/*

* Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the License "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

* (c) 1999-2003 Symbian Ltd

*

*/

/**

 @file

 @publishedAll

 @released

*/

#ifndef __RANDOM_H__

#define __RANDOM_H__

#include <e32base.h>

class CRandom : public CBase

/**

 * @publishedAll

 * @released

 */

	{

public:

	/**

	 * Implementations of this method should fill the passed

	 * buffer with the generated pseudo-random data up to the

	 * current length, discarding any current contents. The 

	 * implementations should leave with KErrNotSecure when 

	 * the generated random data is not secure enough. 

	 *

	 * @param aDest The buffer to fill with random data

	 * @leave KErrNotSecure Random data generated is not 

	 *        secure enough for crytographic operations

	 *        otherwise, leaves with any other system wide error code.

	 *

	 */

	virtual void GenerateBytesL(TDes8& aDest) = 0;

protected:

	IMPORT_C CRandom(void);

private:

	CRandom(const CRandom&);

	CRandom& operator=(const CRandom&);

	};

/**

 *

 * Sets a pseudo-random number generator implementation to use for this thread.

 * 

 * @param aRNG The pseudo-random number generator to use.

 *

 */

IMPORT_C void SetThreadRandomL(CRandom* aRNG);

/**

 *

 * Sets a pseudo-random number generator implementation to use

 * for this thread, placing it on the cleanup stack.

 * 

 * @param aRNG The pseudo-random number generator to use.

 *

 */

IMPORT_C void SetThreadRandomLC(CRandom* aRNG);

/** @internalAll */

void DeleteThreadRandom(TAny* aPtr);

/**

 *

 * Destroys the currently installed random number generator

 * that is in use for this thread.

 *

 */

IMPORT_C void DestroyThreadRandom(void);

/**

 *

 * Generates pseudo-random data.

 * Fills the provided buffer up to its current length,

 * discarding any data that it may currently contain.

 *

 * @param aDest The buffer to fill with random data

 * @leave KErrNotSecure The random data generated is  

 *        not secure enough for cryptographic operations

 *        otherwise, leaves with any other system wide error codes. 

 *

 */

IMPORT_C void GenerateRandomBytesL(TDes8& aDest);

class CRandomShim;

class CSystemRandom : public CRandom

/**

 *

 * This default pseudo-random number generator uses system state 

 * to generate entropy for the generation of random numbers.

 *

 * @publishedAll

 * @released

 *

 */

	{

public:

	/**

	 *

	 * Constructs a new pseudo-random number generator.

	 *

	 * @return A ready-to-use random number generator.

	 */

	IMPORT_C static CSystemRandom* NewL(void);

	/**

	 *

	 * Constructs a new pseudo-random number generator,

	 * and places it on the cleanup stack.

	 *

	 * @return A ready-to-use random number generator.

	 *

	 */

	IMPORT_C static CSystemRandom* NewLC(void);

	/**

	 *

	 * Implements the contract as specified in the base class,  CRandom, filling the buffer

	 * supplied with random data  up to its current length, discarding its current content.

	 * It will leave with KErrNotSecure when the generated random data is not secure enough.

	 *

	 * @param aDest The buffer to which to write random data

	 * @leave KErrNotSecure The generated random data is not secure enough for cryptographic operations 

	 *        otherwise, leaves with any other system wide error codes.

	 *        

	 */

	virtual void GenerateBytesL(TDes8& aDest);

	~CSystemRandom();

private:

	CSystemRandom(void);

	CSystemRandom(const CSystemRandom&);

	CSystemRandom& operator=(const CSystemRandom&);

	void ConstructL();

	CRandomShim *iShim;

	};

class TRandom

/**

 *

 * The user interface to the random number generator.

 *

 * @publishedAll

 * @released

 */

	{

public:

	/**

	 * 

	 * Fills the provided buffer with pseudo-random data up to its current length, 

	 * discarding any current content.

	 *

	 * This method will not return secure random numbers for some time after the phone boot-up. Because,

	 * pseudo-random number generator will take some time to attain a secure state by collecting enough 

	 * entropy samples after the boot-up. Till that time, the pseudo-random numbers generated may not be

	 * cryptographically secure and there is no way to get to know about it with this API. 

	 * So, if explcit notification on the strength of the random numbers is necessary, use TRandom::SecureRandomL.

	 *

	 * @param aDestination The buffer in which to write the random data.

	 * @deprecated Use RandomL() instead

	 * @panic This function can panic under low memory conditions

	 *

	 */

	IMPORT_C static void Random(TDes8& aDestination);

	/**	

	 * 

	 * Fills the provided buffer with pseudo-random data up to its current length,

	 * discarding any current content.

	 *

	 * This method will not return secure random numbers for some time after the phone boot-up. Because,

     * pseudo-random number generator will take some time to attain a secure state by collecting enough 

     * entropy samples after the boot-up. Till that time, the pseudo-random numbers generated may not be

     * cryptographically secure and there is no way to get to know about it with this API. 

     * So, if explcit notification on the strength of the random numbers is necessary, use TRandom::SecureRandomL.

	 *

	 * @param aDestination The buffer in which to write the random data.

	 * @leave This function can leave under low memory conditions

	 *

	 */

	IMPORT_C static void RandomL(TDes8& aDestination);

	/**

	 * 

	 * Fills the provided buffer with the pseudo-random data up to its current length, discarding any current

	 * content of the descriptor. When this method returns normally (with out leave), the system state is secure

	 * and hence the random numbers generated are cryptographically secure as well. When this method leaves with

	 * the error code KErrNotSecure, the system internal state is not secure and hence the random numbers too.

	 * 

	 * Though this method leaves when the system internal state is not secure, still the descriptor will be filled 

	 * with pseudo-random bytes. This random data may or may not be secure enough. Recommended to treat these numbers 

	 * as not secure.

	 *

	 * @param aDestination The buffer in which to write the random data.

	 * @leave KErrNotSecure The generated random numbers is not secure enough for cryptographic operations.

	 *        Otherwise, leaves with some other system wide error codes.

	 *

	 */

	IMPORT_C static void SecureRandomL(TDes8& aDestination);

	};

class RRandomSession:public RSessionBase

/**

 *

 * The client interface to the system random number generator. End

 * users should use TRandom instead of this interface.

 *

 * @publishedAll

 * @released

 */

	{

public:

	IMPORT_C RRandomSession(void);

	/**

	 * 

	 * Fills the provided buffer with pseudo-random data up to its

	 * current length, discarding any current content.

	 *

	 * @param aDestination The buffer in to which to write the random data 

	 *

	 */

	IMPORT_C TInt GetRandom(TDes8& aDestination);

	/**

	 *

	 * Opens a new session with the random number generator.

	 *

	 */

	IMPORT_C void ConnectL(void);

	};

#endif // __RANDOM_H__