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BLOWFISH(3) Library Functions Manual BLOWFISH(3)

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

#include <blf.h>
blf_key(blf_ctx *state, const u_int8_t *key, u_int16_t keylen);
blf_enc(blf_ctx *state, u_int32_t *data, u_int16_t blocks);
blf_dec(blf_ctx *state, u_int32_t *data, u_int16_t blocks);
blf_ecb_encrypt(blf_ctx *state, u_int8_t *data, u_int32_t datalen);
blf_ecb_decrypt(blf_ctx *state, u_int8_t *data, u_int32_t datalen);
blf_cbc_encrypt(blf_ctx *state, u_int8_t *iv, u_int8_t *data, u_int32_t datalen);
blf_cbc_decrypt(blf_ctx *state, u_int8_t *iv, u_int8_t *data, u_int32_t datalen);

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.

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

Niels Provos <provos@physnet.uni-hamburg.de>
July 16, 2013 OpenBSD-5.6