Subversion Repositories test_project

/*

 * 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, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307

 * USA

 *

 * 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),

 * and the four 32-bit chunks of the text. */

#define ENCROUND(n, a, b, c, d) \

   x = G1 (a); y = G2 (b); \

   x += y; y += x + ctx->k[2 * (n) + 1]; \

   (c) ^= x + ctx->k[2 * (n)]; \

   (c) = ror32((c), 1); \

   (d) = rol32((d), 1) ^ y

#define DECROUND(n, a, b, c, d) \

   x = G1 (a); y = G2 (b); \

   x += y; y += x; \

   (d) ^= y + ctx->k[2 * (n) + 1]; \

   (d) = ror32((d), 1); \

   (c) = rol32((c), 1); \

   (c) ^= (x + ctx->k[2 * (n)])

/* Encryption and decryption cycles; each one is simply two Feistel rounds

 * with the 32-bit chunks re-ordered to simulate the "swap" */

#define ENCCYCLE(n) \

   ENCROUND (2 * (n), a, b, c, d); \

   ENCROUND (2 * (n) + 1, c, d, a, b)

#define DECCYCLE(n) \

   DECROUND (2 * (n) + 1, c, d, a, b); \

   DECROUND (2 * (n), a, b, c, d)

/* Macros to convert the input and output bytes into 32-bit words,

 * and simultaneously perform the whitening step.  INPACK packs word

 * number n into the variable named by x, using whitening subkey number m.

 * OUTUNPACK unpacks word number n from the variable named by x, using

 * whitening subkey number m. */

#define INPACK(n, x, m) \

   x = le32_to_cpu(src[n]) ^ ctx->w[m]

#define OUTUNPACK(n, x, m) \

   x ^= ctx->w[m]; \

   dst[n] = cpu_to_le32(x)

/* Encrypt one block.  in and out may be the same. */

static void twofish_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)

{

        struct twofish_ctx *ctx = crypto_tfm_ctx(tfm);

        const __le32 *src = (const __le32 *)in;

        __le32 *dst = (__le32 *)out;

        /* The four 32-bit chunks of the text. */

        u32 a, b, c, d;

        /* Temporaries used by the round function. */

        u32 x, y;

        /* Input whitening and packing. */

        INPACK (0, a, 0);

        INPACK (1, b, 1);

        INPACK (2, c, 2);

        INPACK (3, d, 3);

        /* Encryption Feistel cycles. */

        ENCCYCLE (0);

        ENCCYCLE (1);

        ENCCYCLE (2);

        ENCCYCLE (3);

        ENCCYCLE (4);

        ENCCYCLE (5);

        ENCCYCLE (6);

        ENCCYCLE (7);

        /* Output whitening and unpacking. */

        OUTUNPACK (0, c, 4);

        OUTUNPACK (1, d, 5);

        OUTUNPACK (2, a, 6);

        OUTUNPACK (3, b, 7);

}

/* Decrypt one block.  in and out may be the same. */

static void twofish_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)

{

        struct twofish_ctx *ctx = crypto_tfm_ctx(tfm);

        const __le32 *src = (const __le32 *)in;

        __le32 *dst = (__le32 *)out;

        /* The four 32-bit chunks of the text. */

        u32 a, b, c, d;

        /* Temporaries used by the round function. */

        u32 x, y;

        /* Input whitening and packing. */

        INPACK (0, c, 4);

        INPACK (1, d, 5);

        INPACK (2, a, 6);

        INPACK (3, b, 7);

        /* Encryption Feistel cycles. */

        DECCYCLE (7);

        DECCYCLE (6);

        DECCYCLE (5);

        DECCYCLE (4);

        DECCYCLE (3);

        DECCYCLE (2);

        DECCYCLE (1);

        DECCYCLE (0);

        /* Output whitening and unpacking. */

        OUTUNPACK (0, a, 0);

        OUTUNPACK (1, b, 1);

        OUTUNPACK (2, c, 2);

        OUTUNPACK (3, d, 3);

}

static struct crypto_alg alg = {

        .cra_name           =   "twofish",

        .cra_driver_name    =   "twofish-generic",

        .cra_priority       =   100,

        .cra_flags          =   CRYPTO_ALG_TYPE_CIPHER,

        .cra_blocksize      =   TF_BLOCK_SIZE,

        .cra_ctxsize        =   sizeof(struct twofish_ctx),

        .cra_alignmask      =   3,

        .cra_module         =   THIS_MODULE,

        .cra_list           =   LIST_HEAD_INIT(alg.cra_list),

        .cra_u              =   { .cipher = {

        .cia_min_keysize    =   TF_MIN_KEY_SIZE,

        .cia_max_keysize    =   TF_MAX_KEY_SIZE,

        .cia_setkey         =   twofish_setkey,

        .cia_encrypt        =   twofish_encrypt,

        .cia_decrypt        =   twofish_decrypt } }

};

static int __init init(void)

{

        return crypto_register_alg(&alg);

}

static void __exit fini(void)

{

        crypto_unregister_alg(&alg);

}

module_init(init);

module_exit(fini);

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION ("Twofish Cipher Algorithm");