.\" $OpenBSD: BF_set_key.3,v 1.12 2023/08/05 18:27:55 jmc Exp $ .\" OpenSSL 99d63d46 Jul 19 09:27:53 2016 -0400 .\" .\" This file was written by Richard Levitte . .\" Copyright (c) 2000, 2002, 2005, 2014, 2016 The OpenSSL Project. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. 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IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: August 5 2023 $ .Dt BF_SET_KEY 3 .Os .Sh NAME .Nm BF_set_key , .Nm BF_encrypt , .Nm BF_decrypt , .Nm BF_ecb_encrypt , .Nm BF_cbc_encrypt , .Nm BF_cfb64_encrypt , .Nm BF_ofb64_encrypt .Nd Blowfish encryption .Sh SYNOPSIS .In openssl/blowfish.h .Ft void .Fo BF_set_key .Fa "BF_KEY *key" .Fa "int len" .Fa "const unsigned char *data" .Fc .Ft void .Fo BF_encrypt .Fa "BF_LONG *data" .Fa "const BF_KEY *key" .Fc .Ft void .Fo BF_decrypt .Fa "BF_LONG *data" .Fa "const BF_KEY *key" .Fc .Ft void .Fo BF_ecb_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "BF_KEY *key" .Fa "int enc" .Fc .Ft void .Fo BF_cbc_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "BF_KEY *schedule" .Fa "unsigned char *ivec" .Fa "int enc" .Fc .Ft void .Fo BF_cfb64_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "BF_KEY *schedule" .Fa "unsigned char *ivec" .Fa "int *num" .Fa "int enc" .Fc .Ft void .Fo BF_ofb64_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "BF_KEY *schedule" .Fa "unsigned char *ivec" .Fa "int *num" .Fc .Sh DESCRIPTION This library implements the Blowfish cipher, which was invented and defined by .An Counterpane . Note that applications should use higher level functions such as .Xr EVP_EncryptInit 3 instead of calling the Blowfish functions directly. .Pp Blowfish is a block cipher that operates on 64-bit (8 byte) blocks of data. It uses a variable size key, but typically, 128-bit (16 byte) keys are considered good for strong encryption. Blowfish can be used in the same modes as DES and is currently one of the faster block ciphers. It is quite a bit faster than DES, and much faster than IDEA or RC2. .Pp Blowfish consists of a key setup phase and the actual encryption or decryption phase. .Pp .Fn BF_set_key sets up the .Vt BF_KEY .Fa key using the .Fa len bytes long key at .Fa data . .Pp .Fn BF_ecb_encrypt is the basic Blowfish encryption and decryption function. It encrypts or decrypts the first 64 bits of .Fa in using the key .Fa key , putting the result in .Fa out . .Fa enc decides if encryption .Pq Dv BF_ENCRYPT or decryption .Pq Dv BF_DECRYPT shall be performed. The vector pointed at by .Fa in and .Fa out must be 64 bits in length, no less. If they are larger, everything after the first 64 bits is ignored. .Pp The mode functions .Fn BF_cbc_encrypt , .Fn BF_cfb64_encrypt , and .Fn BF_ofb64_encrypt all operate on variable length data. They all take an initialization vector .Fa ivec which needs to be passed along into the next call of the same function for the same message. .Fa ivec may be initialized with anything, but the recipient needs to know what it was initialized with, or it won't be able to decrypt. Some programs and protocols simplify this, like SSH, where .Fa ivec is simply initialized to zero. .Fn BF_cbc_encrypt operates on data that is a multiple of 8 bytes long, while .Fn BF_cfb64_encrypt and .Fn BF_ofb64_encrypt are used to encrypt a variable number of bytes (the amount does not have to be an exact multiple of 8). The purpose of the latter two is to simulate stream ciphers and, therefore, they need the parameter .Fa num , which is a pointer to an integer where the current offset in .Fa ivec is stored between calls. This integer must be initialized to zero when .Fa ivec is initialized. .Pp .Fn BF_cbc_encrypt is the Cipher Block Chaining function for Blowfish. It encrypts or decrypts the 64-bit chunks of .Fa in using the key .Fa schedule , putting the result in .Fa out . .Fa enc decides if encryption .Pq Dv BF_ENCRYPT or decryption .Pq Dv BF_DECRYPT shall be performed. .Fa ivec must point at an 8-byte long initialization vector. .Pp .Fn BF_cfb64_encrypt is the CFB mode for Blowfish with 64-bit feedback. It encrypts or decrypts the bytes in .Fa in using the key .Fa schedule , putting the result in .Fa out . .Fa enc decides if encryption .Pq Dv BF_ENCRYPT or decryption .Pq Dv BF_DECRYPT shall be performed. .Fa ivec must point at an 8-byte long initialization vector. .Fa num must point at an integer which must be initially zero. .Pp .Fn BF_ofb64_encrypt is the OFB mode for Blowfish with 64-bit feedback. It uses the same parameters as .Fn BF_cfb64_encrypt , which must be initialized the same way. .Pp .Fn BF_encrypt and .Fn BF_decrypt are the lowest level functions for Blowfish encryption. They encrypt/decrypt the first 64 bits of the vector pointed by .Fa data , using the key .Fa key . These functions should not be used unless implementing `modes' of Blowfish. The alternative is to use .Fn BF_ecb_encrypt . Be aware that these functions take each 32-bit chunk in host-byte order, which is little-endian on little-endian platforms and big-endian on big-endian ones. .Sh SEE ALSO .Xr EVP_EncryptInit 3 .Sh HISTORY .Fn BF_set_key , .Fn BF_encrypt , .Fn BF_ecb_encrypt , .Fn BF_cbc_encrypt , .Fn BF_cfb64_encrypt , and .Fn BF_ofb64_encrypt first appeared in SSLeay 0.6.6. .Fn BF_decrypt first appeared in SSLeay 0.9.0. All these functions have been available since .Ox 2.4 .