BLF_KEY(3) | Library Functions Manual | BLF_KEY(3)

# NAME

`blf_key`, `blf_enc`, `blf_dec`, `blf_ecb_encrypt`, `blf_ecb_decrypt`, `blf_cbc_encrypt`, `blf_cbc_decrypt` — Blowfish encryption

# SYNOPSIS

`#include <blf.h>`

void
`blf_key`(blf_ctx *state, const u_int8_t *key, u_int16_t keylen);

void
`blf_enc`(blf_ctx *state, u_int32_t *data, u_int16_t blocks);

void
`blf_dec`(blf_ctx *state, u_int32_t *data, u_int16_t blocks);

void
`blf_ecb_encrypt`(blf_ctx *state, u_int8_t *data, u_int32_t datalen);

void
`blf_ecb_decrypt`(blf_ctx *state, u_int8_t *data, u_int32_t datalen);

void
`blf_cbc_encrypt`(blf_ctx *state, u_int8_t *iv, u_int8_t *data, u_int32_t datalen);

void
`blf_cbc_decrypt`(blf_ctx *state, u_int8_t *iv, u_int8_t *data, u_int32_t datalen);

# DESCRIPTION

Blowfish is a fast unpatented block cipher designed by Bruce Schneier. It basically consists of a 16-round Feistel network. The block size is 64 bits and the maximum key size is 448 bits.

The `blf_key`() function initializes the 4 8-bit S-boxes and the 18 Subkeys with the hexadecimal digits of Pi. The key is used for further randomization. The first argument to `blf_enc`() is the initialized state derived from `blf_key`(). The stream of 32-bit words is encrypted in Electronic Codebook Mode (ECB) and blocks is the number of 64-bit blocks in the stream. `blf_dec`() is used for decrypting Blowfish encrypted blocks.

The functions `blf_ecb_encrypt`() and `blf_ecb_decrypt`() are used for encrypting and decrypting octet streams in ECB mode. The functions `blf_cbc_encrypt`() and `blf_cbc_decrypt`() are used for encrypting and decrypting octet streams in Cipherblock Chaining Mode (CBC). For these functions datalen specifies the number of octets of data to encrypt or decrypt. It must be a multiple of 8 (64-bit block). The initialisation vector iv points to an 8-byte buffer.

# SEE ALSO

passwd(1), crypt(3), passwd(5)

# AUTHORS

Niels Provos <provos@physnet.uni-hamburg.de>

November 29, 2021 | Debian