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/*
Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
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; version 2 of the License.
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; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
MA 02110-1301 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) #x ";"
#define AS2(x, y) #x ", " #y ";"
#define PROLOG() \
__asm__ __volatile__ \
( \
".intel_syntax noprefix;" \
"push ebx;" \
"push ebp;" \
"mov ebp, eax;"
#define EPILOG() \
"pop ebp;" \
"pop ebx;" \
"emms;" \
".att_syntax;" \
: \
: "c" (this), "D" (out), "S" (in), "a" (length) \
: "%edx", "memory", "cc" \
);
#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] )
#ifdef _MSC_VER
AS1( loopStart: ) // loopStart
#else
AS1( 0: ) // loopStart for some gas (need numeric for jump back
#endif
// 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] )
#ifdef _MSC_VER
AS1( jnz loopStart ) // loopStart
#else
AS1( jnz 0b ) // loopStart
#endif
// write back to x_ and y_
AS2( mov [ebp - 2], cl )
AS2( mov [ebp - 1], dl )
AS1( nothing: )
// inline adjust
AS2( add esp, 4 ) // fix room on stack
EPILOG()
}
#endif // DO_ARC4_ASM
} // namespace
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