sl@0: /*
sl@0: * Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: * All rights reserved.
sl@0: * This component and the accompanying materials are made available
sl@0: * under the terms of the License "Eclipse Public License v1.0"
sl@0: * which accompanies this distribution, and is available
sl@0: * at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: *
sl@0: * Initial Contributors:
sl@0: * Nokia Corporation - initial contribution.
sl@0: *
sl@0: * Contributors:
sl@0: *
sl@0: * Description: 
sl@0: *
sl@0: */
sl@0: 
sl@0: 
sl@0: /**
sl@0:  @file
sl@0: */
sl@0: 
sl@0: #include "pkcs5kdf.h"
sl@0: 
sl@0: /* Before complaining about the variable names in this file, 
sl@0:  * read the pkcs5 spec and all will become clear.
sl@0:  */
sl@0: 
sl@0: EXPORT_C void TPKCS5KDF::DeriveKeyL(TDes8& aKey, const TDesC8& aPasswd, const TDesC8& aSalt, 
sl@0: 	const TUint aIterations)
sl@0: {
sl@0: 	CSHA1* sha1 = CSHA1::NewL();
sl@0: 	CleanupStack::PushL(sha1);
sl@0: 	CHMAC* hmac = CHMAC::NewL(aPasswd, sha1);
sl@0: 	CleanupStack::Pop(sha1); //hmac now owns it
sl@0: 	CleanupStack::PushL(hmac);
sl@0: 
sl@0: 	TUint hashBytes = hmac->HashSize();
sl@0: 	TUint c = aIterations;
sl@0: 	TUint l = aKey.Length() / hashBytes; 
sl@0: 	if(aKey.Length() % hashBytes != 0) //round up if mod !=0
sl@0: 		{
sl@0: 		l+=1;
sl@0: 		}
sl@0: 	TUint r = aKey.Length() - (l-1) * hashBytes; //r == length of last block
sl@0: 	
sl@0: 	HBufC8* TiTemp = HBufC8::NewLC(hashBytes);
sl@0: 	TUint32* Ti = (TUint32*)(TiTemp->Ptr());
sl@0: 	aKey.SetLength(0); //we've already saved the length we want
sl@0: 
sl@0: 	HBufC8* STemp = HBufC8::NewLC(aSalt.Length() + sizeof(TUint32));
sl@0: 	TUint32* S = (TUint32*)(STemp->Ptr());
sl@0: 
sl@0: 	HBufC8* UiTemp = HBufC8::NewLC(hashBytes);
sl@0: 	TUint32* Ui = (TUint32*)(UiTemp->Ptr());
sl@0: 
sl@0: 	const TUint32* salt = (TUint32*)(aSalt.Ptr());
sl@0: 	TUint saltBytes = aSalt.Length();
sl@0: 
sl@0: 	for(TUint i = 1; i<=l; i++)
sl@0: 		{
sl@0: 		F(*hmac, Ti, S, Ui, hashBytes, salt, saltBytes, c, i);
sl@0: 		if(i == l)
sl@0: 			aKey.Append((TUint8*)Ti, r);
sl@0: 		else 
sl@0: 			aKey.Append((TUint8*)Ti, hashBytes);
sl@0: 		}
sl@0: 
sl@0: 	CleanupStack::PopAndDestroy(UiTemp);
sl@0: 	CleanupStack::PopAndDestroy(STemp);
sl@0: 	CleanupStack::PopAndDestroy(TiTemp);
sl@0: 	CleanupStack::PopAndDestroy(hmac);
sl@0: 	}
sl@0: 
sl@0: void TPKCS5KDF::F(CMessageDigest& aDigest, TUint32* aAccumulator, 
sl@0: 	TUint32* S, TUint32* Ui, TUint aHashBytes, const TUint32* aSalt, 
sl@0: 	TUint aSaltBytes, TUint c, TUint i)
sl@0: 	{
sl@0: 	TUint8 itmp[4];
sl@0: 	itmp[0] = (TUint8)((i >> 24) & 0xff);
sl@0: 	itmp[1] = (TUint8)((i >> 16) & 0xff);
sl@0: 	itmp[2] = (TUint8)((i >> 8) & 0xff);
sl@0: 	itmp[3] = (TUint8)(i & 0xff);
sl@0: 	TUint8* endOfS = Mem::Copy(S, aSalt, aSaltBytes);
sl@0: 	Mem::Copy((TUint32*)endOfS, (TUint32*)&itmp, 4);
sl@0: 
sl@0: 	TPtr8 sptr((TUint8*)S, aSaltBytes+4);
sl@0: 	sptr.SetLength(aSaltBytes+4);
sl@0: 	Mem::Copy(aAccumulator, (TUint32*)((aDigest.Final(sptr)).Ptr()),aHashBytes);
sl@0: 	Mem::Copy(Ui, aAccumulator, aHashBytes);
sl@0: 
sl@0: 	for(TUint j=1; j<c; j++)
sl@0: 		{
sl@0: 		TPtr8 uiptr((TUint8*)Ui, aHashBytes);
sl@0: 		uiptr.SetLength(aHashBytes);
sl@0: 		Mem::Copy(Ui, (TUint32*)((aDigest.Final(uiptr)).Ptr()), aHashBytes);
sl@0: 		XORString(Ui, aAccumulator, aHashBytes);
sl@0: 		}
sl@0: 	}
sl@0: 
sl@0: inline void TPKCS5KDF::XORString(const TUint32* aOp1, TUint32* aOp2,
sl@0: 	TUint aLength)
sl@0: 	{
sl@0: 	const TUint32* i = aOp1;
sl@0: 
sl@0: 	//this will overflow the whole final word if aLength % 4 != 0 
sl@0: 	//but I can't see this mattering cuz all memory allocation is on a word by word basis
sl@0: 	//i don't want to do this byte by byte as it'll be way slower
sl@0: 	//also, every sane digest is going to be a multiple of 4 -- so this isn't a problem
sl@0: 	for( ; aOp1 != (TUint32*)((TUint8*)i + aLength); )
sl@0: 		{
sl@0: 			*aOp2++ ^= *aOp1++;	
sl@0: 		}
sl@0: 	}
sl@0: