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+/* serpent.c - Implementation of the Serpent encryption algorithm.
+ * Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser general Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser 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.
+ */
+
+#include <config.h>
+
+#include <string.h>
+#include <stdio.h>
+
+#include "types.h"
+#include "g10lib.h"
+#include "cipher.h"
+#include "bithelp.h"
+
+/* Number of rounds per Serpent encrypt/decrypt operation. */
+#define ROUNDS 32
+
+/* Magic number, used during generating of the subkeys. */
+#define PHI 0x9E3779B9
+
+/* Serpent works on 128 bit blocks. */
+typedef u32 serpent_block_t[4];
+
+/* Serpent key, provided by the user. If the original key is shorter
+ than 256 bits, it is padded. */
+typedef u32 serpent_key_t[8];
+
+/* The key schedule consists of 33 128 bit subkeys. */
+typedef u32 serpent_subkeys_t[ROUNDS + 1][4];
+
+/* A Serpent context. */
+typedef struct serpent_context
+{
+ serpent_subkeys_t keys; /* Generated subkeys. */
+} serpent_context_t;
+
+
+/* A prototype. */
+static const char *serpent_test (void);
+
+
+#define byte_swap_32(x) \
+ (0 \
+ | (((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) \
+ | (((x) & 0x0000ff00) << 8) | (((x) & 0x000000ff) << 24))
+
+/* These are the S-Boxes of Serpent. They are copied from Serpents
+ reference implementation (the optimized one, contained in
+ `floppy2') and are therefore:
+
+ Copyright (C) 1998 Ross Anderson, Eli Biham, Lars Knudsen.
+
+ To quote the Serpent homepage
+ (http://www.cl.cam.ac.uk/~rja14/serpent.html):
+
+ "Serpent is now completely in the public domain, and we impose no
+ restrictions on its use. This was announced on the 21st August at
+ the First AES Candidate Conference. The optimised implementations
+ in the submission package are now under the GNU PUBLIC LICENSE
+ (GPL), although some comments in the code still say otherwise. You
+ are welcome to use Serpent for any application." */
+
+#define SBOX0(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t05, t06, t07, t08, t09; \
+ u32 t11, t12, t13, t14, t15, t17, t01; \
+ t01 = b ^ c ; \
+ t02 = a | d ; \
+ t03 = a ^ b ; \
+ z = t02 ^ t01; \
+ t05 = c | z ; \
+ t06 = a ^ d ; \
+ t07 = b | c ; \
+ t08 = d & t05; \
+ t09 = t03 & t07; \
+ y = t09 ^ t08; \
+ t11 = t09 & y ; \
+ t12 = c ^ d ; \
+ t13 = t07 ^ t11; \
+ t14 = b & t06; \
+ t15 = t06 ^ t13; \
+ w = ~ t15; \
+ t17 = w ^ t14; \
+ x = t12 ^ t17; \
+ }
+
+#define SBOX0_INVERSE(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t06, t08, t09, t10; \
+ u32 t12, t13, t14, t15, t17, t18, t01; \
+ t01 = c ^ d ; \
+ t02 = a | b ; \
+ t03 = b | c ; \
+ t04 = c & t01; \
+ t05 = t02 ^ t01; \
+ t06 = a | t04; \
+ y = ~ t05; \
+ t08 = b ^ d ; \
+ t09 = t03 & t08; \
+ t10 = d | y ; \
+ x = t09 ^ t06; \
+ t12 = a | t05; \
+ t13 = x ^ t12; \
+ t14 = t03 ^ t10; \
+ t15 = a ^ c ; \
+ z = t14 ^ t13; \
+ t17 = t05 & t13; \
+ t18 = t14 | t17; \
+ w = t15 ^ t18; \
+ }
+
