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/**
* @file llxorcipher.cpp
* @brief Implementation of LLXORCipher
*
* $LicenseInfo:firstyear=2003&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This 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;
* version 2.1 of the License only.
*
* This 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#include "linden_common.h"
#include "llxorcipher.h"
#include "llerror.h"
///----------------------------------------------------------------------------
/// Class LLXORCipher
///----------------------------------------------------------------------------
LLXORCipher::LLXORCipher(const U8* pad, U32 pad_len) :
mPad(NULL),
mHead(NULL),
mPadLen(0)
{
init(pad, pad_len);
}
// Destroys the object
LLXORCipher::~LLXORCipher()
{
init(NULL, 0);
}
LLXORCipher::LLXORCipher(const LLXORCipher& cipher) :
mPad(NULL),
mHead(NULL),
mPadLen(0)
{
init(cipher.mPad, cipher.mPadLen);
}
LLXORCipher& LLXORCipher::operator=(const LLXORCipher& cipher)
{
if(this == &cipher) return *this;
init(cipher.mPad, cipher.mPadLen);
return *this;
}
U32 LLXORCipher::encrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len)
{
if(!src || !src_len || !dst || !dst_len || !mPad) return 0;
U8* pad_end = mPad + mPadLen;
U32 count = src_len;
while(count--)
{
*dst++ = *src++ ^ *mHead++;
if(mHead >= pad_end) mHead = mPad;
}
return src_len;
}
U32 LLXORCipher::decrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len)
{
// xor is a symetric cipher, thus, just call the other function.
return encrypt(src, src_len, dst, dst_len);
}
U32 LLXORCipher::requiredEncryptionSpace(U32 len) const
{
return len;
}
void LLXORCipher::init(const U8* pad, U32 pad_len)
{
if(mPad)
{
delete [] mPad;
mPad = NULL;
mPadLen = 0;
}
if(pad && pad_len)
{
mPadLen = pad_len;
mPad = new U8[mPadLen];
if (mPad != NULL)
{
memcpy(mPad, pad, mPadLen); /* Flawfinder : ignore */
}
}
mHead = mPad;
}
#ifdef _DEBUG
// static
bool LLXORCipher::testHarness()
{
const U32 PAD_LEN = 3;
const U8 PAD[] = "abc";
const S32 MSG_LENGTH = 12;
const char MESSAGE[MSG_LENGTH+1] = "gesundheight"; /* Flawfinder : ignore */
U8 encrypted[MSG_LENGTH];
U8 decrypted[MSG_LENGTH];
LLXORCipher cipher(PAD, PAD_LEN);
cipher.encrypt((U8*)MESSAGE, MSG_LENGTH, encrypted, MSG_LENGTH);
cipher.decrypt(encrypted, MSG_LENGTH, decrypted, MSG_LENGTH);
if(0 != memcmp((void*)MESSAGE, decrypted, MSG_LENGTH)) return false;
return true;
}
#endif
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