/* 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 #ifndef DO_ARC4_ASM void ARC4::Process(byte* out, const byte* in, word32 length) { if (length == 0) return; 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; } #else // DO_ARC4_ASM #ifdef _MSC_VER __declspec(naked) #endif void ARC4::Process(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