+#define SBOX1(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t06, t07, t08; \
+ u32 t10, t11, t12, t13, t16, t17, t01; \
+ t01 = a | d ; \
+ t02 = c ^ d ; \
+ t03 = ~ b ; \
+ t04 = a ^ c ; \
+ t05 = a | t03; \
+ t06 = d & t04; \
+ t07 = t01 & t02; \
+ t08 = b | t06; \
+ y = t02 ^ t05; \
+ t10 = t07 ^ t08; \
+ t11 = t01 ^ t10; \
+ t12 = y ^ t11; \
+ t13 = b & d ; \
+ z = ~ t10; \
+ x = t13 ^ t12; \
+ t16 = t10 | x ; \
+ t17 = t05 & t16; \
+ w = c ^ t17; \
+ }
+
+#define SBOX1_INVERSE(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t06, t07, t08; \
+ u32 t09, t10, t11, t14, t15, t17, t01; \
+ t01 = a ^ b ; \
+ t02 = b | d ; \
+ t03 = a & c ; \
+ t04 = c ^ t02; \
+ t05 = a | t04; \
+ t06 = t01 & t05; \
+ t07 = d | t03; \
+ t08 = b ^ t06; \
+ t09 = t07 ^ t06; \
+ t10 = t04 | t03; \
+ t11 = d & t08; \
+ y = ~ t09; \
+ x = t10 ^ t11; \
+ t14 = a | y ; \
+ t15 = t06 ^ x ; \
+ z = t01 ^ t04; \
+ t17 = c ^ t15; \
+ w = t14 ^ t17; \
+ }
+
+#define SBOX2(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t05, t06, t07, t08; \
+ u32 t09, t10, t12, t13, t14, t01; \
+ t01 = a | c ; \
+ t02 = a ^ b ; \
+ t03 = d ^ t01; \
+ w = t02 ^ t03; \
+ t05 = c ^ w ; \
+ t06 = b ^ t05; \
+ t07 = b | t05; \
+ t08 = t01 & t06; \
+ t09 = t03 ^ t07; \
+ t10 = t02 | t09; \
+ x = t10 ^ t08; \
+ t12 = a | d ; \
+ t13 = t09 ^ x ; \
+ t14 = b ^ t13; \
+ z = ~ t09; \
+ y = t12 ^ t14; \
+ }
+
+#define SBOX2_INVERSE(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t06, t07, t08, t09; \
+ u32 t10, t11, t12, t15, t16, t17, t01; \
+ t01 = a ^ d ; \
+ t02 = c ^ d ; \
+ t03 = a & c ; \
+ t04 = b | t02; \
+ w = t01 ^ t04; \
+ t06 = a | c ; \
+ t07 = d | w ; \
+ t08 = ~ d ; \
+ t09 = b & t06; \
+ t10 = t08 | t03; \
+ t11 = b & t07; \
+ t12 = t06 & t02; \
+ z = t09 ^ t10; \
+ x = t12 ^ t11; \
+ t15 = c & z ; \
+ t16 = w ^ x ; \
+ t17 = t10 ^ t15; \
+ y = t16 ^ t17; \
+ }
+
+#define SBOX3(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t06, t07, t08; \
+ u32 t09, t10, t11, t13, t14, t15, t01; \
+ t01 = a ^ c ; \
+ t02 = a | d ; \
+ t03 = a & d ; \
+ t04 = t01 & t02; \
+ t05 = b | t03; \
+ t06 = a & b ; \
+ t07 = d ^ t04; \
+ t08 = c | t06; \
+ t09 = b ^ t07; \
+ t10 = d & t05; \
+ t11 = t02 ^ t10; \
+ z = t08 ^ t09; \
+ t13 = d | z ; \
+ t14 = a | t07; \
+ t15 = b & t13; \
+ y = t08 ^ t11; \
+ w = t14 ^ t15; \
+ x = t05 ^ t04; \
+ }
+
+#define SBOX3_INVERSE(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t06, t07, t09; \
+ u32 t11, t12, t13, t14, t16, t01; \
+ t01 = c | d ; \
+ t02 = a | d ; \
+ t03 = c ^ t02; \
+ t04 = b ^ t02; \
+ t05 = a ^ d ; \
+ t06 = t04 & t03; \
+ t07 = b & t01; \
+ y = t05 ^ t06; \
+ t09 = a ^ t03; \
+ w = t07 ^ t03; \
+ t11 = w | t05; \
+ t12 = t09 & t11; \
+ t13 = a & y ; \
+ t14 = t01 ^ t05; \
+ x = b ^ t12; \
+ t16 = b | t13; \
+ z = t14 ^ t16; \
+ }
+
+#define SBOX4(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t06, t08, t09; \
+ u32 t10, t11, t12, t13, t14, t15, t16, t01; \
+ t01 = a | b ; \
+ t02 = b | c ; \
+ t03 = a ^ t02; \
+ t04 = b ^ d ; \
