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/* arc4.cpp
*
* Copyright (C) 2003 Sawtooth Consulting Ltd.
*
* This file is part of yaSSL.
*
* yaSSL 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.
*
* There are special exceptions to the terms and conditions of the GPL as it
* is applied to yaSSL. View the full text of the exception in the file
* FLOSS-EXCEPTIONS in the directory of this software distribution.
*
* yaSSL 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
*/
/* based on Wei Dai's arc4.cpp from CryptoPP */
#include "runtime.hpp"
#include "arc4.hpp"
#if defined(TAOCRYPT_X86ASM_AVAILABLE) && defined(TAO_ASM)
#define DO_ARC4_ASM
#endif
namespace TaoCrypt {
void ARC4::SetKey(const byte* key, word32 length)
{
x_ = 1;
y_ = 0;
word32 i;
for (i = 0; i < STATE_SIZE; i++)
state_[i] = i;
word32 keyIndex = 0, stateIndex = 0;
for (i = 0; i < STATE_SIZE; i++) {
word32 a = state_[i];
stateIndex += key[keyIndex] + a;
stateIndex &= 0xFF;
state_[i] = state_[stateIndex];
state_[stateIndex] = a;
if (++keyIndex >= length)
keyIndex = 0;
}
}
// local
namespace {
inline unsigned int MakeByte(word32& x, word32& y, byte* s)
{
word32 a = s[x];
y = (y+a) & 0xff;
word32 b = s[y];
s[x] = b;
s[y] = a;
x = (x+1) & 0xff;
return s[(a+b) & 0xff];
}
} // namespace
void ARC4::Process(byte* out, const byte* in, word32 length)
{
if (length == 0) return;
#ifdef DO_ARC4_ASM
if (isMMX) {
AsmProcess(out, in, length);
return;
}
#endif
byte *const s = state_;
word32 x = x_;
word32 y = y_;
if (in == out)
while (length--)
*out++ ^= MakeByte(x, y, s);
else
while(length--)
*out++ = *in++ ^ MakeByte(x, y, s);
x_ = x;
y_ = y;
}
#ifdef DO_ARC4_ASM
#ifdef _MSC_VER
__declspec(naked)
#else
__attribute__ ((noinline))
#endif
void ARC4::AsmProcess(byte* out, const byte* in, word32 length)
{
#ifdef __GNUC__
#define AS1(x) asm(#x);
#define AS2(x, y) asm(#x ", " #y);
#define PROLOG() \
asm(".intel_syntax noprefix"); \
AS2( movd mm3, edi ) \
AS2( movd mm4, ebx ) \
AS2( movd mm5, esi ) \
AS2( movd mm6, ebp ) \
AS2( mov ecx, DWORD PTR [ebp + 8] ) \
AS2( mov edi, DWORD PTR [ebp + 12] ) \
AS2( mov esi, DWORD PTR [ebp + 16] ) \
AS2( mov ebp, DWORD PTR [ebp + 20] )
#define EPILOG() \
AS2( movd ebp, mm6 ) \
AS2( movd esi, mm5 ) \
AS2( movd ebx, mm4 ) \
AS2( mov esp, ebp ) \
AS2( movd edi, mm3 ) \
AS1( emms ) \
asm(".att_syntax");
#else
#define AS1(x) __asm x
#define AS2(x, y) __asm x, y
#define PROLOG() \
AS1( push ebp ) \
AS2( mov ebp, esp ) \
AS2( movd mm3, edi ) \
AS2( movd mm4, ebx ) \
AS2( movd mm5, esi ) \
AS2( movd mm6, ebp ) \
AS2( mov edi, DWORD PTR [ebp + 8] ) \
AS2( mov esi, DWORD PTR [ebp + 12] ) \
AS2( mov ebp, DWORD PTR [ebp + 16] )
#define EPILOG() \
AS2( movd ebp, mm6 ) \
AS2( movd esi, mm5 ) \
AS2( movd ebx, mm4 ) \
AS2( movd edi, mm3 ) \
AS2( mov esp, ebp ) \
AS1( pop ebp ) \
AS1( emms ) \
AS1( ret 12 )
#endif
PROLOG()
AS2( sub esp, 4 ) // make room
AS2( cmp ebp, 0 )
AS1( jz nothing )
AS2( mov [esp], ebp ) // length
AS2( movzx edx, BYTE PTR [ecx + 1] ) // y
AS2( lea ebp, [ecx + 2] ) // state_
AS2( movzx ecx, BYTE PTR [ecx] ) // x
// setup loop
// a = s[x];
AS2( movzx eax, BYTE PTR [ebp + ecx] )
AS1( begin: )
// y = (y+a) & 0xff;
AS2( add edx, eax )
AS2( and edx, 255 )
// b = s[y];
AS2( movzx ebx, BYTE PTR [ebp + edx] )
// s[x] = b;
AS2( mov [ebp + ecx], bl )
// s[y] = a;
AS2( mov [ebp + edx], al )
// x = (x+1) & 0xff;
AS1( inc ecx )
AS2( and ecx, 255 )
//return s[(a+b) & 0xff];
AS2( add eax, ebx )
AS2( and eax, 255 )
AS2( movzx ebx, BYTE PTR [ebp + eax] )
// a = s[x]; for next round
AS2( movzx eax, BYTE PTR [ebp + ecx] )
// xOr w/ inByte
AS2( xor bl, BYTE PTR [esi] )
AS1( inc esi )
// write to outByte
AS2( mov [edi], bl )
AS1( inc edi )
AS1( dec DWORD PTR [esp] )
AS1( jnz begin )
// write back to x_ and y_
AS2( mov [ebp - 2], cl )
AS2( mov [ebp - 1], dl )
AS1( nothing: )
EPILOG()
}
#endif // DO_ARC4_ASM
} // namespace
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