cregit-Linux how code gets into the kernel

Release 4.7 crypto/twofish_generic.c

Directory: crypto
/*
 * 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); }

Contributors

PersonTokensPropCommitsCommitProp
david s. millerdavid s. miller15484.15%133.33%
herbert xuherbert xu2915.85%266.67%
Total183100.00%3100.00%

/* 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); }

Contributors

PersonTokensPropCommitsCommitProp
david s. millerdavid s. miller15484.15%133.33%
herbert xuherbert xu2915.85%266.67%
Total183100.00%3100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
david s. millerdavid s. miller1593.75%150.00%
kamalesh babulalkamalesh babulal16.25%150.00%
Total16100.00%2100.00%


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

Contributors

PersonTokensPropCommitsCommitProp
david s. millerdavid s. miller1493.33%150.00%
kamalesh babulalkamalesh babulal16.67%150.00%
Total15100.00%2100.00%

module_init(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");

Overall Contributors

PersonTokensPropCommitsCommitProp
david s. millerdavid s. miller53184.02%215.38%
herbert xuherbert xu6810.76%323.08%
joachim fritschijoachim fritschi172.69%323.08%
mathias krausemathias krause50.79%17.69%
denys vlasenkodenys vlasenko50.79%17.69%
kamalesh babulalkamalesh babulal40.63%17.69%
kees cookkees cook10.16%17.69%
james morrisjames morris10.16%17.69%
Total632100.00%13100.00%
Directory: crypto
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