+ t05 = d | t03; \
+ t06 = d & t01; \
+ z = t03 ^ t06; \
+ t08 = z & t04; \
+ t09 = t04 & t05; \
+ t10 = c ^ t06; \
+ t11 = b & c ; \
+ t12 = t04 ^ t08; \
+ t13 = t11 | t03; \
+ t14 = t10 ^ t09; \
+ t15 = a & t05; \
+ t16 = t11 | t12; \
+ y = t13 ^ t08; \
+ x = t15 ^ t16; \
+ w = ~ t14; \
+ }
+
+#define SBOX4_INVERSE(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t06, t07, t09; \
+ u32 t10, t11, t12, t13, t15, t01; \
+ t01 = b | d ; \
+ t02 = c | d ; \
+ t03 = a & t01; \
+ t04 = b ^ t02; \
+ t05 = c ^ d ; \
+ t06 = ~ t03; \
+ t07 = a & t04; \
+ x = t05 ^ t07; \
+ t09 = x | t06; \
+ t10 = a ^ t07; \
+ t11 = t01 ^ t09; \
+ t12 = d ^ t04; \
+ t13 = c | t10; \
+ z = t03 ^ t12; \
+ t15 = a ^ t04; \
+ y = t11 ^ t13; \
+ w = t15 ^ t09; \
+ }
+
+#define SBOX5(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t07, t08, t09; \
+ u32 t10, t11, t12, t13, t14, t01; \
+ t01 = b ^ d ; \
+ t02 = b | d ; \
+ t03 = a & t01; \
+ t04 = c ^ t02; \
+ t05 = t03 ^ t04; \
+ w = ~ t05; \
+ t07 = a ^ t01; \
+ t08 = d | w ; \
+ t09 = b | t05; \
+ t10 = d ^ t08; \
+ t11 = b | t07; \
+ t12 = t03 | w ; \
+ t13 = t07 | t10; \
+ t14 = t01 ^ t11; \
+ y = t09 ^ t13; \
+ x = t07 ^ t08; \
+ z = t12 ^ t14; \
+ }
+
+#define SBOX5_INVERSE(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t07, t08, t09; \
+ u32 t10, t12, t13, t15, t16, t01; \
+ t01 = a & d ; \
+ t02 = c ^ t01; \
+ t03 = a ^ d ; \
+ t04 = b & t02; \
+ t05 = a & c ; \
+ w = t03 ^ t04; \
+ t07 = a & w ; \
+ t08 = t01 ^ w ; \
+ t09 = b | t05; \
+ t10 = ~ b ; \
+ x = t08 ^ t09; \
+ t12 = t10 | t07; \
+ t13 = w | x ; \
+ z = t02 ^ t12; \
+ t15 = t02 ^ t13; \
+ t16 = b ^ d ; \
+ y = t16 ^ t15; \
+ }
+
+#define SBOX6(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t07, t08, t09, t10; \
+ u32 t11, t12, t13, t15, t17, t18, t01; \
+ t01 = a & d ; \
+ t02 = b ^ c ; \
+ t03 = a ^ d ; \
+ t04 = t01 ^ t02; \
+ t05 = b | c ; \
+ x = ~ t04; \
+ t07 = t03 & t05; \
+ t08 = b & x ; \
+ t09 = a | c ; \
+ t10 = t07 ^ t08; \
+ t11 = b | d ; \
+ t12 = c ^ t11; \
+ t13 = t09 ^ t10; \
+ y = ~ t13; \
+ t15 = x & t03; \
+ z = t12 ^ t07; \
+ t17 = a ^ b ; \
+ t18 = y ^ t15; \
+ w = t17 ^ t18; \
+ }
+
+#define SBOX6_INVERSE(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t06, t07, t08, t09; \
+ u32 t12, t13, t14, t15, t16, t17, t01; \
+ t01 = a ^ c ; \
+ t02 = ~ c ; \
+ t03 = b & t01; \
+ t04 = b | t02; \
+ t05 = d | t03; \
+ t06 = b ^ d ; \
+ t07 = a & t04; \
+ t08 = a | t02; \
+ t09 = t07 ^ t05; \
+ x = t06 ^ t08; \
+ w = ~ t09; \
+ t12 = b & w ; \
+ t13 = t01 & t05; \
+ t14 = t01 ^ t12; \
+ t15 = t07 ^ t13; \
+ t16 = d | t02; \
+ t17 = a ^ x ; \
+ z = t17 ^ t15; \
+ y = t16 ^ t14; \
+ }
+
+#define SBOX7(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t05, t06, t08, t09, t10; \
+ u32 t11, t13, t14, t15, t16, t17, t01; \
+ t01 = a & c ; \
+ t02 = ~ d ; \
+ t03 = a & t02; \
+ t04 = b | t01; \
+ t05 = a & b ; \
+ t06 = c ^ t04; \
+ z = t03 ^ t06; \
+ t08 = c | z ; \
+ t09 = d | t05; \
+ t10 = a ^ t08; \
+ t11 = t04 & z ; \
