| /* |
| * 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_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"); |