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 one of the faster
block ciphers. It is faster than DES, and much faster
than IDEA or RC2.
Blowfish consists of a key setup phase and the actual
encryption or decryption phase.
The BF_set_key() function sets up the BF_KEY key using the
len bytes long key at data.
The BF_ecb_encrypt() function 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. The 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 BF_cbc_encrypt(), BF_cfb64_encrypt(), and
BF_ofb64_encrypt() mode functions 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. The ivec may be initialized
with anything, but the recipient needs to know
what was used, or it won't be able to decrypt. Some
programs and protocols simplify this. For example, ivec is
simply initialized to zero in SSH. The BF_cbc_encrypt()
function operates of data that is a multiple of 8 bytes
long, while the BF_cfb64_encrypt() and BF_ofb64_encrypt()
functions 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 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.
The BF_cbc_encrypt() function 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. The enc decides if encryption (BF_ENCRYPT)
or decryption (BF_DECRYPT) shall be performed. The ivec
must point at an 8 byte long initialization vector.
The BF_cfb64_encrypt() function 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. The enc decides if encryption (BF_ENCRYPT) or
decryption (BF_DECRYPT) shall be performed. The ivec must
point at an 8 byte long initialization vector. The num
must point at an integer which must be initially zero.
The BF_ofb64_encrypt() function is the OFB mode for Blowfish
with 64-bit feedback. It uses the same parameters as
the BF_cfb64_encrypt() function, which must be initialized
the same way.
The BF_encrypt() and BF_decrypt() functions are the lowest
level functions for Blowfish encryption. They encrypt or
decrypt the first 64 bits of the vector pointed by data,
using the key key. They also take each 32-bit chunk in
host-byte order, which is little-endian on little-endian
platforms and big-endian on big-endian platforms. These
functions should not be used unless you implement modes of
Blowfish. The alternative is to use the BF_ecb_encrypt()
function.
Applications should use the higher level functions, such
as EVP_EncryptInit(), instead of calling the blowfish
functions directly.
None of the functions presented here return any value.
The blowfish functions are available in all versions of
SSLeay and OpenSSL.
Files: des_modes(7)
blowfish(3)
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