crypto/twofish_generic.c - linux - Git at Google

 /*
  * 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),
  * 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_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 twofish_mod_init(void)
 {
 	return crypto_register_alg(&alg);
 }

 static void __exit twofish_mod_fini(void)
 {
 	crypto_unregister_alg(&alg);
 }

 subsys_initcall(twofish_mod_init);
 module_exit(twofish_mod_fini);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION ("Twofish Cipher Algorithm");
 MODULE_ALIAS_CRYPTO("twofish");
 MODULE_ALIAS_CRYPTO("twofish-generic");
	/*
	* 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),
	* 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_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 twofish_mod_init(void)
	{
	return crypto_register_alg(&alg);
	}

	static void __exit twofish_mod_fini(void)
	{
	crypto_unregister_alg(&alg);
	}

	subsys_initcall(twofish_mod_init);
	module_exit(twofish_mod_fini);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION ("Twofish Cipher Algorithm");
	MODULE_ALIAS_CRYPTO("twofish");
	MODULE_ALIAS_CRYPTO("twofish-generic");