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/* serpent-encrypt.c
*
* The serpent block cipher.
*
* For more details on this algorithm, see the Serpent website at
* http://www.cl.cam.ac.uk/~rja14/serpent.html
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2011 Niels Möller
* Copyright (C) 2010, 2011 Simon Josefsson
* Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
*
* The nettle library 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.
*
* The nettle library 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 the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
/* This file is derived from cipher/serpent.c in Libgcrypt v1.4.6.
The adaption to Nettle was made by Simon Josefsson on 2010-12-07
with final touches on 2011-05-30. Changes include replacing
libgcrypt with nettle in the license template, renaming
serpent_context to serpent_ctx, renaming u32 to uint32_t, removing
libgcrypt stubs and selftests, modifying entry function prototypes,
using FOR_BLOCKS to iterate through data in encrypt/decrypt, using
LE_READ_UINT32 and LE_WRITE_UINT32 to access data in
encrypt/decrypt, and running indent on the code. */
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <assert.h>
#include <limits.h>
#include "serpent.h"
#include "macros.h"
#include "serpent-internal.h"
/* 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." */
/* S0: 3 8 15 1 10 6 5 11 14 13 4 2 7 0 9 12 */
/* Could easily let y0, y1 overlap with x0, x1, and possibly also x2 and y2 */
#define SBOX0(x0, x1, x2, x3, y0, y1, y2, y3) \
do { \
y3 = x1 ^ x2; \
y0 = x0 | x3; \
y1 = x0 ^ x1; \
y3 ^= y0; \
y2 = x2 | y3; \
x0 ^= x3; \
y2 &= x3; \
x3 ^= x2; \
x2 |= x1; \
y0 = y1 & x2; \
y2 ^= y0; \
y0 &= y2; \
y0 ^= x2; \
x1 &= x0; \
y0 ^= x0; \
y0 = ~ y0; \
y1 = y0 ^ x1; \
y1 ^= x3; \
} while (0)
/* FIXME: Arrange for some overlap between inputs and outputs? */
/* S1: 15 12 2 7 9 0 5 10 1 11 14 8 6 13 3 4 */
/* Original single-assignment form:
t01 = x0 | x3;
t02 = x2 ^ x3;
t03 = ~ x1;
t04 = x0 ^ x2;
t05 = x0 | t03;
t06 = x3 & t04;
t07 = t01 & t02;
t08 = x1 | t06;
y2 = t02 ^ t05;
t10 = t07 ^ t08;
t11 = t01 ^ t10;
t12 = y2 ^ t11;
t13 = x1 & x3;
y3 = ~ t10;
y1 = t13 ^ t12;
t16 = t10 | y1;
t17 = t05 & t16;
y0 = x2 ^ t17;
*/
#define SBOX1(x0, x1, x2, x3, y0, y1, y2, y3) \
do { \
y1 = x0 | x3; \
y2 = x2 ^ x3; \
y0 = ~ x1; \
y3 = x0 ^ x2; \
y0 |= x0; \
y3 &= x3; \
x0 = y1 & y2; \
y3 |= x1; \
y2 ^= y0; \
y3 ^= x0; \
x0 = y1 ^ y3; \
x0 ^= y2; \
y1 = x1 & x3; \
y1 ^= x0; \
x3 = y1 | y3; \
y3 = ~ y3; \
y0 &= x3; \
y0 ^= x2; \
} while (0)
/* FIXME: Arrange for some overlap between inputs and outputs? */
