/** Copyright (c) 2002-2009 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: * ** IMPORTANT ** PublishedPartner API's in this file are published to 3rd party developers via the * Symbian website. Changes to these API's should be treated as PublishedAll API changes and the Security TA should be consulted.* RC4 implementation**//** @file @publishedPartner @released */#ifndef __ARC4_H__#define __ARC4_H__#include <streamcipher.h>#ifndef SYMBIAN_ENABLE_SPLIT_HEADERS/** The size of the substitution box (i.e. lookup table) in bytes. */const TInt KSBoxSize = 256;#endif/** Maximum ARC4 key size in bytes. */const TInt KMaxARC4KeyBytes = 256; //2048 bits/** Number of bytes to discard by default from an ARC4 key stream. */const TUint KDefaultDiscardBytes = 768;/*** Implements an RC4-compatible stream cipher that outputs a pseudorandom stream* of bits, having been initialised with a key. **/class CARC4 : public CStreamCipher{public: /** * Constructs an instance of a CARC4 object, and initialises it with a key and * (optionally) the number of initial bytes to discard. Defaults to 256. * * The number of dropped bytes <b>must</b> be agreed with the other * party, with which information is to be exchanged, prior to encipherment. * * @note Several papers have been published indicating that there are weaknesses * in the first bytes of an ARC4 byte stream. A search for "ARC4 * discard" should find these papers. Recommended practice is to drop the first * KDefaultDiscardBytes bytes of the key stream. * * @param aKey The key to use. aKey must be less than or equal to * KRC4MaxKeySizeBytes. * @param aDiscardBytes The number of bytes to drop from the beginning of the key * stream. * @return A pointer to the new CARC4 object. * * @leave KErrKeyNotWeakEnough If the key size is larger than that allowed by the * cipher strength restrictions of the crypto library. * See TCrypto::IsSymmetricWeakEnoughL() */ IMPORT_C static CARC4* NewL(const TDesC8& aKey, TUint aDiscardBytes = KDefaultDiscardBytes); /** * Constructs an instance of a CARC4 object, and initialises it with a key and * (optionally) the number of initial bytes to discard. Defaults to 256. * * The number of dropped bytes <b>must</b> be agreed with the other * party, with which information is to be exchanged, prior to encipherment. * * @see CARC4::NewL() * * @param aKey The key to use. aKey must be less than or equal to * KRC4MaxKeySizeBytes. * @param aDiscardBytes The number of bytes to drop from the beginning of the key * stream. * @return A pointer to the new CARC4 object. * * @leave KErrKeyNotWeakEnough If the key size is larger than that allowed by the * cipher strength restrictions of the crypto library. * See TCrypto::IsSymmetricWeakEnoughL() */ IMPORT_C static CARC4* NewLC(const TDesC8& aKey, TUint aDiscardBytes = KDefaultDiscardBytes);public: virtual void Reset(void); virtual TInt KeySize(void) const;protected: /** * Performs an ARC4 encryption or decryption on supplied data. * * @note ARC4 encryption and decryption are symmetrical. * * @param aData On input, data to be transformed; * on return, transformed data. */ virtual void DoProcess(TDes8& aData); /** @internalComponent */ CARC4();};#endif // __ARC4_H__