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 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.

**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
32−bit chunk in host-byte order, which is
little-endian on little-endian platforms and big-endian on
big-endian ones.

None of the functions presented here return any value.

Applications
should use the higher level functions
**EVP_EncryptInit**(3) etc. instead of calling these
functions directly.

**EVP_EncryptInit**(3),
**des_modes**(7)

Copyright 2000−2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.