4 enc - symmetric cipher routines
8 B<openssl enc -ciphername>
26 The symmetric cipher commands allow data to be encrytped or decrypted
27 using various block and stream ciphers using keys based on passwords
28 or explicitly provided. Base64 encoding or decoding can also be performed
29 either by itself or in addition to the encryption or decryption.
37 the input filename, standard input by default.
39 =item B<-out filename>
41 the output filename, standard output by default.
45 use a salt in the key derivation routines. This option should B<ALWAYS>
46 be used unless compatability with previous versions of OpenSSL or SSLeay
47 is required. This option is only present on OpenSSL versions 0.9.5 or
52 don't use a salt in the key derivation routines. This is the default for
53 compatability with previous versions of OpenSSL and SSLeay.
57 encrypt the input data: this is the default.
61 decrypt the input data.
65 base64 process the data. This means that if encryption is taking place
66 the data is base64 encoded after encryption. If decryption is set then
67 the input data is base64 decoded before being decrypted.
71 if the B<-a> option is set then base64 process the data on one line.
75 the password to derive the key from.
77 =item B<-kfile filename>
79 read the password to derive the key from the first line of B<filename>
83 the actual salt to use: this must be represented as a string comprised only
88 the actual key to use: this must be represented as a string comprised only
93 the actual IV to use: this must be represented as a string comprised only
98 print out the key and IV used.
102 print out the key and IV used then immediately exit: don't do any encryption
105 =item B<-bufsize number>
107 set the buffer size for I/O
111 debug the BIOs used for I/O.
117 The program can be called either as B<openssl ciphername> or
118 B<openssl enc -ciphername>.
120 A password will be prompted for to derive the key and IV if necessary.
122 The B<-salt> option should B<ALWAYS> be used if the key is being derived
123 from a password unless you want compatability with previous versions of
126 Without the B<-salt> option it is possible to perform efficient dictionary
127 attacks on the password and to attack stream cipher encrypted data. The reason
128 for this is that without the salt the same password always generates the same
129 encryption key. When the salt is being used the first eight bytes of the
130 encrypted data are reserved for the salt: it is generated at random when
131 encrypting a file and read from the encrypted file when it is decrypted.
133 Some of the ciphers do not have large keys and others have security
134 implications if not used correctly. A beginner is advised to just use
135 a strong block cipher in CBC mode such as bf or des3.
137 All the block ciphers use PKCS#5 padding also known as standard block
138 padding: this allows a rudimentary integrity or password check to be
139 performed. However since the chance of random data passing the test is
140 better than 1 in 256 it isn't a very good test.
142 All RC2 ciphers have the same key and effective key length.
144 Blowfish and RC5 algorithms use a 128 bit key.
146 =head1 SUPPORTED CIPHERS
150 bf-cbc Blowfish in CBC mode
152 bf-cfb Blowish in CFB mode
153 bf-ecb Blowfish in ECB mode
154 bf-ofb Blowfish in OFB mode
156 cast-cbc CAST in CBC mode
157 cast Alias for cast-cbc
158 cast5-cbc CAST5 in CBC mode
159 cast5-cfb CAST5 in CFB mode
160 cast5-ecb CAST5 in ECB mode
161 cast5-ofb CAST5 in OFB mode
163 des-cbc DES in CBC mode
164 des Alias for des-cbc
165 des-cfb DES in CBC mode
166 des-ofb DES in OFB mode
167 des-ecb DES in ECB mode
169 des-ede-cbc Two key triple DES EDE in CBC mode
170 des-ede Alias for des-ede
171 des-ede-cfb Two key triple DES EDE in CFB mode
172 des-ede-ofb Two key triple DES EDE in OFB mode
174 des-ede3-cbc Three key triple DES EDE in CBC mode
175 des-ede3 Alias for des-ede3-cbc
176 des3 Alias for des-ede3-cbc
177 des-ede3-cfb Three key triple DES EDE CFB mode
178 des-ede3-ofb Three key triple DES EDE in OFB mode
182 idea-cbc IDEA algorithm in CBC mode
183 idea same as idea-cbc
184 idea-cfb IDEA in CFB mode
185 idea-ecb IDEA in ECB mode
186 idea-ofb IDEA in OFB mode
188 rc2-cbc 128 bit RC2 in CBC mode
189 rc2 Alias for rc2-cbc
190 rc2-cfb 128 bit RC2 in CBC mode
191 rc2-ecb 128 bit RC2 in CBC mode
192 rc2-ofb 128 bit RC2 in CBC mode
193 rc2-64-cbc 64 bit RC2 in CBC mode
194 rc2-40-cbc 40 bit RC2 in CBC mode
200 rc5-cbc RC5 cipher in CBC mode
201 rc5 Alias for rc5-cbc
202 rc5-cfb RC5 cipher in CBC mode
203 rc5-ecb RC5 cipher in CBC mode
204 rc5-ofb RC5 cipher in CBC mode
208 Just base64 encode a binary file:
210 openssl base64 -in file.bin -out file.b64
214 openssl base64 -d -in file.b64 -out file.bin
216 Encrypt a file using triple DES in CBC mode using a prompted password:
218 openssl des3 -salt -in file.txt -out file.des3
220 Decrypt a file using a supplied password:
222 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
224 Encrypt a file then base64 encode it (so it can be sent via mail for example)
225 using Blowfish in CBC mode:
227 openssl bf -a -salt -in file.txt -out file.bf
229 Base64 decode a file then decrypt it:
231 openssl bf -d -salt -a -in file.bf -out file.txt
233 Decrypt some data using a supplied 40 bit RC4 key:
235 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
239 The B<-A> option when used with large files doesn't work properly.
241 There should be an option to allow an iteration count to be included.
243 Like the EVP library the B<enc> program only supports a fixed number of
244 algorithms with certain parameters. So if, for example, you want to use RC2
245 with a 76 bit key or RC4 with an 84 bit key you can't use this program.