5 enc - symmetric cipher routines
9 B<openssl enc -ciphername>
29 The symmetric cipher commands allow data to be encrypted or decrypted
30 using various block and stream ciphers using keys based on passwords
31 or explicitly provided. Base64 encoding or decoding can also be performed
32 either by itself or in addition to the encryption or decryption.
40 the input filename, standard input by default.
42 =item B<-out filename>
44 the output filename, standard output by default.
48 the password source. For more information about the format of B<arg>
49 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
53 use a salt in the key derivation routines. This option should B<ALWAYS>
54 be used unless compatibility with previous versions of OpenSSL or SSLeay
55 is required. This option is only present on OpenSSL versions 0.9.5 or
60 don't use a salt in the key derivation routines. This is the default for
61 compatibility with previous versions of OpenSSL and SSLeay.
65 encrypt the input data: this is the default.
69 decrypt the input data.
73 base64 process the data. This means that if encryption is taking place
74 the data is base64 encoded after encryption. If decryption is set then
75 the input data is base64 decoded before being decrypted.
79 if the B<-a> option is set then base64 process the data on one line.
83 the password to derive the key from. This is for compatibility with previous
84 versions of OpenSSL. Superseded by the B<-pass> argument.
86 =item B<-kfile filename>
88 read the password to derive the key from the first line of B<filename>.
89 This is for computability with previous versions of OpenSSL. Superseded by
90 the B<-pass> argument.
94 the actual salt to use: this must be represented as a string comprised only
99 the actual key to use: this must be represented as a string comprised only
104 the actual IV to use: this must be represented as a string comprised only
109 print out the key and IV used.
113 print out the key and IV used then immediately exit: don't do any encryption
116 =item B<-bufsize number>
118 set the buffer size for I/O
122 disable standard block padding
126 debug the BIOs used for I/O.
132 The program can be called either as B<openssl ciphername> or
133 B<openssl enc -ciphername>.
135 A password will be prompted for to derive the key and IV if necessary.
137 The B<-salt> option should B<ALWAYS> be used if the key is being derived
138 from a password unless you want compatibility with previous versions of
141 Without the B<-salt> option it is possible to perform efficient dictionary
142 attacks on the password and to attack stream cipher encrypted data. The reason
143 for this is that without the salt the same password always generates the same
144 encryption key. When the salt is being used the first eight bytes of the
145 encrypted data are reserved for the salt: it is generated at random when
146 encrypting a file and read from the encrypted file when it is decrypted.
148 Some of the ciphers do not have large keys and others have security
149 implications if not used correctly. A beginner is advised to just use
150 a strong block cipher in CBC mode such as bf or des3.
152 All the block ciphers normally use PKCS#5 padding also known as standard block
153 padding: this allows a rudimentary integrity or password check to be
154 performed. However since the chance of random data passing the test is
155 better than 1 in 256 it isn't a very good test.
157 If padding is disabled then the input data must be a muliple of the cipher
160 All RC2 ciphers have the same key and effective key length.
162 Blowfish and RC5 algorithms use a 128 bit key.
164 =head1 SUPPORTED CIPHERS
168 bf-cbc Blowfish in CBC mode
170 bf-cfb Blowfish in CFB mode
171 bf-ecb Blowfish in ECB mode
172 bf-ofb Blowfish in OFB mode
174 cast-cbc CAST in CBC mode
175 cast Alias for cast-cbc
176 cast5-cbc CAST5 in CBC mode
177 cast5-cfb CAST5 in CFB mode
178 cast5-ecb CAST5 in ECB mode
179 cast5-ofb CAST5 in OFB mode
181 des-cbc DES in CBC mode
182 des Alias for des-cbc
183 des-cfb DES in CBC mode
184 des-ofb DES in OFB mode
185 des-ecb DES in ECB mode
187 des-ede-cbc Two key triple DES EDE in CBC mode
188 des-ede Alias for des-ede
189 des-ede-cfb Two key triple DES EDE in CFB mode
190 des-ede-ofb Two key triple DES EDE in OFB mode
192 des-ede3-cbc Three key triple DES EDE in CBC mode
193 des-ede3 Alias for des-ede3-cbc
194 des3 Alias for des-ede3-cbc
195 des-ede3-cfb Three key triple DES EDE CFB mode
196 des-ede3-ofb Three key triple DES EDE in OFB mode
200 idea-cbc IDEA algorithm in CBC mode
201 idea same as idea-cbc
202 idea-cfb IDEA in CFB mode
203 idea-ecb IDEA in ECB mode
204 idea-ofb IDEA in OFB mode
206 rc2-cbc 128 bit RC2 in CBC mode
207 rc2 Alias for rc2-cbc
208 rc2-cfb 128 bit RC2 in CBC mode
209 rc2-ecb 128 bit RC2 in CBC mode
210 rc2-ofb 128 bit RC2 in CBC mode
211 rc2-64-cbc 64 bit RC2 in CBC mode
212 rc2-40-cbc 40 bit RC2 in CBC mode
218 rc5-cbc RC5 cipher in CBC mode
219 rc5 Alias for rc5-cbc
220 rc5-cfb RC5 cipher in CBC mode
221 rc5-ecb RC5 cipher in CBC mode
222 rc5-ofb RC5 cipher in CBC mode
226 Just base64 encode a binary file:
228 openssl base64 -in file.bin -out file.b64
232 openssl base64 -d -in file.b64 -out file.bin
234 Encrypt a file using triple DES in CBC mode using a prompted password:
236 openssl des3 -salt -in file.txt -out file.des3
238 Decrypt a file using a supplied password:
240 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
242 Encrypt a file then base64 encode it (so it can be sent via mail for example)
243 using Blowfish in CBC mode:
245 openssl bf -a -salt -in file.txt -out file.bf
247 Base64 decode a file then decrypt it:
249 openssl bf -d -salt -a -in file.bf -out file.txt
251 Decrypt some data using a supplied 40 bit RC4 key:
253 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
257 The B<-A> option when used with large files doesn't work properly.
259 There should be an option to allow an iteration count to be included.
261 The B<enc> program only supports a fixed number of algorithms with
262 certain parameters. So if, for example, you want to use RC2 with a
263 76 bit key or RC4 with an 84 bit key you can't use this program.