crypto: twofish: Rename twofish to twofish_generic and add an alias

This fixes the broken autoloading of the corresponding twofish assembler
ciphers on x86 and x86_64 if they are available. The module name of the
generic implementation was in conflict with the alias in the assembler
modules. The generic twofish c implementation is renamed to
twofish_generic according to the other algorithms with assembler
implementations and an module alias is added for 'twofish'. You can now
load 'twofish' giving you the best implementation by priority,
'twofish-generic' to get the c implementation or 'twofish-asm' to get
the assembler version of cipher.

Signed-off-by: Joachim Fritschi <jfritschi@freenet.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 215 insertions, 0 deletions

diff --git a/crypto/twofish_generic.c b/crypto/twofish_generic.c
new file mode 100644
index 0000000..1f07b84
--- /dev/null
+++ b/crypto/twofish_generic.c
@@ -0,0 +1,215 @@
+/*
+ * 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 twofish_mod_init(void)
+{
+	return crypto_register_alg(&alg);
+}
+
+static void __exit twofish_mod_fini(void)
+{
+	crypto_unregister_alg(&alg);
+}
+
+module_init(twofish_mod_init);
+module_exit(twofish_mod_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION ("Twofish Cipher Algorithm");
+MODULE_ALIAS("twofish");