/*

* Copyright (c) 2006-2009 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: 

*

*/

#include "desimpl.h"

#include "destables.h"

#include "common/inlines.h"

#include "des.inl"

#include "pluginconfig.h"

#include "symmetriccipherimpl.h"

#include <cryptostrength.h>

//	bit 0 is left-most in byte

static const TInt bytebit[] = {0200,0100,040,020,010,04,02,01};

using namespace SoftwareCrypto;

/* CDesImpl */

CDesImpl::CDesImpl(

	TUint8 aBlockBytes,

	TUid aCryptoMode,

	TUid aOperationMode,

	TUid aPadding) :

	CSymmetricBlockCipherImpl(aBlockBytes, aCryptoMode, aOperationMode, aPadding)

	{

	}

CDesImpl* CDesImpl::NewL(const CKey& aKey, TUid aCryptoMode, TUid aOperationMode, TUid aPadding)

	{

	CDesImpl* self = CDesImpl::NewLC(aKey, aCryptoMode, aOperationMode, aPadding);

	CleanupStack::Pop(self);

	return self;

	}

CDesImpl* CDesImpl::NewLC(const CKey& aKey, TUid aCryptoMode, TUid aOperationMode, TUid aPadding)

	{

	CDesImpl* self = new(ELeave) CDesImpl(KDesBlockBytes, aCryptoMode, aOperationMode, aPadding);

	CleanupStack::PushL(self);

	self->ConstructL(aKey);

	const TDesC8& keyContent = aKey.GetTDesC8L(KSymmetricKeyParameterUid);

	TCrypto::IsSymmetricWeakEnoughL(BytesToBits(keyContent.Size()) - keyContent.Size());

	return self;

	}

CDesImpl::~CDesImpl()

	{

	// make sure key information isn't visible to other processes if the

	// page is reused.

	Mem::FillZ(&iK, sizeof(iK));

	}

void CDesImpl::ConstructL(const CKey& aKey)

	{

	CSymmetricBlockCipherImpl::ConstructL(aKey);

	SetKeySchedule();

	}		

CExtendedCharacteristics* CDesImpl::CreateExtendedCharacteristicsL()

	{

	// All Symbian software plug-ins have unlimited concurrency, cannot be reserved

	// for exclusive use and are not CERTIFIED to be standards compliant.

	return CExtendedCharacteristics::NewL(KMaxTInt, EFalse);

	}

const CExtendedCharacteristics* CDesImpl::GetExtendedCharacteristicsL()

	{

	return CDesImpl::CreateExtendedCharacteristicsL();

	}

TUid CDesImpl::ImplementationUid() const

	{

	return KCryptoPluginDesUid;

	}

TBool CDesImpl::IsValidKeyLength(TInt aKeyBytes) const

	{

	return (aKeyBytes == KDesKeyBytes);

	}

TInt CDesImpl::GetKeyStrength() const

	{

	// parity bits are excluded

	return BytesToBits(KDesKeyBytes - 8);

	}	

void CDesImpl::TransformEncrypt(

	TUint8* aBuffer,

	TUint aNumBlocks)

	{

	for (TInt i = 0; i < aNumBlocks; ++i)

		{		

		ModeEncryptStart(aBuffer);

		TUint32 l, r;

		// Split the block into 2 word-sized big endian portions

		GetBlockBigEndian(aBuffer, l, r);

		IPerm(l,r);

		DoTransform(l, r, iK);		

		FPerm(l,r);

		// Put the portions back into the block as little endian

		PutBlockBigEndian(aBuffer, r, l);

		ModeEncryptEnd(aBuffer);

		aBuffer += KDesBlockBytes;

		}

	}	

void CDesImpl::TransformDecrypt(

	TUint8* aBuffer,

	TUint aNumBlocks)

	{

	for (TInt i = 0; i < aNumBlocks; ++i)

		{		

		ModeDecryptStart(aBuffer);

		TUint32 l, r;

		// Split the block into 2 word-sized big endian portions

		GetBlockBigEndian(aBuffer, l, r);

		IPerm(l,r);

		DoTransform(l, r, iK);		

		FPerm(l,r);

		// Put the portions back into the block as little endian

		PutBlockBigEndian(aBuffer, r, l);

		ModeDecryptEnd(aBuffer);

		aBuffer += KDesBlockBytes;

		}

	}

void CDesImpl::SetKeySchedule()

	{

	if (iCryptoMode.iUid == KCryptoModeEncrypt)

		{

		SetEncryptKeySchedule(*iKey, iK);

