Click here to Skip to main content
Click here to Skip to main content
Add your own
alternative version

Build your own cryptographically safe server/client protocol

, 21 Jun 2006 CPOL
This article presents all you need to implement your own secure protocol using variable keysize RSA encryption/decryption, digital signing, multi precision library, Diffie-Hellman key exchange, Rijndael, and more. Everything is converged into a secure IOCP client/server chat server.
// SecureChatIOCP.h: interface for the SecureChatIOCP class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_SecureChatIOCP_H__4093193A_D0A0_4E6A_82FA_65B17A1FEB71__INCLUDED_)
#define AFX_SecureChatIOCP_H__4093193A_D0A0_4E6A_82FA_65B17A1FEB71__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include "IOCPS.h"
#include "MyListCtrl.h"

#include "Rijndael.h" // For encryption/decryption 

#define WM_NEW_CONNECTION	WM_APP + 0x1001
#define WM_LOGG_APPEND	WM_NEW_CONNECTION+1
#define WM_DISCONNECT_CLIENT WM_NEW_CONNECTION+2



#define USE_ENCRYPTION
#define MAXIMUMENCRYPSIZE 31*16
#define ENCRYPTION_BLOCKSIZE 16 
#define SERVER_VERSION "Secure Chat 1.0 BETA"
#define USE_SIGNATURE  // Undefine to remove the "man in middle attack" protection  
//#define _IOCPClientMode_  //define this in your project to make SecureChatIOCP act as the client. 


class SecureChatIOCP : public IOCPS  
{

public: 
	// Send the Text message to all. 
	void SendTextMessage(CString msg);
	// Are we connected to someone ? 
	BOOL IsConnected();		
	CCriticalSection m_StatusLock;
	// Used for ::PostMessage
	HWND m_hWnd;

	// The Public Key P.. Used only in ClientMode. 
#ifdef _IOCPClientMode_ 
	DWORD* m_pPublicKeyP;
	UINT m_nSizePublicKey;
	CString m_sUserName; 
#endif

	SecureChatIOCP();
	virtual ~SecureChatIOCP();
	// Send an Error Message to Client. 
	BOOL SendErrorMessageTo(int iClientID, CString sMsg);
	// Send a Message to a Client. 
	BOOL SendTextMessageTo(int iClientID, CString sMsg);
	// The function handling decrypted messsages. 
	inline void ProcessPayload(CIOCPBuffer *pOverlapBuff,int nSize,ClientContext *pContext);
	// A client have Disconnected. 
	virtual void NotifyDisconnectedClient(ClientContext *pContext);
	// A new ClientContext is made. 
	virtual void NotifyNewClientContext(ClientContext *pContext);
	// A new Connection has arrived. 
	virtual void NotifyNewConnection(ClientContext *pcontext);
	// A Package have arrived. 
	virtual void NotifyReceivedPackage(CIOCPBuffer *pOverlapBuff,int nSize,ClientContext *pContext);
	// The package sucessfully sended. 
	virtual void NotifyWriteCompleted(ClientContext *pContext, DWORD dwIoSize, CIOCPBuffer *pOverlapBuff);
	// An ClientContext is going to be deleted insert more cleanup code if nesseary.  
	virtual void NotifyContextRelease(ClientContext *pContext);
	// Called to do some work. 
	virtual inline void ProcessJob(JobItem *pJob,IOCPS* pServer);
	// Called to add the msg to the log. 
	virtual void AppendLog(CString msg);