+ x = t09 ^ t10; \
+ t13 = b ^ x ; \
+ t14 = t01 ^ x ; \
+ t15 = c ^ t05; \
+ t16 = t11 | t13; \
+ t17 = t02 | t14; \
+ w = t15 ^ t17; \
+ y = a ^ t16; \
+ }
+
+#define SBOX7_INVERSE(a, b, c, d, w, x, y, z) \
+ { \
+ u32 t02, t03, t04, t06, t07, t08, t09; \
+ u32 t10, t11, t13, t14, t15, t16, t01; \
+ t01 = a & b ; \
+ t02 = a | b ; \
+ t03 = c | t01; \
+ t04 = d & t02; \
+ z = t03 ^ t04; \
+ t06 = b ^ t04; \
+ t07 = d ^ z ; \
+ t08 = ~ t07; \
+ t09 = t06 | t08; \
+ t10 = b ^ d ; \
+ t11 = a | d ; \
+ x = a ^ t09; \
+ t13 = c ^ t06; \
+ t14 = c & t11; \
+ t15 = d | x ; \
+ t16 = t01 | t10; \
+ w = t13 ^ t15; \
+ y = t14 ^ t16; \
+ }
+
+/* XOR BLOCK1 into BLOCK0. */
+#define BLOCK_XOR(block0, block1) \
+ { \
+ block0[0] ^= block1[0]; \
+ block0[1] ^= block1[1]; \
+ block0[2] ^= block1[2]; \
+ block0[3] ^= block1[3]; \
+ }
+
+/* Copy BLOCK_SRC to BLOCK_DST. */
+#define BLOCK_COPY(block_dst, block_src) \
+ { \
+ block_dst[0] = block_src[0]; \
+ block_dst[1] = block_src[1]; \
+ block_dst[2] = block_src[2]; \
+ block_dst[3] = block_src[3]; \
+ }
+
+/* Apply SBOX number WHICH to to the block found in ARRAY0 at index
+ INDEX, writing the output to the block found in ARRAY1 at index
+ INDEX. */
+#define SBOX(which, array0, array1, index) \
+ SBOX##which (array0[index + 0], array0[index + 1], \
+ array0[index + 2], array0[index + 3], \
+ array1[index + 0], array1[index + 1], \
+ array1[index + 2], array1[index + 3]);
+
+/* Apply inverse SBOX number WHICH to to the block found in ARRAY0 at
+ index INDEX, writing the output to the block found in ARRAY1 at
+ index INDEX. */
+#define SBOX_INVERSE(which, array0, array1, index) \
+ SBOX##which##_INVERSE (array0[index + 0], array0[index + 1], \
+ array0[index + 2], array0[index + 3], \
+ array1[index + 0], array1[index + 1], \
+ array1[index + 2], array1[index + 3]);
+
+/* Apply the linear transformation to BLOCK. */
+#define LINEAR_TRANSFORMATION(block) \
+ { \
+ block[0] = rol (block[0], 13); \
+ block[2] = rol (block[2], 3); \
+ block[1] = block[1] ^ block[0] ^ block[2]; \
+ block[3] = block[3] ^ block[2] ^ (block[0] << 3); \
+ block[1] = rol (block[1], 1); \
+ block[3] = rol (block[3], 7); \
+ block[0] = block[0] ^ block[1] ^ block[3]; \
+ block[2] = block[2] ^ block[3] ^ (block[1] << 7); \
+ block[0] = rol (block[0], 5); \
+ block[2] = rol (block[2], 22); \
+ }
+
+/* Apply the inverse linear transformation to BLOCK. */
+#define LINEAR_TRANSFORMATION_INVERSE(block) \
+ { \
+ block[2] = ror (block[2], 22); \
+ block[0] = ror (block[0] , 5); \
+ block[2] = block[2] ^ block[3] ^ (block[1] << 7); \
+ block[0] = block[0] ^ block[1] ^ block[3]; \
+ block[3] = ror (block[3], 7); \
+ block[1] = ror (block[1], 1); \
+ block[3] = block[3] ^ block[2] ^ (block[0] << 3); \
+ block[1] = block[1] ^ block[0] ^ block[2]; \
+ block[2] = ror (block[2], 3); \
+ block[0] = ror (block[0], 13); \
+ }
+
+/* Apply a Serpent round to BLOCK, using the SBOX number WHICH and the
+ subkeys contained in SUBKEYS. Use BLOCK_TMP as temporary storage.
