197 строки
5.5 KiB
C
197 строки
5.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* 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 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/unaligned.h>
|
|
#include <crypto/algapi.h>
|
|
#include <crypto/twofish.h>
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/types.h>
|
|
#include <linux/errno.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 = get_unaligned_le32(in + (n) * 4) ^ ctx->w[m]
|
|
|
|
#define OUTUNPACK(n, x, m) \
|
|
x ^= ctx->w[m]; \
|
|
put_unaligned_le32(x, out + (n) * 4)
|
|
|
|
|
|
|
|
/* 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);
|
|
|
|
/* 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);
|
|
|
|
/* 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_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");
|