protected:	
	// Send an special two buffered package 
	void BuildAndSend(ClientContext *pContext, BYTE _pkgtype, CString str1,CString str2);
	void BuildAndSend(ClientContext *pContext, BYTE _pkgtype, CString str1,UINT nBufferSize2, const BYTE *_pBuff2 );
	void BuildAndSend(ClientContext *pContext, BYTE _pkgtype,  UINT nBufferSize1, const BYTE *_pBuff1,  UINT nBufferSize2, const BYTE *_pBuff2);	
	// Reads the package build with BuildAndSend(..) 
	void ReadPkg(CIOCPBuffer *pBuff, UINT &nSize,BYTE** _pBuff1,  UINT &nSize2,BYTE** _pBuff2, ClientContext *pContext);
	// Computes a signature form Sha1Hash(A+B) and sends it to the client. 
	inline void ComputeAndSendSignature(ClientContext *pContext);	
	// Compute the secure exchanged Session key. 
	inline BOOL ComputeAndSetSessionKey(CIOCPBuffer *pOverlapBuff, int nSize, ClientContext *pContext);
	// Computes the public key (Diffie-Hellman) and sends the key as _keytype (is  PKG_PUBLIC_KEYA or PKG_PUBLIC_KEYB)
	inline void ComputeAndSendPublicKey(ClientContext *pContext, BYTE _keytype);
	// Computes the PublicKeyA and send it (uses ComputeAndSendPublicKey(..))
	inline void ComputeAndSendPublicKeyA(ClientContext* pContext);
	// Computes the PublicKeyB and send it (uses ComputeAndSendPublicKey(..))
	inline void ComputeAndSendPublicKeyB(ClientContext* pContext);
	// Builds a Public key package and sends it to the client. 
	inline void SendPublicKey(ClientContext *pContext, BYTE _keytype, DWORD *_pPublicKey,UINT nPublicKeySize);
	// Reads a Key form package returns NULL if error. 
	inline DWORD* ReadPublicKeyFromBuffer(CIOCPBuffer* pBuff, UINT &nKeySize,ClientContext *pContext);
	// Sends a text message to the Client. 	
	BOOL SendTextMessageTo(ClientContext* pContext, CString sMsg);

	// Encrypt/Decrypt functions.  
	inline int MaxEncyptedPayloadSize(int iMaxLength);	
	CIOCPBuffer* DeCryptBuffer(CIOCPBuffer *pBuff, ClientContext *pContext);
	CIOCPBuffer* EnCryptBuffer(CIOCPBuffer *pBuff, ClientContext *pContext);

	// Package handlers. 	
	void OnPKG_ERRORMSG(CIOCPBuffer *pOverlapBuff,int nSize,ClientContext *pContext);
	void OnPKG_TEXT_TO_ALL(CIOCPBuffer *pOverlapBuff,int nSize,ClientContext *pContext);
	void OnPKG_USERNAME_PASSWORD(CIOCPBuffer *pOverlapBuff,int nSize,ClientContext *pContext);
	void OnPKG_PUBLIC_KEYP(CIOCPBuffer *pOverlapBuff,int nSize,ClientContext *pContext);
	void OnPKG_PUBLIC_KEYA(CIOCPBuffer *pOverlapBuff,int nSize,ClientContext *pContext);
	void OnPKG_PUBLIC_KEYB(CIOCPBuffer *pOverlapBuff,int nSize,ClientContext *pContext);
	void OnPKG_SIGNATURE(CIOCPBuffer *pOverlapBuff,int nSize,ClientContext *pContext);

private:
	static const DWORD m_DSAKeypubN[64];
#ifndef _IOCPClientMode_
	static const DWORD m_DSAKeypubD[64];
#endif
	static const DWORD m_DSAKeypubE;
};

#endif // !defined(AFX_SecureChatIOCP_H__4093193A_D0A0_4E6A_82FA_65B17A1FEB71__INCLUDED_)

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Share

About the Author

spinoza
Program Manager
Sweden Sweden
Amin Gholiha.
Education:
- Master of Science in Information Technology.
- Degree of Master of Education.
Knowledge/interest: programming (.NET,Visual, C#/C++), neural network, mathematical modeling, signal processing, sequence analysis, pattern recognition,robot technology, system design, security and business management systems. For business proposal email Gholiha@rocketmail.com, all other emails will be ignored.
Current Work:
Project Manager
www.easysoft.nu (the best free e-signature tool)

| Advertise | Privacy | Mobile
Web01 | 2.8.141022.2 | Last Updated 21 Jun 2006
Article Copyright 2006 by spinoza
Everything else Copyright © CodeProject, 1999-2014
Terms of Service
Layout: fixed | fluid