Merge from vendor branch OPENSSL:
[dragonfly.git] / secure / lib / libcrypto / man / blowfish.3
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124.\" ========================================================================
125.\"
126.IX Title "blowfish 3"
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127.TH blowfish 3 "2007-10-24" "0.9.8g" "OpenSSL"
128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents.
130.if n .ad l
131.nh
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132.SH "NAME"
133blowfish, BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt,
134BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options \- Blowfish encryption
135.SH "SYNOPSIS"
8b0cefbb 136.IX Header "SYNOPSIS"
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137.Vb 1
138\& #include <openssl/blowfish.h>
2eaa1526 139\&
984263bc 140\& void BF_set_key(BF_KEY *key, int len, const unsigned char *data);
2eaa1526 141\&
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142\& void BF_ecb_encrypt(const unsigned char *in, unsigned char *out,
143\& BF_KEY *key, int enc);
144\& void BF_cbc_encrypt(const unsigned char *in, unsigned char *out,
145\& long length, BF_KEY *schedule, unsigned char *ivec, int enc);
146\& void BF_cfb64_encrypt(const unsigned char *in, unsigned char *out,
147\& long length, BF_KEY *schedule, unsigned char *ivec, int *num,
148\& int enc);
149\& void BF_ofb64_encrypt(const unsigned char *in, unsigned char *out,
150\& long length, BF_KEY *schedule, unsigned char *ivec, int *num);
151\& const char *BF_options(void);
2eaa1526 152\&
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153\& void BF_encrypt(BF_LONG *data,const BF_KEY *key);
154\& void BF_decrypt(BF_LONG *data,const BF_KEY *key);
155.Ve
156.SH "DESCRIPTION"
8b0cefbb 157.IX Header "DESCRIPTION"
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158This library implements the Blowfish cipher, which was invented and described
159by Counterpane (see http://www.counterpane.com/blowfish.html ).
160.PP
161Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data.
162It uses a variable size key, but typically, 128 bit (16 byte) keys are
a561f9ff 163considered good for strong encryption. Blowfish can be used in the same
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164modes as \s-1DES\s0 (see \fIdes_modes\fR\|(7)). Blowfish is currently one
165of the faster block ciphers. It is quite a bit faster than \s-1DES\s0, and much
166faster than \s-1IDEA\s0 or \s-1RC2\s0.
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167.PP
168Blowfish consists of a key setup phase and the actual encryption or decryption
169phase.
170.PP
8b0cefbb 171\&\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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172at \fBdata\fR.
173.PP
8b0cefbb 174\&\fIBF_ecb_encrypt()\fR is the basic Blowfish encryption and decryption function.
984263bc 175It encrypts or decrypts the first 64 bits of \fBin\fR using the key \fBkey\fR,
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176putting the result in \fBout\fR. \fBenc\fR decides if encryption (\fB\s-1BF_ENCRYPT\s0\fR)
177or decryption (\fB\s-1BF_DECRYPT\s0\fR) shall be performed. The vector pointed at by
178\&\fBin\fR and \fBout\fR must be 64 bits in length, no less. If they are larger,
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179everything after the first 64 bits is ignored.
180.PP
181The mode functions \fIBF_cbc_encrypt()\fR, \fIBF_cfb64_encrypt()\fR and \fIBF_ofb64_encrypt()\fR
182all operate on variable length data. They all take an initialization vector
8b0cefbb 183\&\fBivec\fR which needs to be passed along into the next call of the same function
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184for the same message. \fBivec\fR may be initialized with anything, but the
185recipient needs to know what it was initialized with, or it won't be able
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186to decrypt. Some programs and protocols simplify this, like \s-1SSH\s0, where
187\&\fBivec\fR is simply initialized to zero.
188\&\fIBF_cbc_encrypt()\fR operates on data that is a multiple of 8 bytes long, while
189\&\fIBF_cfb64_encrypt()\fR and \fIBF_ofb64_encrypt()\fR are used to encrypt an variable
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190number of bytes (the amount does not have to be an exact multiple of 8). The
191purpose of the latter two is to simulate stream ciphers, and therefore, they
192need the parameter \fBnum\fR, which is a pointer to an integer where the current
193offset in \fBivec\fR is stored between calls. This integer must be initialized
194to zero when \fBivec\fR is initialized.
195.PP
8b0cefbb 196\&\fIBF_cbc_encrypt()\fR is the Cipher Block Chaining function for Blowfish. It
984263bc 197encrypts or decrypts the 64 bits chunks of \fBin\fR using the key \fBschedule\fR,
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198putting the result in \fBout\fR. \fBenc\fR decides if encryption (\s-1BF_ENCRYPT\s0) or
199decryption (\s-1BF_DECRYPT\s0) shall be performed. \fBivec\fR must point at an 8 byte
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200long initialization vector.
201.PP
8b0cefbb 202\&\fIBF_cfb64_encrypt()\fR is the \s-1CFB\s0 mode for Blowfish with 64 bit feedback.
984263bc 203It encrypts or decrypts the bytes in \fBin\fR using the key \fBschedule\fR,
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204putting the result in \fBout\fR. \fBenc\fR decides if encryption (\fB\s-1BF_ENCRYPT\s0\fR)
205or decryption (\fB\s-1BF_DECRYPT\s0\fR) shall be performed. \fBivec\fR must point at an
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2068 byte long initialization vector. \fBnum\fR must point at an integer which must
207be initially zero.
208.PP
8b0cefbb 209\&\fIBF_ofb64_encrypt()\fR is the \s-1OFB\s0 mode for Blowfish with 64 bit feedback.
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210It uses the same parameters as \fIBF_cfb64_encrypt()\fR, which must be initialized
211the same way.
212.PP
8b0cefbb 213\&\fIBF_encrypt()\fR and \fIBF_decrypt()\fR are the lowest level functions for Blowfish
984263bc 214encryption. They encrypt/decrypt the first 64 bits of the vector pointed by
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215\&\fBdata\fR, using the key \fBkey\fR. These functions should not be used unless you
216implement 'modes' of Blowfish. The alternative is to use \fIBF_ecb_encrypt()\fR.
984263bc 217If you still want to use these functions, you should be aware that they take
8b0cefbb 218each 32\-bit chunk in host-byte order, which is little-endian on little-endian
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219platforms and big-endian on big-endian ones.
220.SH "RETURN VALUES"
8b0cefbb 221.IX Header "RETURN VALUES"
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222None of the functions presented here return any value.
223.SH "NOTE"
8b0cefbb 224.IX Header "NOTE"
984263bc 225Applications should use the higher level functions
8b0cefbb 226\&\fIEVP_EncryptInit\fR\|(3) etc. instead of calling the
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227blowfish functions directly.
228.SH "SEE ALSO"
74dab6c2 229.IX Header "SEE ALSO"
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230\&\fIdes_modes\fR\|(7)
231.SH "HISTORY"
74dab6c2 232.IX Header "HISTORY"
8b0cefbb 233The Blowfish functions are available in all versions of SSLeay and OpenSSL.