+ This macro increments `round'. */
+#define ROUND(which, subkeys, block, block_tmp) \
+ { \
+ BLOCK_XOR (block, subkeys[round]); \
+ round++; \
+ SBOX (which, block, block_tmp, 0); \
+ LINEAR_TRANSFORMATION (block_tmp); \
+ BLOCK_COPY (block, block_tmp); \
+ }
+
+/* Apply the last Serpent round to BLOCK, using the SBOX number WHICH
+ and the subkeys contained in SUBKEYS. Use BLOCK_TMP as temporary
+ storage. The result will be stored in BLOCK_TMP. This macro
+ increments `round'. */
+#define ROUND_LAST(which, subkeys, block, block_tmp) \
+ { \
+ BLOCK_XOR (block, subkeys[round]); \
+ round++; \
+ SBOX (which, block, block_tmp, 0); \
+ BLOCK_XOR (block_tmp, subkeys[round]); \
+ round++; \
+ }
+
+/* Apply an inverse Serpent round to BLOCK, using the SBOX number
+ WHICH and the subkeys contained in SUBKEYS. Use BLOCK_TMP as
+ temporary storage. This macro increments `round'. */
+#define ROUND_INVERSE(which, subkey, block, block_tmp) \
+ { \
+ LINEAR_TRANSFORMATION_INVERSE (block); \
+ SBOX_INVERSE (which, block, block_tmp, 0); \
+ BLOCK_XOR (block_tmp, subkey[round]); \
+ round--; \
+ BLOCK_COPY (block, block_tmp); \
+ }
+
+/* Apply the first Serpent round to BLOCK, using the SBOX number WHICH
+ and the subkeys contained in SUBKEYS. Use BLOCK_TMP as temporary
+ storage. The result will be stored in BLOCK_TMP. This macro
+ increments `round'. */
+#define ROUND_FIRST_INVERSE(which, subkeys, block, block_tmp) \
+ { \
+ BLOCK_XOR (block, subkeys[round]); \
+ round--; \
+ SBOX_INVERSE (which, block, block_tmp, 0); \
+ BLOCK_XOR (block_tmp, subkeys[round]); \
+ round--; \
+ }
+
+/* Convert the user provided key KEY of KEY_LENGTH bytes into the
+ internally used format. */
+static void
+serpent_key_prepare (const byte *key, unsigned int key_length,
+ serpent_key_t key_prepared)
+{
+ int i;
+
+ /* Copy key. */
+ memcpy (key_prepared, key, key_length);
+ key_length /= 4;
+#ifdef WORDS_BIGENDIAN
+ for (i = 0; i < key_length; i++)
+ key_prepared[i] = byte_swap_32 (key_prepared[i]);
+#else
+ i = key_length;
+#endif
+ if (i < 8)
+ {
+ /* Key must be padded according to the Serpent
+ specification. */
+ key_prepared[i] = 0x00000001;
+
+ for (i++; i < 8; i++)
+ key_prepared[i] = 0;
+ }
+}
+
+/* Derive the 33 subkeys from KEY and store them in SUBKEYS. */
+static void
+serpent_subkeys_generate (serpent_key_t key, serpent_subkeys_t subkeys)
+{
+ u32 w_real[140]; /* The `prekey'. */
+ u32 k[132];
+ u32 *w = &w_real[8];
+ int i, j;
+
+ /* Initialize with key values. */
+ for (i = 0; i < 8; i++)
+ w[i - 8] = key[i];
+
+ /* Expand to intermediate key using the affine recurrence. */
+ for (i = 0; i < 132; i++)
+ w[i] = rol (w[i - 8] ^ w[i - 5] ^ w[i - 3] ^ w[i - 1] ^ PHI ^ i, 11);
+
+ /* Calculate subkeys via S-Boxes, in bitslice mode. */
+ SBOX (3, w, k, 0);
+ SBOX (2, w, k, 4);
+ SBOX (1, w, k, 8);
+ SBOX (0, w, k, 12);
+ SBOX (7, w, k, 16);
+ SBOX (6, w, k, 20);
+ SBOX (5, w, k, 24);
+ SBOX (4, w, k, 28);
+ SBOX (3, w, k, 32);
+ SBOX (2, w, k, 36);
+ SBOX (1, w, k, 40);
+ SBOX (0, w, k, 44);
