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 unless you want compatability
123 with previous versions of OpenSSL and SSLeay.
125 Without the B<-salt> option it is possible to perform efficient dictionary
126 attacks on the password and to attack stream cipher encrypted data. The reason
127 for this is that without the salt the same password always generates the same
128 encryption key. When the salt is being used the first eight bytes of the
129 encrypted data are reserved for the salt: it is generated at random when
130 encrypting a file and read from the encrypted file when it is decrypted.
132 Some of the ciphers do not have large keys and others have security
133 implications if not used correctly. A beginner is advised to just use
134 a strong block cipher in CBC mode such as bf or des3.
136 All the block ciphers use PKCS#5 padding also known as standard block
137 padding: this allows a rudimentary integrity or password check to be
138 performed. However since the chance of random data passing the test is
139 better than 1 in 256 it isn't a very good test.
141 All RC2 ciphers have the same key and effective key length.
143 Blowfish and RC5 algorithms use a 128 bit key.
145 =head1 SUPPORTED CIPHERS
149 bf-cbc Blowfish in CBC mode
151 bf-cfb Blowish in CFB mode
152 bf-ecb Blowfish in ECB mode
153 bf-ofb Blowfish in OFB mode
155 cast-cbc CAST in CBC mode
156 cast Alias for cast-cbc
157 cast5-cbc CAST5 in CBC mode
158 cast5-cfb CAST5 in CFB mode
159 cast5-ecb CAST5 in ECB mode
160 cast5-ofb CAST5 in OFB mode
162 des-cbc DES in CBC mode
163 des Alias for des-cbc
164 des-cfb DES in CBC mode
165 des-ofb DES in OFB mode
166 des-ecb DES in ECB mode
168 des-ede-cbc Two key triple DES EDE in CBC mode
169 des-ede Alias for des-ede
170 des-ede-cfb Two key triple DES EDE in CFB mode
171 des-ede-ofb Two key triple DES EDE in OFB mode
173 des-ede3-cbc Three key triple DES EDE in CBC mode
174 des-ede3 Alias for des-ede3-cbc
175 des3 Alias for des-ede3-cbc
176 des-ede3-cfb Three key triple DES EDE CFB mode
177 des-ede3-ofb Three key triple DES EDE in OFB mode
181 idea-cbc IDEA algorithm in CBC mode
182 idea same as idea-cbc
183 idea-cfb IDEA in CFB mode
184 idea-ecb IDEA in ECB mode
185 idea-ofb IDEA in OFB mode
187 rc2-cbc 128 bit RC2 in CBC mode
188 rc2 Alias for rc2-cbc
189 rc2-cfb 128 bit RC2 in CBC mode
190 rc2-ecb 128 bit RC2 in CBC mode
191 rc2-ofb 128 bit RC2 in CBC mode
192 rc2-64-cbc 64 bit RC2 in CBC mode
193 rc2-40-cbc 40 bit RC2 in CBC mode
199 rc5-cbc RC5 cipher in CBC mode
200 rc5 Alias for rc5-cbc
201 rc5-cfb RC5 cipher in CBC mode
202 rc5-ecb RC5 cipher in CBC mode
203 rc5-ofb RC5 cipher in CBC mode
207 Just base64 encode a binary file:
209 openssl base64 -in file.bin -out file.b64
213 openssl base64 -d -in file.b64 -out file.bin
215 Encrypt a file using triple DES in CBC mode using a prompted password:
217 openssl des3 -salt -in file.txt -out file.des3
219 Decrypt a file using a supplied password:
221 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
223 Encrypt a file then base64 encode it (so it can be sent via mail for example)
224 using Blowfish in CBC mode:
226 openssl bf -a -salt -in file.txt -out file.bf
228 Base64 decode a file then decrypt it:
230 openssl bf -d -salt -a -in file.bf -out file.txt
232 Decrypt some data using a supplied 40 bit RC4 key:
234 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
238 The B<-A> option when used with large files doesn't work properly.
240 There should be an option to allow an iteration count to be included.
242 Like the EVP library the B<enc> program only supports a fixed number of
243 algorithms with certain parameters. So if, for example, you want to use RC2
244 with a 76 bit key or RC4 with an 84 bit key you can't use this program.