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.\" Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
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.\" Manual page, using -mandoc macros
.\"
.Dd February 13, 1997
.Dt BLOWFISH 3
.Os
.Sh NAME
.Nm blf_key ,
.Nm blf_enc ,
.Nm blf_dec
.Nd Blowfish encryption
.Sh SYNOPSIS
.Fd #include <blf.h>
.Ft void
.Fn blf_key "blf_ctx *state" "const u_int8_t *key" "u_int16_t keylen"
.Ft void
.Fn blf_enc "blf_ctx *state" "u_int32_t *data" "u_int16_t datalen"
.Ft void
.Fn blf_dec "blf_ctx *state" "u_int32_t *data" "u_int16_t datalen"
.Ft void
.Fn blf_ecb_encrypt "blf_ctx *state" "u_int8_t *data" "u_int32_t datalen"
.Ft void
.Fn blf_ecb_decrypt "blf_ctx *state" "u_int8_t *data" "u_int32_t datalen"
.Ft void
.Fn blf_cbc_encrypt "blf_ctx *state" "u_int8_t *iv" "u_int8_t *data" "u_int32_t datalen"
.Ft void
.Fn blf_cbc_decrypt "blf_ctx *state" "u_int8_t *iv" "u_int8_t *data" "u_int32_t datalen"
.Sh DESCRIPTION
.Pa Blowfish
is a fast unpatented block cipher designed by Bruce Schneier.
It basically consists of a 16 times iterated Feistel network.
The block size is 64 bit and the maximum key size is 448 bit.
.Pp
The
.Fn blf_key
function initializes the 4 8bit S-boxes and the 18 Subkeys with
the hexadecimal digits of Pi.
The key is used for further randomization.
The first argument to
.Fn blf_enc
is the initialized state derived from
.Fn blf_key .
The stream of 32-bit words is encrypted in Electronic Codebook
Mode (ECB) and
.Pa datalen
must be even.
.Fn blf_dec
is used for decrypting Blowfish encrypted blocks.
.Pp
The functions
.Fn blf_ecb_encrypt
and
.Fn blf_ecb_decrypt
are used for encrypting and decrypting octet streams in ECB mode.
The functions
.Fn blf_cbc_encrypt
and
.Fn blf_cbc_decrypt
are used for encrypting and decrypting octet streams in
Cipherblock Chaining Mode (CBC).
.Pp
The functions
.Fn Blowfish_initstate ,
.Fn Blowfish_expand0state ,
.Fn Blowfish_expandstate ,
.Fn Blowfish_encipher
and
.Fn Blowfish_decipher
are used for customization of the
.Pa Blowfish
cipher, e.g., for the blowfish password hashing function.
.Sh SEE ALSO
.Xr passwd 1 ,
.Xr crypt 3 ,
.Xr passwd 5
.Sh AUTHORS
.An Niels Provos Aq provos@physnet.uni-hamburg.de