+ SBOX (7, w, k, 48);
+ SBOX (6, w, k, 52);
+ SBOX (5, w, k, 56);
+ SBOX (4, w, k, 60);
+ SBOX (3, w, k, 64);
+ SBOX (2, w, k, 68);
+ SBOX (1, w, k, 72);
+ SBOX (0, w, k, 76);
+ SBOX (7, w, k, 80);
+ SBOX (6, w, k, 84);
+ SBOX (5, w, k, 88);
+ SBOX (4, w, k, 92);
+ SBOX (3, w, k, 96);
+ SBOX (2, w, k, 100);
+ SBOX (1, w, k, 104);
+ SBOX (0, w, k, 108);
+ SBOX (7, w, k, 112);
+ SBOX (6, w, k, 116);
+ SBOX (5, w, k, 120);
+ SBOX (4, w, k, 124);
+ SBOX (3, w, k, 128);
+
+ /* Renumber subkeys. */
+ for (i = 0; i < ROUNDS + 1; i++)
+ for (j = 0; j < 4; j++)
+ subkeys[i][j] = k[4 * i + j];
+}
+
+/* Initialize CONTEXT with the key KEY of KEY_LENGTH bits. */
+static void
+serpent_setkey_internal (serpent_context_t *context,
+ const byte *key, unsigned int key_length)
+{
+ serpent_key_t key_prepared;
+
+ serpent_key_prepare (key, key_length, key_prepared);
+ serpent_subkeys_generate (key_prepared, context->keys);
+ _gcry_burn_stack (272 * sizeof (u32));
+}
+
+/* Initialize CTX with the key KEY of KEY_LENGTH bytes. */
+static gcry_err_code_t
+serpent_setkey (void *ctx,
+ const byte *key, unsigned int key_length)
+{
+ serpent_context_t *context = ctx;
+ static const char *serpent_test_ret;
+ static int serpent_init_done;
+ gcry_err_code_t ret = GPG_ERR_NO_ERROR;
+
+ if (! serpent_init_done)
+ {
+ /* Execute a self-test the first time, Serpent is used. */
+ serpent_test_ret = serpent_test ();
+ if (serpent_test_ret)
+ log_error ("Serpent test failure: %s\n", serpent_test_ret);
+ serpent_init_done = 1;
+ }
+
+ if (serpent_test_ret)
+ ret = GPG_ERR_SELFTEST_FAILED;
+ else
+ {
+ serpent_setkey_internal (context, key, key_length);
+ _gcry_burn_stack (sizeof (serpent_key_t));
+ }
+
+ return ret;
+}
+
+static void
+serpent_encrypt_internal (serpent_context_t *context,
+ const byte *input, byte *output)
+{
+ serpent_block_t b, b_next;
+ int round = 0;
+
+ memcpy (b, input, sizeof (b));
+#ifdef WORDS_BIGENDIAN
+ b[0] = byte_swap_32 (b[0]);
+ b[1] = byte_swap_32 (b[1]);
+ b[2] = byte_swap_32 (b[2]);
+ b[3] = byte_swap_32 (b[3]);
+#endif
+
+ ROUND (0, context->keys, b, b_next);
+ ROUND (1, context->keys, b, b_next);
+ ROUND (2, context->keys, b, b_next);
+ ROUND (3, context->keys, b, b_next);
+ ROUND (4, context->keys, b, b_next);
+ ROUND (5, context->keys, b, b_next);
+ ROUND (6, context->keys, b, b_next);
+ ROUND (7, context->keys, b, b_next);
+ ROUND (0, context->keys, b, b_next);
+ ROUND (1, context->keys, b, b_next);
+ ROUND (2, context->keys, b, b_next);
+ ROUND (3, context->keys, b, b_next);
+ ROUND (4, context->keys, b, b_next);
+ ROUND (5, context->keys, b, b_next);
+ ROUND (6, context->keys, b, b_next);
+ ROUND (7, context->keys, b, b_next);
+ ROUND (0, context->keys, b, b_next);
+ ROUND (1, context->keys, b, b_next);
+ ROUND (2, context->keys, b, b_next);
+ ROUND (3, context->keys, b, b_next);
+ ROUND (4, context->keys, b, b_next);
+ ROUND (5, context->keys, b, b_next);
+ ROUND (6, context->keys, b, b_next);
+ ROUND (7, context->keys, b, b_next);
+ ROUND (0, context->keys, b, b_next);
