blowfish(3)
blowfish, BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt,
BF_cbc_encrypt, BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options  Blowfish
encryption
#include <openssl/blowfish.h>
void BF_set_key(BF_KEY *key, int len, const unsigned char *data);
void BF_ecb_encrypt(const unsigned char *in, unsigned char *out,
BF_KEY *key, int enc);
void BF_cbc_encrypt(const unsigned char *in, unsigned char *out,
long length, BF_KEY *schedule, unsigned char *ivec, int enc);
void BF_cfb64_encrypt(const unsigned char *in, unsigned char *out,
long length, BF_KEY *schedule, unsigned char *ivec, int *num,
int enc);
void BF_ofb64_encrypt(const unsigned char *in, unsigned char *out,
long length, BF_KEY *schedule, unsigned char *ivec, int *num);
const char *BF_options(void);
void BF_encrypt(BF_LONG *data,const BF_KEY *key);
void BF_decrypt(BF_LONG *data,const BF_KEY *key);
This library implements the Blowfish cipher, which was invented and
described by Counterpane (see http://www.counterpane.com/blowfish.html
).
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 (see des_modes(7)). Blowfish is currently one of the faster block ciphers. It is quite a bit
faster than DES, and much faster than IDEA or RC2.
Blowfish consists of a key setup phase and the actual encryption or
decryption phase.
BF_set_key() sets up the BF_KEY key using the len bytes long key at data.
BF_ecb_encrypt() is the basic Blowfish encryption and
decryption function. It encrypts or decrypts the first 64 bits of in using the key key, putting the result in out. enc decides if encryption (BF_ENCRYPT) or decryption (BF_DECRYPT) shall be performed. The vector pointed at by
in and out must be 64 bits in length, no less. If they are larger, everything after
the first 64 bits is ignored.
The mode functions BF_cbc_encrypt(),
BF_cfb64_encrypt() and BF_ofb64_encrypt() all
operate on variable length data. They all take an initialization vector
ivec which needs to be passed along into the next call of the same function for
the same message. 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
ivec is simply initialized to zero. BF_cbc_encrypt() operates on
data that is a multiple of 8 bytes long, while
BF_cfb64_encrypt() and BF_ofb64_encrypt() are
used to encrypt an 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 num, which is a pointer to an integer where the current offset in ivec is stored between calls. This integer must be initialized to zero when ivec is initialized.
BF_cbc_encrypt() is the Cipher Block Chaining function for
Blowfish. It encrypts or decrypts the 64 bits chunks of in using the key schedule, putting the result in out. enc decides if encryption (BF_ENCRYPT) or decryption (BF_DECRYPT) shall be
performed. ivec must point at an 8 byte long initialization vector.
BF_cfb64_encrypt() is the CFB mode for Blowfish with 64 bit
feedback. It encrypts or decrypts the bytes in in using the key schedule, putting the result in out. enc decides if encryption (BF_ENCRYPT) or decryption (BF_DECRYPT) shall be performed. ivec must point at an 8 byte long initialization vector. num must point at an integer which must be initially zero.
BF_ofb64_encrypt() is the OFB mode for Blowfish with 64 bit
feedback. It uses the same parameters as BF_cfb64_encrypt(),
which must be initialized the same way.
BF_encrypt() and BF_decrypt() are the lowest
level functions for Blowfish encryption. They encrypt/decrypt the first 64
bits of the vector pointed by
data, using the key key. These functions should not be used unless you implement 'modes' of
Blowfish. The alternative is to use BF_ecb_encrypt(). If you
still want to use these functions, you should be aware that they take each
32bit chunk in hostbyte order, which is littleendian on littleendian
platforms and bigendian on bigendian ones.
None of the functions presented here return any value.
Applications should use the higher level functions
EVP_EncryptInit(3) etc. instead of calling the blowfish functions directly.
des_modes(7)
The Blowfish functions are available in all versions of SSLeay and OpenSSL.
