename>
80 read the password to derive the key from the first line of B<filename>
84 the actual salt to use: this must be represented as a string comprised only
89 the actual key to use: this must be represented as a string comprised only
94 the actual IV to use: this must be represented as a string comprised only
99 print out the key and IV used.
103 print out the key and IV used then immediately exit: don't do any encryption
106 =item B<-bufsize number>
108 set the buffer size for I/O
112 debug the BIOs used for I/O.
118 The program can be called either as B<openssl ciphername> or
119 B<openssl enc -ciphername>.
121 A password will be prompted for to derive the key and IV if necessary.
123 The B<-salt> option should B<ALWAYS> be used if the key is being derived
124 from a password unless you want compatibility with previous versions of
127 Without the B<-salt> option it is possible to perform efficient dictionary
128 attacks on the password and to attack stream cipher encrypted data. The reason
129 for this is that without the salt the same password always generates the same
130 encryption key. When the salt is being used the first eight bytes of the
131 encrypted data are reserved for the salt: it is generated at random when
132 encrypting a file and read from the encrypted file when it is decrypted.
134 Some of the ciphers do not have large keys and others have security
135 implications if not used correctly. A beginner is advised to just use
136 a strong block cipher in CBC mode such as bf or des3.
138 All the block ciphers use PKCS#5 padding also known as standard block
139 padding: this allows a rudimentary integrity or password check to be
140 performed. However since the chance of random data passing the test is
141 better than 1 in 256 it isn't a very good test.
143 All RC2 ciphers have the same key and effective key length.
145 Blowfish and RC5 algorithms use a 128 bit key.
147 =head1 SUPPORTED CIPHERS
151 bf-cbc Blowfish in CBC mode
153 bf-cfb Blowfish in CFB mode
154 bf-ecb Blowfish in ECB mode
155 bf-ofb Blowfish in OFB mode
157 cast-cbc CAST in CBC mode
158 cast Alias for cast-cbc
159 cast5-cbc CAST5 in CBC mode
160 cast5-cfb CAST5 in CFB mode
161 cast5-ecb CAST5 in ECB mode
162 cast5-ofb CAST5 in OFB mode
164 des-cbc DES in CBC mode
165 des Alias for des-cbc
166 des-cfb DES in CBC mode
167 des-ofb DES in OFB mode
168 des-ecb DES in ECB mode
170 des-ede-cbc Two key triple DES EDE in CBC mode
171 des-ede Alias for des-ede
172 des-ede-cfb Two key triple DES EDE in CFB mode
173 des-ede-ofb Two key triple DES EDE in OFB mode
175 des-ede3-cbc Three key triple DES EDE in CBC mode
176 des-ede3 Alias for des-ede3-cbc
177 des3 Alias for des-ede3-cbc
178 des-ede3-cfb Three key triple DES EDE CFB mode
179 des-ede3-ofb Three key triple DES EDE in OFB mode
183 idea-cbc IDEA algorithm in CBC mode
184 idea same as idea-cbc
185 idea-cfb IDEA in CFB mode
186 idea-ecb IDEA in ECB mode
187 idea-ofb IDEA in OFB mode
189 rc2-cbc 128 bit RC2 in CBC mode
190 rc2 Alias for rc2-cbc
191 rc2-cfb 128 bit RC2 in CBC mode
192 rc2-ecb 128 bit RC2 in CBC mode
193 rc2-ofb 128 bit RC2 in CBC mode
194 rc2-64-cbc 64 bit RC2 in CBC mode
195 rc2-40-cbc 40 bit RC2 in CBC mode
201 rc5-cbc RC5 cipher in CBC mode
202 rc5 Alias for rc5-cbc
203 rc5-cfb RC5 cipher in CBC mode
204 rc5-ecb RC5 cipher in CBC mode
205 rc5-ofb RC5 cipher in CBC mode
209 Just base64 encode a binary file:
211 openssl base64 -in file.bin -out file.b64
215 openssl base64 -d -in file.b64 -out file.bin
217 Encrypt a file using triple DES in CBC mode using a prompted password:
219 openssl des3 -salt -in file.txt -out file.des3
221 Decrypt a file using a supplied password:
223 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
225 Encrypt a file then base64 encode it (so it can be sent via mail for example)
226 using Blowfish in CBC mode:
228 openssl bf -a -salt -in file.txt -out file.bf
230 Base64 decode a file then decrypt it:
232 openssl bf -d -salt -a -in file.bf -out file.txt
234 Decrypt some data using a supplied 40 bit RC4 key:
236 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
240 The B<-A> option when used with large files doesn't work properly.
242 There should be an option to allow an iteration count to be included.
244 Like the EVP library the B<enc> program only supports a fixed number of
245 algorithms with certain parameters. So if, for example, you want to use RC2
246 with a 76 bit key or RC4 with an 84 bit key you can't use this program.