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/* rabbit.c
*
* Copyright (C) 2006-2011 Sawtooth Consulting Ltd.
*
* This file is part of CyaSSL.
*
* CyaSSL 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.
*
* CyaSSL 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
*/
#ifndef NO_RABBIT
#include "rabbit.h"
#include "misc.c"
#ifdef BIG_ENDIAN_ORDER
#define LITTLE32(x) ByteReverseWord32(x)
#else
#define LITTLE32(x) (x)
#endif
#define U32V(x) (word32)(x)
/* Square a 32-bit unsigned integer to obtain the 64-bit result and return */
/* the upper 32 bits XOR the lower 32 bits */
static word32 RABBIT_g_func(word32 x)
{
/* Temporary variables */
word32 a, b, h, l;
/* Construct high and low argument for squaring */
a = x&0xFFFF;
b = x>>16;
/* Calculate high and low result of squaring */
h = (((U32V(a*a)>>17) + U32V(a*b))>>15) + b*b;
l = x*x;
/* Return high XOR low */
return U32V(h^l);
}
/* Calculate the next internal state */
static void RABBIT_next_state(RabbitCtx* ctx)
{
/* Temporary variables */
word32 g[8], c_old[8], i;
/* Save old counter values */
for (i=0; i<8; i++)
c_old[i] = ctx->c[i];
/* Calculate new counter values */
ctx->c[0] = U32V(ctx->c[0] + 0x4D34D34D + ctx->carry);
ctx->c[1] = U32V(ctx->c[1] + 0xD34D34D3 + (ctx->c[0] < c_old[0]));
ctx->c[2] = U32V(ctx->c[2] + 0x34D34D34 + (ctx->c[1] < c_old[1]));
ctx->c[3] = U32V(ctx->c[3] + 0x4D34D34D + (ctx->c[2] < c_old[2]));
ctx->c[4] = U32V(ctx->c[4] + 0xD34D34D3 + (ctx->c[3] < c_old[3]));
ctx->c[5] = U32V(ctx->c[5] + 0x34D34D34 + (ctx->c[4] < c_old[4]));
ctx->c[6] = U32V(ctx->c[6] + 0x4D34D34D + (ctx->c[5] < c_old[5]));
ctx->c[7] = U32V(ctx->c[7] + 0xD34D34D3 + (ctx->c[6] < c_old[6]));
ctx->carry = (ctx->c[7] < c_old[7]);
/* Calculate the g-values */
for (i=0;i<8;i++)
g[i] = RABBIT_g_func(U32V(ctx->x[i] + ctx->c[i]));
/* Calculate new state values */
ctx->x[0] = U32V(g[0] + rotlFixed(g[7],16) + rotlFixed(g[6], 16));
ctx->x[1] = U32V(g[1] + rotlFixed(g[0], 8) + g[7]);
ctx->x[2] = U32V(g[2] + rotlFixed(g[1],16) + rotlFixed(g[0], 16));
ctx->x[3] = U32V(g[3] + rotlFixed(g[2], 8) + g[1]);
ctx->x[4] = U32V(g[4] + rotlFixed(g[3],16) + rotlFixed(g[2], 16));
ctx->x[5] = U32V(g[5] + rotlFixed(g[4], 8) + g[3]);
ctx->x[6] = U32V(g[6] + rotlFixed(g[5],16) + rotlFixed(g[4], 16));
ctx->x[7] = U32V(g[7] + rotlFixed(g[6], 8) + g[5]);
}
/* IV setup */
static void RabbitSetIV(Rabbit* ctx, const byte* iv)
{
/* Temporary variables */
word32 i0, i1, i2, i3, i;
/* Generate four subvectors */
i0 = LITTLE32(*(word32*)(iv+0));
i2 = LITTLE32(*(word32*)(iv+4));
i1 = (i0>>16) | (i2&0xFFFF0000);
i3 = (i2<<16) | (i0&0x0000FFFF);
/* Modify counter values */
ctx->workCtx.c[0] = ctx->masterCtx.c[0] ^ i0;
ctx->workCtx.c[1] = ctx->masterCtx.c[1] ^ i1;
ctx->workCtx.c[2] = ctx->masterCtx.c[2] ^ i2;
ctx->workCtx.c[3] = ctx->masterCtx.c[3] ^ i3;
ctx->workCtx.c[4] = ctx->masterCtx.c[4] ^ i0;
ctx->workCtx.c[5] = ctx->masterCtx.c[5] ^ i1;
ctx->workCtx.c[6] = ctx->masterCtx.c[6] ^ i2;
ctx->workCtx.c[7] = ctx->masterCtx.c[7] ^ i3;
/* Copy state variables */
for (i=0; i<8; i++)
ctx->workCtx.x[i] = ctx->masterCtx.x[i];
ctx->workCtx.carry = ctx->masterCtx.carry;
/* Iterate the system four times */
for (i=0; i<4; i++)
