crypto/weakcryptospi/source/pkcs5kdf/pkcs5kdf.cpp
changeset 19 cd501b96611d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/crypto/weakcryptospi/source/pkcs5kdf/pkcs5kdf.cpp	Fri Nov 06 13:21:00 2009 +0200
@@ -0,0 +1,115 @@
+/*
+* 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: 
+*
+*/
+
+
+/**
+ @file
+*/
+
+#include "pkcs5kdf.h"
+
+/* Before complaining about the variable names in this file, 
+ * read the pkcs5 spec and all will become clear.
+ */
+
+EXPORT_C void TPKCS5KDF::DeriveKeyL(TDes8& aKey, const TDesC8& aPasswd, const TDesC8& aSalt, 
+	const TUint aIterations)
+{
+	CSHA1* sha1 = CSHA1::NewL();
+	CleanupStack::PushL(sha1);
+	CHMAC* hmac = CHMAC::NewL(aPasswd, sha1);
+	CleanupStack::Pop(sha1); //hmac now owns it
+	CleanupStack::PushL(hmac);
+
+	TUint hashBytes = hmac->HashSize();
+	TUint c = aIterations;
+	TUint l = aKey.Length() / hashBytes; 
+	if(aKey.Length() % hashBytes != 0) //round up if mod !=0
+		{
+		l+=1;
+		}
+	TUint r = aKey.Length() - (l-1) * hashBytes; //r == length of last block
+	
+	HBufC8* TiTemp = HBufC8::NewLC(hashBytes);
+	TUint32* Ti = (TUint32*)(TiTemp->Ptr());
+	aKey.SetLength(0); //we've already saved the length we want
+
+	HBufC8* STemp = HBufC8::NewLC(aSalt.Length() + sizeof(TUint32));
+	TUint32* S = (TUint32*)(STemp->Ptr());
+
+	HBufC8* UiTemp = HBufC8::NewLC(hashBytes);
+	TUint32* Ui = (TUint32*)(UiTemp->Ptr());
+
+	const TUint32* salt = (TUint32*)(aSalt.Ptr());
+	TUint saltBytes = aSalt.Length();
+
+	for(TUint i = 1; i<=l; i++)
+		{
+		F(*hmac, Ti, S, Ui, hashBytes, salt, saltBytes, c, i);
+		if(i == l)
+			aKey.Append((TUint8*)Ti, r);
+		else 
+			aKey.Append((TUint8*)Ti, hashBytes);
+		}
+
+	CleanupStack::PopAndDestroy(UiTemp);
+	CleanupStack::PopAndDestroy(STemp);
+	CleanupStack::PopAndDestroy(TiTemp);
+	CleanupStack::PopAndDestroy(hmac);
+	}
+
+void TPKCS5KDF::F(CMessageDigest& aDigest, TUint32* aAccumulator, 
+	TUint32* S, TUint32* Ui, TUint aHashBytes, const TUint32* aSalt, 
+	TUint aSaltBytes, TUint c, TUint i)
+	{
+	TUint8 itmp[4];
+	itmp[0] = (TUint8)((i >> 24) & 0xff);
+	itmp[1] = (TUint8)((i >> 16) & 0xff);
+	itmp[2] = (TUint8)((i >> 8) & 0xff);
+	itmp[3] = (TUint8)(i & 0xff);
+	TUint8* endOfS = Mem::Copy(S, aSalt, aSaltBytes);
+	Mem::Copy((TUint32*)endOfS, (TUint32*)&itmp, 4);
+
+	TPtr8 sptr((TUint8*)S, aSaltBytes+4);
+	sptr.SetLength(aSaltBytes+4);
+	Mem::Copy(aAccumulator, (TUint32*)((aDigest.Final(sptr)).Ptr()),aHashBytes);
+	Mem::Copy(Ui, aAccumulator, aHashBytes);
+
+	for(TUint j=1; j<c; j++)
+		{
+		TPtr8 uiptr((TUint8*)Ui, aHashBytes);
+		uiptr.SetLength(aHashBytes);
+		Mem::Copy(Ui, (TUint32*)((aDigest.Final(uiptr)).Ptr()), aHashBytes);
+		XORString(Ui, aAccumulator, aHashBytes);
+		}
+	}
+
+inline void TPKCS5KDF::XORString(const TUint32* aOp1, TUint32* aOp2,
+	TUint aLength)
+	{
+	const TUint32* i = aOp1;
+
+	//this will overflow the whole final word if aLength % 4 != 0 
+	//but I can't see this mattering cuz all memory allocation is on a word by word basis
+	//i don't want to do this byte by byte as it'll be way slower
+	//also, every sane digest is going to be a multiple of 4 -- so this isn't a problem
+	for( ; aOp1 != (TUint32*)((TUint8*)i + aLength); )
+		{
+			*aOp2++ ^= *aOp1++;	
+		}
+	}
+