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| 131 | .rm #[ #] #H #V #F C |
| 132 | .\" ======================================================================== |
| 133 | .\" |
| 134 | .IX Title "blowfish 3" |
| 135 | .TH blowfish 3 "2009-01-11" "0.9.8j" "OpenSSL" |
| 136 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
| 137 | .\" way too many mistakes in technical documents. |
| 138 | .if n .ad l |
| 139 | .nh |
| 140 | .SH "NAME" |
| 141 | blowfish, BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt, |
| 142 | BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options \- Blowfish encryption |
| 143 | .SH "SYNOPSIS" |
| 144 | .IX Header "SYNOPSIS" |
| 145 | .Vb 1 |
| 146 | \& #include <openssl/blowfish.h> |
| 147 | \& |
| 148 | \& void BF_set_key(BF_KEY *key, int len, const unsigned char *data); |
| 149 | \& |
| 150 | \& void BF_ecb_encrypt(const unsigned char *in, unsigned char *out, |
| 151 | \& BF_KEY *key, int enc); |
| 152 | \& void BF_cbc_encrypt(const unsigned char *in, unsigned char *out, |
| 153 | \& long length, BF_KEY *schedule, unsigned char *ivec, int enc); |
| 154 | \& void BF_cfb64_encrypt(const unsigned char *in, unsigned char *out, |
| 155 | \& long length, BF_KEY *schedule, unsigned char *ivec, int *num, |
| 156 | \& int enc); |
| 157 | \& void BF_ofb64_encrypt(const unsigned char *in, unsigned char *out, |
| 158 | \& long length, BF_KEY *schedule, unsigned char *ivec, int *num); |
| 159 | \& const char *BF_options(void); |
| 160 | \& |
| 161 | \& void BF_encrypt(BF_LONG *data,const BF_KEY *key); |
| 162 | \& void BF_decrypt(BF_LONG *data,const BF_KEY *key); |
| 163 | .Ve |
| 164 | .SH "DESCRIPTION" |
| 165 | .IX Header "DESCRIPTION" |
| 166 | This library implements the Blowfish cipher, which was invented and described |
| 167 | by Counterpane (see http://www.counterpane.com/blowfish.html ). |
| 168 | .PP |
| 169 | Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data. |
| 170 | It uses a variable size key, but typically, 128 bit (16 byte) keys are |
| 171 | considered good for strong encryption. Blowfish can be used in the same |
| 172 | modes as \s-1DES\s0 (see \fIdes_modes\fR\|(7)). Blowfish is currently one |
| 173 | of the faster block ciphers. It is quite a bit faster than \s-1DES\s0, and much |
| 174 | faster than \s-1IDEA\s0 or \s-1RC2\s0. |
| 175 | .PP |
| 176 | Blowfish consists of a key setup phase and the actual encryption or decryption |
| 177 | phase. |
| 178 | .PP |
| 179 | \&\fIBF_set_key()\fR sets up the \fB\s-1BF_KEY\s0\fR \fBkey\fR using the \fBlen\fR bytes long key |
| 180 | at \fBdata\fR. |
| 181 | .PP |
| 182 | \&\fIBF_ecb_encrypt()\fR is the basic Blowfish encryption and decryption function. |
| 183 | It encrypts or decrypts the first 64 bits of \fBin\fR using the key \fBkey\fR, |
| 184 | putting the result in \fBout\fR. \fBenc\fR decides if encryption (\fB\s-1BF_ENCRYPT\s0\fR) |
| 185 | or decryption (\fB\s-1BF_DECRYPT\s0\fR) shall be performed. The vector pointed at by |
| 186 | \&\fBin\fR and \fBout\fR must be 64 bits in length, no less. If they are larger, |
| 187 | everything after the first 64 bits is ignored. |
| 188 | .PP |
| 189 | The mode functions \fIBF_cbc_encrypt()\fR, \fIBF_cfb64_encrypt()\fR and \fIBF_ofb64_encrypt()\fR |
| 190 | all operate on variable length data. They all take an initialization vector |
