linux-imx

/*

 * Twofish for CryptoAPI

 *

 * Originally Twofish for GPG

 * By Matthew Skala <mskala@ansuz.sooke.bc.ca>, July 26, 1998

 * 256-bit key length added March 20, 1999

 * Some modifications to reduce the text size by Werner Koch, April, 1998

 * Ported to the kerneli patch by Marc Mutz <Marc@Mutz.com>

 * Ported to CryptoAPI by Colin Slater <hoho@tacomeat.net>

 *

 * The original author has disclaimed all copyright interest in this

 * code and thus put it in the public domain. The subsequent authors 

 * have put this under the GNU General Public License.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 * 

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 *

 *

 * This code is a "clean room" implementation, written from the paper

 * _Twofish: A 128-Bit Block Cipher_ by Bruce Schneier, John Kelsey,

 * Doug Whiting, David Wagner, Chris Hall, and Niels Ferguson, available

 * through http://www.counterpane.com/twofish.html

 *

 * For background information on multiplication in finite fields, used for

 * the matrix operations in the key schedule, see the book _Contemporary

 * Abstract Algebra_ by Joseph A. Gallian, especially chapter 22 in the

 * Third Edition.

 */

​

#include <asm/byteorder.h>

#include <crypto/twofish.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/types.h>

#include <linux/errno.h>

#include <linux/crypto.h>

#include <linux/bitops.h>

​

/* Macros to compute the g() function in the encryption and decryption

 * rounds.  G1 is the straight g() function; G2 includes the 8-bit

 * rotation for the high 32-bit word. */

​

#define G1(a) \

     (ctx->s[0][(a) & 0xFF]) ^ (ctx->s[1][((a) >> 8) & 0xFF]) \

   ^ (ctx->s[2][((a) >> 16) & 0xFF]) ^ (ctx->s[3][(a) >> 24])

​

#define G2(b) \

     (ctx->s[1][(b) & 0xFF]) ^ (ctx->s[2][((b) >> 8) & 0xFF]) \

   ^ (ctx->s[3][((b) >> 16) & 0xFF]) ^ (ctx->s[0][(b) >> 24])

​

/* Encryption and decryption Feistel rounds.  Each one calls the two g()

 * macros, does the PHT, and performs the XOR and the appropriate bit

 * rotations.  The parameters are the round number (used to select subkeys),