RABBIT_next_state(&(ctx->workCtx));
}
/* Key setup */
void RabbitSetKey(Rabbit* ctx, const byte* key, const byte* iv)
{
/* Temporary variables */
word32 k0, k1, k2, k3, i;
/* Generate four subkeys */
k0 = LITTLE32(*(word32*)(key+ 0));
k1 = LITTLE32(*(word32*)(key+ 4));
k2 = LITTLE32(*(word32*)(key+ 8));
k3 = LITTLE32(*(word32*)(key+12));
/* Generate initial state variables */
ctx->masterCtx.x[0] = k0;
ctx->masterCtx.x[2] = k1;
ctx->masterCtx.x[4] = k2;
ctx->masterCtx.x[6] = k3;
ctx->masterCtx.x[1] = U32V(k3<<16) | (k2>>16);
ctx->masterCtx.x[3] = U32V(k0<<16) | (k3>>16);
ctx->masterCtx.x[5] = U32V(k1<<16) | (k0>>16);
ctx->masterCtx.x[7] = U32V(k2<<16) | (k1>>16);
/* Generate initial counter values */
ctx->masterCtx.c[0] = rotlFixed(k2, 16);
ctx->masterCtx.c[2] = rotlFixed(k3, 16);
ctx->masterCtx.c[4] = rotlFixed(k0, 16);
ctx->masterCtx.c[6] = rotlFixed(k1, 16);
ctx->masterCtx.c[1] = (k0&0xFFFF0000) | (k1&0xFFFF);
ctx->masterCtx.c[3] = (k1&0xFFFF0000) | (k2&0xFFFF);
ctx->masterCtx.c[5] = (k2&0xFFFF0000) | (k3&0xFFFF);
ctx->masterCtx.c[7] = (k3&0xFFFF0000) | (k0&0xFFFF);
/* Clear carry bit */
ctx->masterCtx.carry = 0;
/* Iterate the system four times */
for (i=0; i<4; i++)
RABBIT_next_state(&(ctx->masterCtx));
/* Modify the counters */
for (i=0; i<8; i++)
ctx->masterCtx.c[i] ^= ctx->masterCtx.x[(i+4)&0x7];
/* Copy master instance to work instance */
for (i=0; i<8; i++) {
ctx->workCtx.x[i] = ctx->masterCtx.x[i];
ctx->workCtx.c[i] = ctx->masterCtx.c[i];
}
ctx->workCtx.carry = ctx->masterCtx.carry;
if (iv) RabbitSetIV(ctx, iv);
}
/* Encrypt/decrypt a message of any size */
void RabbitProcess(Rabbit* ctx, byte* output, const byte* input, word32 msglen)
{
/* Encrypt/decrypt all full blocks */
while (msglen >= 16) {
/* Iterate the system */
RABBIT_next_state(&(ctx->workCtx));
/* Encrypt/decrypt 16 bytes of data */
*(word32*)(output+ 0) = *(word32*)(input+ 0) ^
LITTLE32(ctx->workCtx.x[0] ^ (ctx->workCtx.x[5]>>16) ^
U32V(ctx->workCtx.x[3]<<16));
*(word32*)(output+ 4) = *(word32*)(input+ 4) ^
LITTLE32(ctx->workCtx.x[2] ^ (ctx->workCtx.x[7]>>16) ^
U32V(ctx->workCtx.x[5]<<16));
*(word32*)(output+ 8) = *(word32*)(input+ 8) ^
LITTLE32(ctx->workCtx.x[4] ^ (ctx->workCtx.x[1]>>16) ^
U32V(ctx->workCtx.x[7]<<16));
*(word32*)(output+12) = *(word32*)(input+12) ^
LITTLE32(ctx->workCtx.x[6] ^ (ctx->workCtx.x[3]>>16) ^
U32V(ctx->workCtx.x[1]<<16));
/* Increment pointers and decrement length */
input += 16;
output += 16;
msglen -= 16;
}
/* Encrypt/decrypt remaining data */
if (msglen) {
word32 i;
word32 tmp[4];
byte* buffer = (byte*)tmp;
/* Iterate the system */
RABBIT_next_state(&(ctx->workCtx));
/* Generate 16 bytes of pseudo-random data */
tmp[0] = LITTLE32(ctx->workCtx.x[0] ^
(ctx->workCtx.x[5]>>16) ^ U32V(ctx->workCtx.x[3]<<16));
tmp[1] = LITTLE32(ctx->workCtx.x[2] ^
(ctx->workCtx.x[7]>>16) ^ U32V(ctx->workCtx.x[5]<<16));
tmp[2] = LITTLE32(ctx->workCtx.x[4] ^
(ctx->workCtx.x[1]>>16) ^ U32V(ctx->workCtx.x[7]<<16));
tmp[3] = LITTLE32(ctx->workCtx.x[6] ^
(ctx->workCtx.x[3]>>16) ^ U32V(ctx->workCtx.x[1]<<16));
/* Encrypt/decrypt the data */
for (i=0; i<msglen; i++)
output[i] = input[i] ^ buffer[i];
}
}
#endif /* NO_RABBIT */
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