`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_encrypt`

(

`BF_LONG
*data`,

`const BF_KEY *key`);

`void`
`BF_decrypt`

(

`BF_LONG
*data`,

`const BF_KEY *key`);

`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`);

This library implements the Blowfish cipher, which was invented and defined by

Counterpane. Note that applications should
use higher level functions such as

EVP_EncryptInit(3)
instead of calling the Blowfish functions directly.

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.

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-bit 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 implementing `modes' of Blowfish. The alternative is to use

`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.

`BF_set_key`

(),

`BF_encrypt`

(),

`BF_ecb_encrypt`

(),

`BF_cbc_encrypt`

(),

`BF_cfb64_encrypt`

(),

`BF_ofb64_encrypt`

(), and

`BF_options`

() first appeared in SSLeay
0.6.6.

`BF_decrypt`

() first appeared in
SSLeay 0.9.0. All these functions have been available since

OpenBSD 2.4.