+ ROUND (1, context->keys, b, b_next);
+ ROUND (2, context->keys, b, b_next);
+ ROUND (3, context->keys, b, b_next);
+ ROUND (4, context->keys, b, b_next);
+ ROUND (5, context->keys, b, b_next);
+ ROUND (6, context->keys, b, b_next);
+
+ ROUND_LAST (7, context->keys, b, b_next);
+
+#ifdef WORDS_BIGENDIAN
+ b_next[0] = byte_swap_32 (b_next[0]);
+ b_next[1] = byte_swap_32 (b_next[1]);
+ b_next[2] = byte_swap_32 (b_next[2]);
+ b_next[3] = byte_swap_32 (b_next[3]);
+#endif
+ memcpy (output, b_next, sizeof (b_next));
+}
+
+static void
+serpent_decrypt_internal (serpent_context_t *context,
+ const byte *input, byte *output)
+{
+ serpent_block_t b, b_next;
+ int round = ROUNDS;
+
+ memcpy (b_next, input, sizeof (b));
+#ifdef WORDS_BIGENDIAN
+ b_next[0] = byte_swap_32 (b_next[0]);
+ b_next[1] = byte_swap_32 (b_next[1]);
+ b_next[2] = byte_swap_32 (b_next[2]);
+ b_next[3] = byte_swap_32 (b_next[3]);
+#endif
+
+ ROUND_FIRST_INVERSE (7, context->keys, b_next, b);
+
+ ROUND_INVERSE (6, context->keys, b, b_next);
+ ROUND_INVERSE (5, context->keys, b, b_next);
+ ROUND_INVERSE (4, context->keys, b, b_next);
+ ROUND_INVERSE (3, context->keys, b, b_next);
+ ROUND_INVERSE (2, context->keys, b, b_next);
+ ROUND_INVERSE (1, context->keys, b, b_next);
+ ROUND_INVERSE (0, context->keys, b, b_next);
+ ROUND_INVERSE (7, context->keys, b, b_next);
+ ROUND_INVERSE (6, context->keys, b, b_next);
+ ROUND_INVERSE (5, context->keys, b, b_next);
+ ROUND_INVERSE (4, context->keys, b, b_next);
+ ROUND_INVERSE (3, context->keys, b, b_next);
+ ROUND_INVERSE (2, context->keys, b, b_next);
+ ROUND_INVERSE (1, context->keys, b, b_next);
+ ROUND_INVERSE (0, context->keys, b, b_next);
+ ROUND_INVERSE (7, context->keys, b, b_next);
+ ROUND_INVERSE (6, context->keys, b, b_next);
+ ROUND_INVERSE (5, context->keys, b, b_next);
+ ROUND_INVERSE (4, context->keys, b, b_next);
+ ROUND_INVERSE (3, context->keys, b, b_next);
+ ROUND_INVERSE (2, context->keys, b, b_next);
+ ROUND_INVERSE (1, context->keys, b, b_next);
+ ROUND_INVERSE (0, context->keys, b, b_next);
+ ROUND_INVERSE (7, context->keys, b, b_next);
+ ROUND_INVERSE (6, context->keys, b, b_next);
+ ROUND_INVERSE (5, context->keys, b, b_next);
+ ROUND_INVERSE (4, context->keys, b, b_next);
+ ROUND_INVERSE (3, context->keys, b, b_next);
+ ROUND_INVERSE (2, context->keys, b, b_next);
+ ROUND_INVERSE (1, context->keys, b, b_next);
+ ROUND_INVERSE (0, context->keys, b, b_next);
+
+#ifdef WORDS_BIGENDIAN
+ b_next[0] = byte_swap_32 (b_next[0]);
+ b_next[1] = byte_swap_32 (b_next[1]);
+ b_next[2] = byte_swap_32 (b_next[2]);
+ b_next[3] = byte_swap_32 (b_next[3]);
+#endif
+ memcpy (output, b_next, sizeof (b_next));
+}
+
+static void
+serpent_encrypt (void *ctx, byte *buffer_out, const byte *buffer_in)
+{
+ serpent_context_t *context = ctx;
+
+ serpent_encrypt_internal (context, buffer_in, buffer_out);
+ _gcry_burn_stack (2 * sizeof (serpent_block_t));
+}
+
+static void
+serpent_decrypt (void *ctx, byte *buffer_out, const byte *buffer_in)
+{
+ serpent_context_t *context = ctx;
+
