/*
Module : Helix.H
Purpose: C++ class to encapsulate the Helix Encryption and Authentication algorithm as presented in 
         a November 2003 Dr. Dobb's Journal article by Niels Ferguson and Bruce Schneier. For
         further information please refer to the article and / or the web site for it at
         http://www.macfergus.com/helix
Created: PJN / 29-11-2003



Copyright (c) 2003 - 2004 by PJ Naughter.  (Web: www.naughter.com, Email: pjna@naughter.com)

All rights reserved.

Copyright / Usage Details:

You are allowed to include the source code in any product (commercial, shareware, freeware or otherwise) 
when your product is released in binary form. You are allowed to modify the source code in any way you want 
except you cannot modify the copyright details at the top of each module. If you want to distribute source 
code with your application, then you are only allowed to distribute versions released by the author. This is 
to maintain a single distribution point for the source code. 

*/

#ifndef __HELIX_H__
#define __HELIX_H__


//Class which encapsulates a "nonce" as used by the Helix algorithm
class CHelixNonce
{
public:
//Constructors / Destructors
  CHelixNonce();

//Member variables
  BYTE m_Data[16];
};

//Class which encapsulates a "Message Authentication Code" as used by the Helix algorithm
class CHelixMAC
{
public:
//Constructors / Destructors
  CHelixMAC();

//Methods
  friend operator==(const CHelixMAC& mac1, const CHelixMAC& mac2);

//Member variables
  BYTE m_Data[16];
};

//Class which encapsulates the actual Helix encryption / decryption algorithm
class CHelix
{
public:
//Constructors / Destructors
  CHelix();

//Methods
  BOOL SetKey(const BYTE* pbyKey, DWORD dwKeyLength);
  BOOL Encrypt(const BYTE* pbyPlainText, DWORD dwPlainTextSize, const CHelixNonce& nonce, BYTE* pbyCipherText, CHelixMAC& mac);
  BOOL Decrypt(const BYTE* pbyCipherText, DWORD dwCipherTextSize, const CHelixNonce& nonce, const CHelixMAC& mac, BYTE* pbyPlainText);

protected:
//Methods
  inline void Block(DWORD X0, DWORD P, DWORD X1);
  void Start(const CHelixNonce& nonce);
  void Finish(DWORD lnm4, CHelixMAC& Mac);

//Member variables
	DWORD m_Z[5];
  DWORD m_K[8];
  DWORD m_X1[8];
  int   m_dwKLen;
  int   m_i8;
};


#endif //__HELIX_H__