BF_SET_KEY(3) | Library Functions Manual | BF_SET_KEY(3) |

`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 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-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.

June 6, 2019 | OpenBSD-current |