+ serpent_decrypt_internal (context, buffer_in, buffer_out);
+ _gcry_burn_stack (2 * sizeof (serpent_block_t));
+}
+
+
+
+/* Serpent test. */
+
+static const char *
+serpent_test (void)
+{
+ serpent_context_t context;
+ unsigned char scratch[16];
+ unsigned int i;
+
+ static struct test
+ {
+ int key_length;
+ unsigned char key[32];
+ unsigned char text_plain[16];
+ unsigned char text_cipher[16];
+ } test_data[] =
+ {
+ {
+ 16,
+ "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
+ "\xD2\x9D\x57\x6F\xCE\xA3\xA3\xA7\xED\x90\x99\xF2\x92\x73\xD7\x8E",
+ "\xB2\x28\x8B\x96\x8A\xE8\xB0\x86\x48\xD1\xCE\x96\x06\xFD\x99\x2D"
+ },
+ {
+ 24,
+ "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+ "\x00\x00\x00\x00\x00\x00\x00\x00",
+ "\xD2\x9D\x57\x6F\xCE\xAB\xA3\xA7\xED\x98\x99\xF2\x92\x7B\xD7\x8E",
+ "\x13\x0E\x35\x3E\x10\x37\xC2\x24\x05\xE8\xFA\xEF\xB2\xC3\xC3\xE9"
+ },
+ {
+ 32,
+ "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+ "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
+ "\xD0\x95\x57\x6F\xCE\xA3\xE3\xA7\xED\x98\xD9\xF2\x90\x73\xD7\x8E",
+ "\xB9\x0E\xE5\x86\x2D\xE6\x91\x68\xF2\xBD\xD5\x12\x5B\x45\x47\x2B"
+ },
+ {
+ 32,
+ "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+ "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
+ "\x00\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x03\x00\x00\x00",
+ "\x20\x61\xA4\x27\x82\xBD\x52\xEC\x69\x1E\xC3\x83\xB0\x3B\xA7\x7C"
+ },
+ {
+ 0
+ },
+ };
+
+ for (i = 0; test_data[i].key_length; i++)
+ {
+ serpent_setkey_internal (&context, test_data[i].key,
+ test_data[i].key_length);
+ serpent_encrypt_internal (&context, test_data[i].text_plain, scratch);
+
+ if (memcmp (scratch, test_data[i].text_cipher, sizeof (serpent_block_t)))
+ switch (test_data[i].key_length)
+ {
+ case 16:
+ return "Serpent-128 test encryption failed.";
+ case 24:
+ return "Serpent-192 test encryption failed.";
+ case 32:
+ return "Serpent-256 test encryption failed.";
+ }
+
+ serpent_decrypt_internal (&context, test_data[i].text_cipher, scratch);
+ if (memcmp (scratch, test_data[i].text_plain, sizeof (serpent_block_t)))
+ switch (test_data[i].key_length)
+ {
+ case 16:
+ return "Serpent-128 test decryption failed.";
+ case 24:
+ return "Serpent-192 test decryption failed.";
+ case 32:
+ return "Serpent-256 test decryption failed.";
+ }
+ }
+
+ return NULL;
+}
+
+
+
+/* "SERPENT" is an alias for "SERPENT128". */
+static const char *cipher_spec_serpent128_aliases[] =
+ {
+ "SERPENT",
+ NULL
+ };
+
+gcry_cipher_spec_t _gcry_cipher_spec_serpent128 =
+ {
+ "SERPENT128", cipher_spec_serpent128_aliases, NULL, 16, 128,
+ sizeof (serpent_context_t),
+ serpent_setkey, serpent_encrypt, serpent_decrypt
+ };
+
+gcry_cipher_spec_t _gcry_cipher_spec_serpent192 =
+ {
+ "SERPENT192", NULL, NULL, 16, 192,
+ sizeof (serpent_context_t),
+ serpent_setkey, serpent_encrypt, serpent_decrypt
+ };
+
+gcry_cipher_spec_t _gcry_cipher_spec_serpent256 =
+ {
+ "SERPENT256", NULL, NULL, 16, 256,
+ sizeof (serpent_context_t),
+ serpent_setkey, serpent_encrypt, serpent_decrypt
+ };