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 is the default.
57 don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
58 used except for test purposes or compatibility with ancient versions of OpenSSL
63 encrypt the input data: this is the default.
67 decrypt the input data.
71 base64 process the data. This means that if encryption is taking place
72 the data is base64 encoded after encryption. If decryption is set then
73 the input data is base64 decoded before being decrypted.
77 if the B<-a> option is set then base64 process the data on one line.
81 the password to derive the key from. This is for compatibility with previous
82 versions of OpenSSL. Superseded by the B<-pass> argument.
84 =item B<-kfile filename>
86 read the password to derive the key from the first line of B<filename>.
87 This is for compatibility with previous versions of OpenSSL. Superseded by
88 the B<-pass> argument.
92 the actual salt to use: this must be represented as a string comprised only
97 the actual key to use: this must be represented as a string comprised only
98 of hex digits. If only the key is specified, the IV must additionally specified
99 using the B<-iv> option. When both a key and a password are specified, the
100 key given with the B<-K> option will be used and the IV generated from the
101 password will be taken. It probably does not make much sense to specify
102 both key and password.
106 the actual IV to use: this must be represented as a string comprised only
107 of hex digits. When only the key is specified using the B<-K> option, the
108 IV must explicitly be defined. When a password is being specified using
109 one of the other options, the IV is generated from this password.
113 print out the key and IV used.
117 print out the key and IV used then immediately exit: don't do any encryption
120 =item B<-bufsize number>
122 set the buffer size for I/O
126 disable standard block padding
130 debug the BIOs used for I/O.
136 The program can be called either as B<openssl ciphername> or
137 B<openssl enc -ciphername>.
139 A password will be prompted for to derive the key and IV if necessary.
141 The B<-salt> option should B<ALWAYS> be used if the key is being derived
142 from a password unless you want compatibility with previous versions of
145 Without the B<-salt> option it is possible to perform efficient dictionary
146 attacks on the password and to attack stream cipher encrypted data. The reason
147 for this is that without the salt the same password always generates the same
148 encryption key. When the salt is being used the first eight bytes of the
149 encrypted data are reserved for the salt: it is generated at random when
150 encrypting a file and read from the encrypted file when it is decrypted.
152 Some of the ciphers do not have large keys and others have security
153 implications if not used correctly. A beginner is advised to just use
154 a strong block cipher in CBC mode such as bf or des3.
156 All the block ciphers normally use PKCS#5 padding also known as standard block
157 padding: this allows a rudimentary integrity or password check to be
158 performed. However since the chance of random data passing the test is
159 better than 1 in 256 it isn't a very good test.
161 If padding is disabled then the input data must be a multiple of the cipher
164 All RC2 ciphers have the same key and effective key length.
166 Blowfish and RC5 algorithms use a 128 bit key.
168 =head1 SUPPORTED CIPHERS
172 bf-cbc Blowfish in CBC mode
174 bf-cfb Blowfish in CFB mode
175 bf-ecb Blowfish in ECB mode
176 bf-ofb Blowfish in OFB mode
178 cast-cbc CAST in CBC mode
179 cast Alias for cast-cbc
180 cast5-cbc CAST5 in CBC mode
181 cast5-cfb CAST5 in CFB mode
182 cast5-ecb CAST5 in ECB mode
183 cast5-ofb CAST5 in OFB mode
185 des-cbc DES in CBC mode
186 des Alias for des-cbc
187 des-cfb DES in CBC mode
188 des-ofb DES in OFB mode
189 des-ecb DES in ECB mode
191 des-ede-cbc Two key triple DES EDE in CBC mode
192 des-ede Two key triple DES EDE in ECB mode
193 des-ede-cfb Two key triple DES EDE in CFB mode
194 des-ede-ofb Two key triple DES EDE in OFB mode
196 des-ede3-cbc Three key triple DES EDE in CBC mode
197 des-ede3 Three key triple DES EDE in ECB mode
198 des3 Alias for des-ede3-cbc
199 des-ede3-cfb Three key triple DES EDE CFB mode
200 des-ede3-ofb Three key triple DES EDE in OFB mode
204 idea-cbc IDEA algorithm in CBC mode
205 idea same as idea-cbc
206 idea-cfb IDEA in CFB mode
207 idea-ecb IDEA in ECB mode
208 idea-ofb IDEA in OFB mode
210 rc2-cbc 128 bit RC2 in CBC mode
211 rc2 Alias for rc2-cbc
212 rc2-cfb 128 bit RC2 in CFB mode
213 rc2-ecb 128 bit RC2 in ECB mode
214 rc2-ofb 128 bit RC2 in OFB mode
215 rc2-64-cbc 64 bit RC2 in CBC mode
216 rc2-40-cbc 40 bit RC2 in CBC mode
222 rc5-cbc RC5 cipher in CBC mode
223 rc5 Alias for rc5-cbc
224 rc5-cfb RC5 cipher in CFB mode
225 rc5-ecb RC5 cipher in ECB mode
226 rc5-ofb RC5 cipher in OFB mode
228 aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
229 aes-[128|192|256] Alias for aes-[128|192|256]-cbc
230 aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
231 aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
232 aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
233 aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
234 aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
238 Just base64 encode a binary file:
240 openssl base64 -in file.bin -out file.b64
244 openssl base64 -d -in file.b64 -out file.bin
246 Encrypt a file using triple DES in CBC mode using a prompted password:
248 openssl des3 -salt -in file.txt -out file.des3
250 Decrypt a file using a supplied password:
252 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
254 Encrypt a file then base64 encode it (so it can be sent via mail for example)
255 using Blowfish in CBC mode:
257 openssl bf -a -salt -in file.txt -out file.bf
259 Base64 decode a file then decrypt it:
261 openssl bf -d -salt -a -in file.bf -out file.txt
263 Decrypt some data using a supplied 40 bit RC4 key:
265 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
269 The B<-A> option when used with large files doesn't work properly.
271 There should be an option to allow an iteration count to be included.
273 The B<enc> program only supports a fixed number of algorithms with
274 certain parameters. So if, for example, you want to use RC2 with a
275 76 bit key or RC4 with an 84 bit key you can't use this program.