/** 
 * @file llxorcipher.h
 *
 * $LicenseInfo:firstyear=2003&license=viewergpl$
 * 
 * Copyright (c) 2003-2009, Linden Research, Inc.
 * 
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
 * ("GPL"), unless you have obtained a separate licensing agreement
 * ("Other License"), formally executed by you and Linden Lab.  Terms of
 * the GPL can be found in doc/GPL-license.txt in this distribution, or
 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
 * 
 * There are special exceptions to the terms and conditions of the GPL as
 * it is applied to this Source Code. View the full text of the exception
 * in the file doc/FLOSS-exception.txt in this software distribution, or
 * online at
 * http://secondlifegrid.net/programs/open_source/licensing/flossexception
 * 
 * By copying, modifying or distributing this software, you acknowledge
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 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
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 * $/LicenseInfo$
 */

#ifndef LLXORCIPHER_H
#define LLXORCIPHER_H

#include "llcipher.h"

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Class LLXORCipher
//
// Implementation of LLCipher which encrypts using a XOR pad.
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

class LLXORCipher : public LLCipher
{
public:
	LLXORCipher(const U8* pad, U32 pad_len);
	LLXORCipher(const LLXORCipher& cipher);
	virtual ~LLXORCipher();
	LLXORCipher& operator=(const LLXORCipher& cipher);

	// Cipher functions
	/*virtual*/ U32 encrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len);
	/*virtual*/ U32 decrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len);
	/*virtual*/ U32 requiredEncryptionSpace(U32 src_len) const;

	// special syntactic-sugar since xor can be performed in place.
	BOOL encrypt(U8* buf, U32 len) { return encrypt((const U8*)buf, len, buf, len); }
	BOOL decrypt(U8* buf, U32 len) { return decrypt((const U8*)buf, len, buf, len); }

#ifdef _DEBUG
	// This function runs tests to make sure the crc is
	// working. Returns TRUE if it is.
	static BOOL testHarness();
#endif

protected:
	void init(const U8* pad, U32 pad_len);
	U8* mPad;
	U8* mHead;
	U32 mPadLen;
};

#endif