/* S2: 8 6 7 9 3 12 10 15 13 1 14 4 0 11 5 2 */
#define SBOX2(x0, x1, x2, x3, y0, y1, y2, y3) \
do { \
y2 = x0 | x2; \
y1 = x0 ^ x1; \
y3 = x3 ^ y2; \
y0 = y1 ^ y3; \
x3 |= x0; \
x2 ^= y0; \
x0 = x1 ^ x2; \
x2 |= x1; \
x0 &= y2; \
y3 ^= x2; \
y1 |= y3; \
y1 ^= x0; \
y2 = y3 ^ y1; \
y2 ^= x1; \
y3 = ~ y3; \
y2 ^= x3; \
} while (0)
/* S3: 0 15 11 8 12 9 6 3 13 1 2 4 10 7 5 14 */
/* Original single-assignment form:
t01 = x0 ^ x2;
t02 = x0 | x3;
t03 = x0 & x3;
t04 = t01 & t02;
t05 = x1 | t03;
t06 = x0 & x1;
t07 = x3 ^ t04;
t08 = x2 | t06;
t09 = x1 ^ t07;
t10 = x3 & t05;
t11 = t02 ^ t10;
y3 = t08 ^ t09;
t13 = x3 | y3;
t14 = x0 | t07;
t15 = x1 & t13;
y2 = t08 ^ t11;
y0 = t14 ^ t15;
y1 = t05 ^ t04;
*/
#define SBOX3(x0, x1, x2, x3, y0, y1, y2, y3) \
do { \
y1 = x0 ^ x2; \
y0 = x0 | x3; \
y3 = x0 & x3; \
y1 &= y0; \
y3 |= x1; \
y2 = x0 & x1; \
y2 |= x2; \
x2 = x3 ^ y1; \
y1 ^= y3; \
x0 |= x2; \
x2 ^= x1; \
y3 &= x3; \
y0 ^= y3; \
y3 = y2 ^ x2; \
y2 ^= y0; \
x3 |= y3; \
x1 &= x3; \
y0 = x0 ^ x1; \
} while (0)
/* S4: 1 15 8 3 12 0 11 6 2 5 4 10 9 14 7 13 */
/* Original single-assignment form:
t01 = x0 | x1;
t02 = x1 | x2;
t03 = x0 ^ t02;
t04 = x1 ^ x3;
t05 = x3 | t03;
t06 = x3 & t01;
y3 = t03 ^ t06;
t08 = y3 & t04;
t09 = t04 & t05;
t10 = x2 ^ t06;
t11 = x1 & x2;
t12 = t04 ^ t08;
t13 = t11 | t03;
t14 = t10 ^ t09;
t15 = x0 & t05;
t16 = t11 | t12;
y2 = t13 ^ t08;
y1 = t15 ^ t16;
y0 = ~ t14;
*/
#define SBOX4(x0, x1, x2, x3, y0, y1, y2, y3) \
do { \
y3 = x0 | x1; \
y2 = x1 | x2; \
y2 ^= x0; \
y3 &= x3; \
y0 = x1 ^ x3; \
x3 |= y2; \
x0 &= x3; \
x1 &= x2; \
x2 ^= y3; \
y3 ^= y2; \
y2 |= x1; \
y1 = y3 & y0; \
y2 ^= y1; \
y1 ^= y0; \
y1 |= x1; \
y1 ^= x0; \
y0 &= x3; \
y0 ^= x2; \
y0 = ~y0; \
} while (0)
/* S5: 15 5 2 11 4 10 9 12 0 3 14 8 13 6 7 1 */
/* Original single-assignment form:
t01 = x1 ^ x3;
t02 = x1 | x3;
t03 = x0 & t01;
t04 = x2 ^ t02;
t05 = t03 ^ t04;
y0 = ~ t05;
t07 = x0 ^ t01;
t08 = x3 | y0;
t09 = x1 | t05;
t10 = x3 ^ t08;
t11 = x1 | t07;
t12 = t03 | y0;
t13 = t07 | t10;
t14 = t01 ^ t11;
y2 = t09 ^ t13;
y1 = t07 ^ t08;
y3 = t12 ^ t14;
*/
#define SBOX5(x0, x1, x2, x3, y0, y1, y2, y3) \
do { \
y0 = x1 | x3; \
y0 ^= x2; \
x2 = x1 ^ x3; \
y2 = x0 ^ x2; \
x0 &= x2; \
y0 ^= x0; \
y3 = x1 | y2; \
x1 |= y0; \
y0 = ~y0; \
x0 |= y0; \
y3 ^= x2; \
y3 ^= x0; \
y1 = x3 | y0; \
x3 ^= y1; \
y1 ^= y2; \
y2 |= x3; \
y2 ^= x1; \
} while (0)
/* S6: 7 2 12 5 8 4 6 11 14 9 1 15 13 3 10 0 */
/* Original single-assignment form:
t01 = x0 & x3;
t02 = x1 ^ x2;
t03 = x0 ^ x3;
t04 = t01 ^ t02;
t05 = x1 | x2;
y1 = ~ t04;
t07 = t03 & t05;
t08 = x1 & y1;
t09 = x0 | x2;
t10 = t07 ^ t08;
t11 = x1 | x3;
t12 = x2 ^ t11;