		}

	else 

		{

		ASSERT(iCryptoMode.iUid == KCryptoModeDecrypt);

		SetDecryptKeySchedule(*iKey, iK);

		}	

	}		

void CDesImpl::DoTransform(TUint32& l, TUint32& r, const TUint32* aKeySchedule)

	{

	TInt i = 0;

	for (; i<8; i++)

		{

		TUint32 work = rotrFixed(r, 4U) ^ aKeySchedule[4*i+0];

		l ^= DES_TABLE::sbox[6][(work) & 0x3f]

		  ^  DES_TABLE::sbox[4][(work >> 8) & 0x3f]

		  ^  DES_TABLE::sbox[2][(work >> 16) & 0x3f]

		  ^  DES_TABLE::sbox[0][(work >> 24) & 0x3f];

		work = r ^ aKeySchedule[4*i+1];

		l ^= DES_TABLE::sbox[7][(work) & 0x3f]

		  ^  DES_TABLE::sbox[5][(work >> 8) & 0x3f]

		  ^  DES_TABLE::sbox[3][(work >> 16) & 0x3f]

		  ^  DES_TABLE::sbox[1][(work >> 24) & 0x3f];

		work = rotrFixed(l, 4U) ^ aKeySchedule[4*i+2];

		r ^= DES_TABLE::sbox[6][(work) & 0x3f]

		  ^  DES_TABLE::sbox[4][(work >> 8) & 0x3f]

		  ^  DES_TABLE::sbox[2][(work >> 16) & 0x3f]

		  ^  DES_TABLE::sbox[0][(work >> 24) & 0x3f];

		work = l ^ aKeySchedule[4*i+3];

		r ^= DES_TABLE::sbox[7][(work) & 0x3f]

		  ^  DES_TABLE::sbox[5][(work >> 8) & 0x3f]

		  ^  DES_TABLE::sbox[3][(work >> 16) & 0x3f]

		  ^  DES_TABLE::sbox[1][(work >> 24) & 0x3f];

		}

	}	

void CDesImpl::SetEncryptKeySchedule(const TDesC8& aKey, TUint32* aKeySchedule)

	{

	TInt i=0, j=0, l=0, m=0;

//	Form a byte array from aKey, taking endianess into account (little->big)	

	TUint8 key[8];								//	For big endian byte array	

	Mem::Copy(&key, &aKey[0], 8);

	TUint8 buffer[56+56+8];

	TUint8* const pc1m = &buffer[0];			/* place to modify pc1 into */

	TUint8* const pcr = pc1m + 56;				/* place to rotate pc1 into */

	TUint8* const ks = pcr + 56;

	for (j=0; j<56; j++) 

		{/* convert pc1 to bits of key */

		l = DES_TABLE::pc1[j]-1;				/* integer bit location  */

		m = l & 07;								/* find bit              */

		pc1m[j]=(key[l>>3] &					/* find which key byte l is in */

			bytebit[m])							/* and which bit of that byte */

			? (TUint8)1 : (TUint8)0;			/* and store 1-bit result */

		}

	for (i=0; i<16; i++) 

		{/* key chunk for each iteration */

		Mem::FillZ(ks,8);							/* Clear key schedule */

		for (j=0; j<56; j++)

		/*	rotate pc1 the right amount */

			pcr[j] = pc1m[(l=j+DES_TABLE::totrot[i])<(j<28? 28 : 56) ? l: l-28];

		/* rotate left and right halves independently */

		for (j=0; j<48; j++)

			{/* select bits individually */

			/* check bit that goes to ks[j] */

			if (pcr[DES_TABLE::pc2[j]-1])

				{/* mask it in if it's there */

				l= j % 6;

				ks[j/6] |= bytebit[l] >> 2;

				}

			}

		/* Now convert to odd/even interleaved form for use in F */

		(*(aKeySchedule+(2*i))) = ((TUint32)ks[0] << 24)

			| ((TUint32)ks[2] << 16)

			| ((TUint32)ks[4] << 8)

			| ((TUint32)ks[6]);

		(*(aKeySchedule+(2*i+1))) = ((TUint32)ks[1] << 24)

			| ((TUint32)ks[3] << 16)

			| ((TUint32)ks[5] << 8)

			| ((TUint32)ks[7]);

		}		

	}

void CDesImpl::SetDecryptKeySchedule(const TDesC8& aKey, TUint32* aKeySchedule)

	{

	SetEncryptKeySchedule(aKey, aKeySchedule);

	ReverseKeySchedule(aKeySchedule);

	}