diff -r 675a964f4eb5 -r 35751d3474b7 crypto/weakcryptospi/inc/arc4.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/crypto/weakcryptospi/inc/arc4.h Thu Sep 10 14:01:51 2009 +0300 @@ -0,0 +1,115 @@ +/* +* 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 + +#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 must 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 must 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__