/*

 * 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__