t13 = t09 ^ t10;
y2 = ~ t13;
t15 = y1 & t03;
y3 = t12 ^ t07;
t17 = x0 ^ x1;
t18 = y2 ^ t15;
y0 = t17 ^ t18;
*/
#define SBOX6(x0, x1, x2, x3, y0, y1, y2, y3) \
do { \
y0 = x0 ^ x3; \
y1 = x0 & x3; \
y2 = x0 | x2; \
x3 |= x1; \
x3 ^= x2; \
x0 ^= x1; \
y3 = x1 | x2; \
x2 ^= x1; \
y3 &= y0; \
y1 ^= x2; \
y1 = ~y1; \
y0 &= y1; \
x1 &= y1; \
x1 ^= y3; \
y3 ^= x3; \
y2 ^= x1; \
y2 = ~y2; \
y0 ^= y2; \
y0 ^= x0; \
} while (0)
/* S7: 1 13 15 0 14 8 2 11 7 4 12 10 9 3 5 6 */
/* Original single-assignment form:
t01 = x0 & x2;
t02 = ~ x3;
t03 = x0 & t02;
t04 = x1 | t01;
t05 = x0 & x1;
t06 = x2 ^ t04;
y3 = t03 ^ t06;
t08 = x2 | y3;
t09 = x3 | t05;
t10 = x0 ^ t08;
t11 = t04 & y3;
y1 = t09 ^ t10;
t13 = x1 ^ y1;
t14 = t01 ^ y1;
t15 = x2 ^ t05;
t16 = t11 | t13;
t17 = t02 | t14;
y0 = t15 ^ t17;
y2 = x0 ^ t16;
*/
/* It appears impossible to do this with only 8 registers. We
recompute t02, and t04 (if we have spare registers, hopefully the
compiler can recognize them as common subexpressions). */
#define SBOX7(x0, x1, x2, x3, y0, y1, y2, y3) \
do { \
y0 = x0 & x2; \
y3 = x1 | y0; /* t04 */ \
y3 ^= x2; \
y1 = ~x3; /* t02 */ \
y1 &= x0; \
y3 ^= y1; \
y1 = x2 | y3; \
y1 ^= x0; \
y2 = x0 & x1; \
x2 ^= y2; \
y2 |= x3; \
y1 ^= y2; \
y2 = x1 | y0; /* t04 */ \
y2 &= y3; \
x1 ^= y1; \
y2 |= x1; \
y2 ^= x0; \
y0 ^= y1; \
x3 = ~x3; /* t02 */ \
y0 |= x3; \
y0 ^= x2; \
} while (0)
/* In-place linear transformation. */
#define LINEAR_TRANSFORMATION(x0,x1,x2,x3) \
do { \
x0 = ROL32 (x0, 13); \
x2 = ROL32 (x2, 3); \
x1 = x1 ^ x0 ^ x2; \
x3 = x3 ^ x2 ^ (x0 << 3); \
x1 = ROL32 (x1, 1); \
x3 = ROL32 (x3, 7); \
x0 = x0 ^ x1 ^ x3; \
x2 = x2 ^ x3 ^ (x1 << 7); \
x0 = ROL32 (x0, 5); \
x2 = ROL32 (x2, 22); \
} while (0)
/* Round inputs are x0,x1,x2,x3 (destroyed), and round outputs are
y0,y1,y2,y3. */
#define ROUND(which, subkey, x0,x1,x2,x3, y0,y1,y2,y3) \
do { \
KEYXOR(x0,x1,x2,x3, subkey); \
SBOX##which(x0,x1,x2,x3, y0,y1,y2,y3); \
LINEAR_TRANSFORMATION(y0,y1,y2,y3); \
} while (0)
#if HAVE_NATIVE_64_BIT
#define LINEAR_TRANSFORMATION64(x0,x1,x2,x3) \
do { \
x0 = ROL64 (x0, 13); \
x2 = ROL64 (x2, 3); \
x1 = x1 ^ x0 ^ x2; \
x3 = x3 ^ x2 ^ RSHIFT64(x0, 3); \
x1 = ROL64 (x1, 1); \
x3 = ROL64 (x3, 7); \
x0 = x0 ^ x1 ^ x3; \
x2 = x2 ^ x3 ^ RSHIFT64(x1, 7); \
x0 = ROL64 (x0, 5); \
x2 = ROL64 (x2, 22); \
} while (0)
#define ROUND64(which, subkey, x0,x1,x2,x3, y0,y1,y2,y3) \
do { \
KEYXOR64(x0,x1,x2,x3, subkey); \
SBOX##which(x0,x1,x2,x3, y0,y1,y2,y3); \
LINEAR_TRANSFORMATION64(y0,y1,y2,y3); \
} while (0)
#endif /* HAVE_NATIVE_64_BIT */
void
serpent_encrypt (const struct serpent_ctx *ctx,
unsigned length, uint8_t * dst, const uint8_t * src)
