Merge branch 'vendor/OPENSSL'
[dragonfly.git] / secure / lib / libcrypto / man / blowfish.3
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129.\" ========================================================================
130.\"
131.IX Title "blowfish 3"
18ed9402 132.TH blowfish 3 "2008-09-27" "0.9.8i" "OpenSSL"
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133.SH "NAME"
134blowfish, BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt,
135BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options \- Blowfish encryption
136.SH "SYNOPSIS"
8b0cefbb 137.IX Header "SYNOPSIS"
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138.Vb 1
139\& #include <openssl/blowfish.h>
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140.Ve
141.PP
142.Vb 1
984263bc 143\& void BF_set_key(BF_KEY *key, int len, const unsigned char *data);
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144.Ve
145.PP
146.Vb 10
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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);
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157.Ve
158.PP
159.Vb 2
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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"
8b0cefbb 164.IX Header "DESCRIPTION"
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165This library implements the Blowfish cipher, which was invented and described
166by Counterpane (see http://www.counterpane.com/blowfish.html ).
167.PP
168Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data.
169It uses a variable size key, but typically, 128 bit (16 byte) keys are
a561f9ff 170considered good for strong encryption. Blowfish can be used in the same
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171modes as \s-1DES\s0 (see \fIdes_modes\fR\|(7)). Blowfish is currently one
172of the faster block ciphers. It is quite a bit faster than \s-1DES\s0, and much
173faster than \s-1IDEA\s0 or \s-1RC2\s0.
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174.PP
175Blowfish consists of a key setup phase and the actual encryption or decryption
176phase.
177.PP
8b0cefbb 178\&\fIBF_set_key()\fR sets up the \fB\s-1BF_KEY\s0\fR \fBkey\fR using the \fBlen\fR bytes long key
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179at \fBdata\fR.
180.PP
8b0cefbb 181\&\fIBF_ecb_encrypt()\fR is the basic Blowfish encryption and decryption function.
984263bc 182It encrypts or decrypts the first 64 bits of \fBin\fR using the key \fBkey\fR,
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183putting the result in \fBout\fR. \fBenc\fR decides if encryption (\fB\s-1BF_ENCRYPT\s0\fR)
184or 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,
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186everything after the first 64 bits is ignored.
187.PP
188The mode functions \fIBF_cbc_encrypt()\fR, \fIBF_cfb64_encrypt()\fR and \fIBF_ofb64_encrypt()\fR
189all operate on variable length data. They all take an initialization vector
8b0cefbb 190\&\fBivec\fR which needs to be passed along into the next call of the same function
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191for the same message. \fBivec\fR may be initialized with anything, but the
192recipient needs to know what it was initialized with, or it won't be able
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193to 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
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197number of bytes (the amount does not have to be an exact multiple of 8). The
198purpose of the latter two is to simulate stream ciphers, and therefore, they
199need the parameter \fBnum\fR, which is a pointer to an integer where the current
200offset in \fBivec\fR is stored between calls. This integer must be initialized
201to zero when \fBivec\fR is initialized.
202.PP
8b0cefbb 203\&\fIBF_cbc_encrypt()\fR is the Cipher Block Chaining function for Blowfish. It
984263bc 204encrypts or decrypts the 64 bits chunks of \fBin\fR using the key \fBschedule\fR,
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205putting the result in \fBout\fR. \fBenc\fR decides if encryption (\s-1BF_ENCRYPT\s0) or
206decryption (\s-1BF_DECRYPT\s0) shall be performed. \fBivec\fR must point at an 8 byte
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207long initialization vector.
208.PP
8b0cefbb 209\&\fIBF_cfb64_encrypt()\fR is the \s-1CFB\s0 mode for Blowfish with 64 bit feedback.
984263bc 210It encrypts or decrypts the bytes in \fBin\fR using the key \fBschedule\fR,
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211putting the result in \fBout\fR. \fBenc\fR decides if encryption (\fB\s-1BF_ENCRYPT\s0\fR)
212or decryption (\fB\s-1BF_DECRYPT\s0\fR) shall be performed. \fBivec\fR must point at an
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2138 byte long initialization vector. \fBnum\fR must point at an integer which must
214be initially zero.
215.PP
8b0cefbb 216\&\fIBF_ofb64_encrypt()\fR is the \s-1OFB\s0 mode for Blowfish with 64 bit feedback.
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217It uses the same parameters as \fIBF_cfb64_encrypt()\fR, which must be initialized
218the same way.
219.PP
8b0cefbb 220\&\fIBF_encrypt()\fR and \fIBF_decrypt()\fR are the lowest level functions for Blowfish
984263bc 221encryption. They encrypt/decrypt the first 64 bits of the vector pointed by
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222\&\fBdata\fR, using the key \fBkey\fR. These functions should not be used unless you
223implement 'modes' of Blowfish. The alternative is to use \fIBF_ecb_encrypt()\fR.
984263bc 224If you still want to use these functions, you should be aware that they take
8b0cefbb 225each 32\-bit chunk in host-byte order, which is little-endian on little-endian
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226platforms and big-endian on big-endian ones.
227.SH "RETURN VALUES"
8b0cefbb 228.IX Header "RETURN VALUES"
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229None of the functions presented here return any value.
230.SH "NOTE"
8b0cefbb 231.IX Header "NOTE"
984263bc 232Applications should use the higher level functions
8b0cefbb 233\&\fIEVP_EncryptInit\fR\|(3) etc. instead of calling the
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234blowfish functions directly.
235.SH "SEE ALSO"
74dab6c2 236.IX Header "SEE ALSO"
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237\&\fIdes_modes\fR\|(7)
238.SH "HISTORY"
74dab6c2 239.IX Header "HISTORY"
8b0cefbb 240The Blowfish functions are available in all versions of SSLeay and OpenSSL.