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131 .IX Title "blowfish 3"
132 .TH blowfish 3 "2009-07-23" "0.9.8k" "OpenSSL"
133 .SH "NAME"
134 blowfish, BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt,
135 BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options \- Blowfish encryption
136 .SH "SYNOPSIS"
137 .IX Header "SYNOPSIS"
138 .Vb 1
139 \& #include <openssl/blowfish.h>
140 .Ve
141 .PP
142 .Vb 1
143 \& void BF_set_key(BF_KEY *key, int len, const unsigned char *data);
144 .Ve
145 .PP
146 .Vb 10
147 \& void BF_ecb_encrypt(const unsigned char *in, unsigned char *out,
148 \& BF_KEY *key, int enc);
149 \& void BF_cbc_encrypt(const unsigned char *in, unsigned char *out,
150 \& long length, BF_KEY *schedule, unsigned char *ivec, int enc);
151 \& void BF_cfb64_encrypt(const unsigned char *in, unsigned char *out,
152 \& long length, BF_KEY *schedule, unsigned char *ivec, int *num,
153 \& int enc);
154 \& void BF_ofb64_encrypt(const unsigned char *in, unsigned char *out,
155 \& long length, BF_KEY *schedule, unsigned char *ivec, int *num);
156 \& const char *BF_options(void);
157 .Ve
158 .PP
159 .Vb 2
160 \& void BF_encrypt(BF_LONG *data,const BF_KEY *key);
161 \& void BF_decrypt(BF_LONG *data,const BF_KEY *key);
162 .Ve
163 .SH "DESCRIPTION"
164 .IX Header "DESCRIPTION"
165 This library implements the Blowfish cipher, which was invented and described
166 by Counterpane (see http://www.counterpane.com/blowfish.html ).
167 .PP
168 Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data.
169 It uses a variable size key, but typically, 128 bit (16 byte) keys are
170 considered good for strong encryption. Blowfish can be used in the same
171 modes as \s-1DES\s0 (see \fIdes_modes\fR\|(7)). Blowfish is currently one
172 of the faster block ciphers. It is quite a bit faster than \s-1DES\s0, and much
173 faster than \s-1IDEA\s0 or \s-1RC2\s0.
174 .PP
175 Blowfish consists of a key setup phase and the actual encryption or decryption
176 phase.
177 .PP
178 \&\fIBF_set_key()\fR sets up the \fB\s-1BF_KEY\s0\fR \fBkey\fR using the \fBlen\fR bytes long key
179 at \fBdata\fR.
180 .PP
181 \&\fIBF_ecb_encrypt()\fR is the basic Blowfish encryption and decryption function.
182 It encrypts or decrypts the first 64 bits of \fBin\fR using the key \fBkey\fR,
183 putting the result in \fBout\fR. \fBenc\fR decides if encryption (\fB\s-1BF_ENCRYPT\s0\fR)
184 or decryption (\fB\s-1BF_DECRYPT\s0\fR) shall be performed. The vector pointed at by
185 \&\fBin\fR and \fBout\fR must be 64 bits in length, no less. If they are larger,
186 everything after the first 64 bits is ignored.
187 .PP
188 The mode functions \fIBF_cbc_encrypt()\fR, \fIBF_cfb64_encrypt()\fR and \fIBF_ofb64_encrypt()\fR
189 all operate on variable length data. They all take an initialization vector
190 \&\fBivec\fR which needs to be passed along into the next call of the same function
191 for the same message. \fBivec\fR may be initialized with anything, but the
192 recipient needs to know what it was initialized with, or it won't be able
193 to decrypt. Some programs and protocols simplify this, like \s-1SSH\s0, where
194 \&\fBivec\fR is simply initialized to zero.
195 \&\fIBF_cbc_encrypt()\fR operates on data that is a multiple of 8 bytes long, while
196 \&\fIBF_cfb64_encrypt()\fR and \fIBF_ofb64_encrypt()\fR are used to encrypt an variable
197 number of bytes (the amount does not have to be an exact multiple of 8). The
198 purpose of the latter two is to simulate stream ciphers, and therefore, they
199 need the parameter \fBnum\fR, which is a pointer to an integer where the current
200 offset in \fBivec\fR is stored between calls. This integer must be initialized
201 to zero when \fBivec\fR is initialized.
202 .PP
203 \&\fIBF_cbc_encrypt()\fR is the Cipher Block Chaining function for Blowfish. It
204 encrypts or decrypts the 64 bits chunks of \fBin\fR using the key \fBschedule\fR,
205 putting the result in \fBout\fR. \fBenc\fR decides if encryption (\s-1BF_ENCRYPT\s0) or
206 decryption (\s-1BF_DECRYPT\s0) shall be performed. \fBivec\fR must point at an 8 byte
207 long initialization vector.
208 .PP
209 \&\fIBF_cfb64_encrypt()\fR is the \s-1CFB\s0 mode for Blowfish with 64 bit feedback.
210 It encrypts or decrypts the bytes in \fBin\fR using the key \fBschedule\fR,
211 putting the result in \fBout\fR. \fBenc\fR decides if encryption (\fB\s-1BF_ENCRYPT\s0\fR)
212 or decryption (\fB\s-1BF_DECRYPT\s0\fR) shall be performed. \fBivec\fR must point at an
213 8 byte long initialization vector. \fBnum\fR must point at an integer which must
214 be initially zero.
215 .PP
216 \&\fIBF_ofb64_encrypt()\fR is the \s-1OFB\s0 mode for Blowfish with 64 bit feedback.
217 It uses the same parameters as \fIBF_cfb64_encrypt()\fR, which must be initialized
218 the same way.
219 .PP
220 \&\fIBF_encrypt()\fR and \fIBF_decrypt()\fR are the lowest level functions for Blowfish
221 encryption. They encrypt/decrypt the first 64 bits of the vector pointed by
222 \&\fBdata\fR, using the key \fBkey\fR. These functions should not be used unless you
223 implement 'modes' of Blowfish. The alternative is to use \fIBF_ecb_encrypt()\fR.
224 If you still want to use these functions, you should be aware that they take
225 each 32\-bit chunk in host-byte order, which is little-endian on little-endian
226 platforms and big-endian on big-endian ones.
227 .SH "RETURN VALUES"
228 .IX Header "RETURN VALUES"
229 None of the functions presented here return any value.
230 .SH "NOTE"
231 .IX Header "NOTE"
232 Applications should use the higher level functions
233 \&\fIEVP_EncryptInit\fR\|(3) etc. instead of calling the
234 blowfish functions directly.
235 .SH "SEE ALSO"
236 .IX Header "SEE ALSO"
237 \&\fIdes_modes\fR\|(7)
238 .SH "HISTORY"
239 .IX Header "HISTORY"
240 The Blowfish functions are available in all versions of SSLeay and OpenSSL.