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 Superseded by the B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 Superseded by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
99 of hex digits. If only the key is specified, the IV must additionally specified
100 using the B<-iv> option. When both a key and a password are specified, the
101 key given with the B<-K> option will be used and the IV generated from the
102 password will be taken. It probably does not make much sense to specify
103 both key and password.
107 the actual IV to use: this must be represented as a string comprised only
108 of hex digits. When only the key is specified using the B<-K> option, the
109 IV must explicitly be defined. When a password is being specified using
110 one of the other options, the IV is generated from this password.
114 print out the key and IV used.
118 print out the key and IV used then immediately exit: don't do any encryption
121 =item B<-bufsize number>
123 set the buffer size for I/O
127 debug the BIOs used for I/O.
133 The program can be called either as B<openssl ciphername> or
134 B<openssl enc -ciphername>.
136 A password will be prompted for to derive the key and IV if necessary.
138 The B<-salt> option should B<ALWAYS> be used if the key is being derived
139 from a password unless you want compatibility with previous versions of
142 Without the B<-salt> option it is possible to perform efficient dictionary
143 attacks on the password and to attack stream cipher encrypted data. The reason
144 for this is that without the salt the same password always generates the same
145 encryption key. When the salt is being used the first eight bytes of the
146 encrypted data are reserved for the salt: it is generated at random when
147 encrypting a file and read from the encrypted file when it is decrypted.
149 Some of the ciphers do not have large keys and others have security
150 implications if not used correctly. A beginner is advised to just use
151 a strong block cipher in CBC mode such as bf or des3.
153 All the block ciphers use PKCS#5 padding also known as standard block
154 padding: this allows a rudimentary integrity or password check to be
155 performed. However since the chance of random data passing the test is
156 better than 1 in 256 it isn't a very good test.
158 All RC2 ciphers have the same key and effective key length.
160 Blowfish and RC5 algorithms use a 128 bit key.
162 =head1 SUPPORTED CIPHERS
166 bf-cbc Blowfish in CBC mode
168 bf-cfb Blowfish in CFB mode
169 bf-ecb Blowfish in ECB mode
170 bf-ofb Blowfish in OFB mode
172 cast-cbc CAST in CBC mode
173 cast Alias for cast-cbc
174 cast5-cbc CAST5 in CBC mode
175 cast5-cfb CAST5 in CFB mode
176 cast5-ecb CAST5 in ECB mode
177 cast5-ofb CAST5 in OFB mode
179 des-cbc DES in CBC mode
180 des Alias for des-cbc
181 des-cfb DES in CBC mode
182 des-ofb DES in OFB mode
183 des-ecb DES in ECB mode
185 des-ede-cbc Two key triple DES EDE in CBC mode
186 des-ede Alias for des-ede
187 des-ede-cfb Two key triple DES EDE in CFB mode
188 des-ede-ofb Two key triple DES EDE in OFB mode
190 des-ede3-cbc Three key triple DES EDE in CBC mode
191 des-ede3 Alias for des-ede3-cbc
192 des3 Alias for des-ede3-cbc
193 des-ede3-cfb Three key triple DES EDE CFB mode
194 des-ede3-ofb Three key triple DES EDE in OFB mode
198 idea-cbc IDEA algorithm in CBC mode
199 idea same as idea-cbc
200 idea-cfb IDEA in CFB mode
201 idea-ecb IDEA in ECB mode
202 idea-ofb IDEA in OFB mode
204 rc2-cbc 128 bit RC2 in CBC mode
205 rc2 Alias for rc2-cbc
206 rc2-cfb 128 bit RC2 in CBC mode
207 rc2-ecb 128 bit RC2 in CBC mode
208 rc2-ofb 128 bit RC2 in CBC mode
209 rc2-64-cbc 64 bit RC2 in CBC mode
210 rc2-40-cbc 40 bit RC2 in CBC mode
216 rc5-cbc RC5 cipher in CBC mode
217 rc5 Alias for rc5-cbc
218 rc5-cfb RC5 cipher in CBC mode
219 rc5-ecb RC5 cipher in CBC mode
220 rc5-ofb RC5 cipher in CBC mode
224 Just base64 encode a binary file:
226 openssl base64 -in file.bin -out file.b64
230 openssl base64 -d -in file.b64 -out file.bin
232 Encrypt a file using triple DES in CBC mode using a prompted password:
234 openssl des3 -salt -in file.txt -out file.des3
236 Decrypt a file using a supplied password:
238 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
240 Encrypt a file then base64 encode it (so it can be sent via mail for example)
241 using Blowfish in CBC mode:
243 openssl bf -a -salt -in file.txt -out file.bf
245 Base64 decode a file then decrypt it:
247 openssl bf -d -salt -a -in file.bf -out file.txt
249 Decrypt some data using a supplied 40 bit RC4 key:
251 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
255 The B<-A> option when used with large files doesn't work properly.
257 There should be an option to allow an iteration count to be included.
259 Like the EVP library the B<enc> program only supports a fixed number of
260 algorithms with certain parameters. So if, for example, you want to use RC2
261 with a 76 bit key or RC4 with an 84 bit key you can't use this program.