| 191 | \&\fBivec\fR which needs to be passed along into the next call of the same function |
| 192 | for the same message. \fBivec\fR may be initialized with anything, but the |
| 193 | recipient needs to know what it was initialized with, or it won't be able |
| 194 | to decrypt. Some programs and protocols simplify this, like \s-1SSH\s0, where |
| 195 | \&\fBivec\fR is simply initialized to zero. |
| 196 | \&\fIBF_cbc_encrypt()\fR operates on data that is a multiple of 8 bytes long, while |
| 197 | \&\fIBF_cfb64_encrypt()\fR and \fIBF_ofb64_encrypt()\fR are used to encrypt an variable |
| 198 | number of bytes (the amount does not have to be an exact multiple of 8). The |
| 199 | purpose of the latter two is to simulate stream ciphers, and therefore, they |
| 200 | need the parameter \fBnum\fR, which is a pointer to an integer where the current |
| 201 | offset in \fBivec\fR is stored between calls. This integer must be initialized |
| 202 | to zero when \fBivec\fR is initialized. |
| 203 | .PP |
| 204 | \&\fIBF_cbc_encrypt()\fR is the Cipher Block Chaining function for Blowfish. It |
| 205 | encrypts or decrypts the 64 bits chunks of \fBin\fR using the key \fBschedule\fR, |
| 206 | putting the result in \fBout\fR. \fBenc\fR decides if encryption (\s-1BF_ENCRYPT\s0) or |
| 207 | decryption (\s-1BF_DECRYPT\s0) shall be performed. \fBivec\fR must point at an 8 byte |
| 208 | long initialization vector. |
| 209 | .PP |
| 210 | \&\fIBF_cfb64_encrypt()\fR is the \s-1CFB\s0 mode for Blowfish with 64 bit feedback. |
| 211 | It encrypts or decrypts the bytes in \fBin\fR using the key \fBschedule\fR, |
| 212 | putting the result in \fBout\fR. \fBenc\fR decides if encryption (\fB\s-1BF_ENCRYPT\s0\fR) |
| 213 | or decryption (\fB\s-1BF_DECRYPT\s0\fR) shall be performed. \fBivec\fR must point at an |
| 214 | 8 byte long initialization vector. \fBnum\fR must point at an integer which must |
| 215 | be initially zero. |
| 216 | .PP |
| 217 | \&\fIBF_ofb64_encrypt()\fR is the \s-1OFB\s0 mode for Blowfish with 64 bit feedback. |
| 218 | It uses the same parameters as \fIBF_cfb64_encrypt()\fR, which must be initialized |
| 219 | the same way. |
| 220 | .PP |
| 221 | \&\fIBF_encrypt()\fR and \fIBF_decrypt()\fR are the lowest level functions for Blowfish |
| 222 | encryption. They encrypt/decrypt the first 64 bits of the vector pointed by |
| 223 | \&\fBdata\fR, using the key \fBkey\fR. These functions should not be used unless you |
| 224 | implement 'modes' of Blowfish. The alternative is to use \fIBF_ecb_encrypt()\fR. |
| 225 | If you still want to use these functions, you should be aware that they take |
| 226 | each 32\-bit chunk in host-byte order, which is little-endian on little-endian |
| 227 | platforms and big-endian on big-endian ones. |
| 228 | .SH "RETURN VALUES" |
| 229 | .IX Header "RETURN VALUES" |
| 230 | None of the functions presented here return any value. |
| 231 | .SH "NOTE" |
| 232 | .IX Header "NOTE" |
| 233 | Applications should use the higher level functions |
| 234 | \&\fIEVP_EncryptInit\fR\|(3) etc. instead of calling the |
| 235 | blowfish functions directly. |
| 236 | .SH "SEE ALSO" |
| 237 | .IX Header "SEE ALSO" |
| 238 | \&\fIdes_modes\fR\|(7) |
| 239 | .SH "HISTORY" |
| 240 | .IX Header "HISTORY" |
| 241 | The Blowfish functions are available in all versions of SSLeay and OpenSSL. |