aesengine.h

algorithm provide basic encryption/decryption using AES for with Secret Key.

// AESEngine.h: interface for the AESEngine class.
//
//////////////////////////////////////////////////////////////////////

//=============================================================================
// This file contains the implimentation of class AES Engine class.
// 
// @Copy right: C-Sam Incorporated, Chicago (c) 2002 All Rights Reserved
//=============================================================================
//
//-------------------------------------
// Version History
//-------------------------------------
// Version	:  1.0
// Author	:  arun.kumar
// Date    	:  12.12.2005
// Comment 	:  Initial release
// ------------------------------------
// Version	:  1.1
// Author	:  arun.kumar
// Date    	:  26.02.2008
// Comment 	:  Support for CBC and ECB mode being implemented
//=============================================================================


/**
* an implementation of the AES (Rijndael)), from FIPS-197.
* <p>
* For further details see: <a href="http://csrc.nist.gov/encryption/aes/">http://csrc.nist.gov/encryption/aes/</a>.
*
* This implementation is based on optimizations from Dr. Brian Gladman's paper and C code at
* <a href="http://fp.gladman.plus.com/cryptography_technology/rijndael/">http://fp.gladman.plus.com/cryptography_technology/rijndael/</a>
*
* There are three levels of tradeoff of speed vs memory
* Because java has no preprocessor), they are written as three separate classes from which to choose
*
* The fastest uses 8Kbytes of static tables to precompute round calculations), 4 256 word tables for encryption
* and 4 for decryption.
*
* The middle performance version uses only one 256 word table for each), for a total of 2Kbytes),
* adding 12 rotate operations per round to compute the values contained in the other tables from
* the contents of the first
*
* The slowest version uses no static tables at all and computes the values in each round
* <p>
* This file contains the fast version with 8Kbytes of static tables for round precomputation
*
*/
#include <STDIO.H>

#ifndef AFX_AESENGINE_H__
#define AFX_AESENGINE_H__

typedef	unsigned char byte;
typedef	unsigned int uint;


#define	MAXROUNDS	14
#define	MAXKC		64
#define BLOCK_SIZE	64
#define BLOCK_BITS	128

#define AES_BLOCK_SIZE 16

#define CBC_MODE	151
#define ECB_MODE	152


class AESEngine  
{
public:
	AESEngine();
	~AESEngine();
	
	int encrypt( byte plainData[], int plainDataLength, byte*& encryptedData );

	int decrypt( byte encryptedData[], int encryptedDataLength, byte*& decryptedData );

	void init( byte key[], int keyLength, int mode );

private:

//--------------------------------------------------------------------------
// cipher params
//--------------------------------------------------------------------------
    static const byte Logtable[];

	static const byte Alogtable[];

	static const byte S[]; 

	static const byte Si[];

	static const int rcon[];

//--------------------------------------------------------------------------
// instance variables
//--------------------------------------------------------------------------
	
    int			ROUNDS;
    unsigned int			workingKey_[ MAXROUNDS + 1 ] [ 4 ];
    int			A0;
    int			A1;
    int			A2;
    int			A3;
    bool	    forEncryption_;
	int			keyLength_;
	byte		cbcV_[ AES_BLOCK_SIZE ];
	int			mode_;
//--------------------------------------------------------------------------

private:

//--------------------------------------------------------------------------
// cipher methods
//--------------------------------------------------------------------------

	byte mul0x2( int b );

	byte mul0x3( int b );

	byte mul0x9( int b );

	byte mul0xb( int b );

	byte mul0xd( int b );

	byte mul0xe( int b );

	void KeyAddition( int rk[] );
	
	int  shift( int r, int shift );
	
	void ShiftRow();
	
	void InvShiftRow();

	int  applyS( int r, const byte* box );
	
	void Substitution( const byte* box );
	
	void MixColumn();

	void InvMixColumn();
	
	void generateWorkingKey( byte key[] );

	int processBlock( byte in[], int inOff, byte out[], int outOff);

	void unpackBlock( byte bytes[], int off );
	
	void packBlock( byte bytes[], int off );

	void encryptBlock( int rk[][4] );

	void decryptBlock( int rk[][4] );

};

#endif // AFX_AESENGINE_H__