{
assert( !(length % SERPENT_BLOCK_SIZE));
#if HAVE_NATIVE_64_BIT
if (length & SERPENT_BLOCK_SIZE)
#else
while (length >= SERPENT_BLOCK_SIZE)
#endif
{
uint32_t x0,x1,x2,x3, y0,y1,y2,y3;
unsigned k;
x0 = LE_READ_UINT32 (src);
x1 = LE_READ_UINT32 (src + 4);
x2 = LE_READ_UINT32 (src + 8);
x3 = LE_READ_UINT32 (src + 12);
for (k = 0; ; k += 8)
{
ROUND (0, ctx->keys[k+0], x0,x1,x2,x3, y0,y1,y2,y3);
ROUND (1, ctx->keys[k+1], y0,y1,y2,y3, x0,x1,x2,x3);
ROUND (2, ctx->keys[k+2], x0,x1,x2,x3, y0,y1,y2,y3);
ROUND (3, ctx->keys[k+3], y0,y1,y2,y3, x0,x1,x2,x3);
ROUND (4, ctx->keys[k+4], x0,x1,x2,x3, y0,y1,y2,y3);
ROUND (5, ctx->keys[k+5], y0,y1,y2,y3, x0,x1,x2,x3);
ROUND (6, ctx->keys[k+6], x0,x1,x2,x3, y0,y1,y2,y3);
if (k == 24)
break;
ROUND (7, ctx->keys[k+7], y0,y1,y2,y3, x0,x1,x2,x3);
}
/* Special final round, using two subkeys. */
KEYXOR (y0,y1,y2,y3, ctx->keys[31]);
SBOX7 (y0,y1,y2,y3, x0,x1,x2,x3);
KEYXOR (x0,x1,x2,x3, ctx->keys[32]);
LE_WRITE_UINT32 (dst, x0);
LE_WRITE_UINT32 (dst + 4, x1);
LE_WRITE_UINT32 (dst + 8, x2);
LE_WRITE_UINT32 (dst + 12, x3);
src += SERPENT_BLOCK_SIZE;
dst += SERPENT_BLOCK_SIZE;
length -= SERPENT_BLOCK_SIZE;
}
#if HAVE_NATIVE_64_BIT
FOR_BLOCKS(length, dst, src, 2*SERPENT_BLOCK_SIZE)
{
uint64_t x0,x1,x2,x3, y0,y1,y2,y3;
unsigned k;
x0 = LE_READ_UINT32 (src);
x1 = LE_READ_UINT32 (src + 4);
x2 = LE_READ_UINT32 (src + 8);
x3 = LE_READ_UINT32 (src + 12);
x0 <<= 32; x0 |= LE_READ_UINT32 (src + 16);
x1 <<= 32; x1 |= LE_READ_UINT32 (src + 20);
x2 <<= 32; x2 |= LE_READ_UINT32 (src + 24);
x3 <<= 32; x3 |= LE_READ_UINT32 (src + 28);
for (k = 0; ; k += 8)
{
ROUND64 (0, ctx->keys[k+0], x0,x1,x2,x3, y0,y1,y2,y3);
ROUND64 (1, ctx->keys[k+1], y0,y1,y2,y3, x0,x1,x2,x3);
ROUND64 (2, ctx->keys[k+2], x0,x1,x2,x3, y0,y1,y2,y3);
ROUND64 (3, ctx->keys[k+3], y0,y1,y2,y3, x0,x1,x2,x3);
ROUND64 (4, ctx->keys[k+4], x0,x1,x2,x3, y0,y1,y2,y3);
ROUND64 (5, ctx->keys[k+5], y0,y1,y2,y3, x0,x1,x2,x3);
ROUND64 (6, ctx->keys[k+6], x0,x1,x2,x3, y0,y1,y2,y3);
if (k == 24)
break;
ROUND64 (7, ctx->keys[k+7], y0,y1,y2,y3, x0,x1,x2,x3);
}
/* Special final round, using two subkeys. */
KEYXOR64 (y0,y1,y2,y3, ctx->keys[31]);
SBOX7 (y0,y1,y2,y3, x0,x1,x2,x3);
KEYXOR64 (x0,x1,x2,x3, ctx->keys[32]);
LE_WRITE_UINT32 (dst + 16, x0);
LE_WRITE_UINT32 (dst + 20, x1);
LE_WRITE_UINT32 (dst + 24, x2);
LE_WRITE_UINT32 (dst + 28, x3);
x0 >>= 32; LE_WRITE_UINT32 (dst, x0);
x1 >>= 32; LE_WRITE_UINT32 (dst + 4, x1);
x2 >>= 32; LE_WRITE_UINT32 (dst + 8, x2);
x3 >>= 32; LE_WRITE_UINT32 (dst + 12, x3);
}
#endif /* HAVE_NATIVE_64_BIT */
}
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