--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/crypto/weakcrypto/source/bigint/mont.cpp	Wed Jul 08 11:25:26 2009 +0100
@@ -0,0 +1,235 @@
+/*
+* Copyright (c) 2003-2009 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 <bigint.h>
+#include <euserext.h>
+#include "algorithms.h"
+#include "words.h"
+#include "windowslider.h"
+#include "mont.h"
+
+CMontgomeryStructure* CMontgomeryStructure::NewL(
+	const TInteger& aModulus)
+	{
+	CMontgomeryStructure* self = CMontgomeryStructure::NewLC(aModulus);
+	CleanupStack::Pop(self);
+	return self;
+	}
+
+CMontgomeryStructure* CMontgomeryStructure::NewLC(
+	const TInteger& aModulus)
+	{
+	CMontgomeryStructure* self = new(ELeave) CMontgomeryStructure;
+	CleanupStack::PushL(self);
+	self->ConstructL(aModulus);
+	return self;
+	}
+
+CMontgomeryStructure::~CMontgomeryStructure()
+	{
+	iModulus.Close();
+	iModulusInv.Close();
+	iWorkspace.Close();
+	iResult.Close();
+	}
+
+void CMontgomeryStructure::ConstructL(const TInteger& aModulus)
+	{
+	User::LeaveIfError(aModulus.IsOdd() ? KErrNone : KErrArgument);
+	
+	iModulusInv = RInteger::NewEmptyL(aModulus.Size());
+	iWorkspace = RInteger::NewEmptyL(5*aModulus.Size());
+	iModulus = RInteger::NewL(aModulus);
+	iResult = RInteger::NewEmptyL(aModulus.Size());
+	RecursiveInverseModPower2(iModulusInv.Ptr(), iWorkspace.Ptr(), 
+		iModulus.Ptr(), iModulus.Size());
+	}
+
+CMontgomeryStructure::CMontgomeryStructure()
+	{
+	}
+
+TInteger& CMontgomeryStructure::ConvertInL(TInteger& aInteger) const
+	{
+	aInteger <<= WordsToBits(iModulus.Size());
+	aInteger %= iModulus;
+	return aInteger;
+	}
+
+TInteger& CMontgomeryStructure::ConvertOutL(TInteger& aInteger) const
+	{
+	TUint* const T = iWorkspace.Ptr();
+	TUint* const R = aInteger.Ptr();
+	const TUint N = iModulus.Size();
+	User::LeaveIfError((aInteger.Size() <= N) ? KErrNone : KErrArgument);
+
+	CopyWords(T, aInteger.Ptr(), aInteger.Size());
+	SetWords(T + aInteger.Size(), 0, 2*N - aInteger.Size());
+	MontgomeryReduce(R, T+2*N, T, iModulus.Ptr(), iModulusInv.Ptr(), N);
+	return aInteger;
+	}
+
+const TInteger& CMontgomeryStructure::ReduceL(
+	const TInteger& aInteger) const
+	{
+	RInteger temp = RInteger::NewL(aInteger);
+	CleanupStack::PushL(temp);
+	ConvertInL(temp);
+	iResult.CopyL(ConvertOutL(temp), EFalse);
+	CleanupStack::PopAndDestroy(&temp);
+	return iResult;
+	}
+
+const TInteger& CMontgomeryStructure::MultiplyL(const TInteger& aA, 
+	const TInteger& aB) const
+	{
+	RInteger a = RInteger::NewL(aA);
+	CleanupStack::PushL(a);
+	RInteger b = RInteger::NewL(aB);
+	CleanupStack::PushL(b);
+	DoMultiplyL(iResult, ConvertInL(a), ConvertInL(b));
+	ConvertOutL(iResult);
+	CleanupStack::PopAndDestroy(&b); 
+	CleanupStack::PopAndDestroy(&a); 
+	return iResult;
+	}
+
+void CMontgomeryStructure::DoMultiplyL(TInteger& aResult, const TInteger& aA,
+	const TInteger& aB) const
+	{
+	User::LeaveIfError((aResult.Size() == iModulus.Size()) ? KErrNone : KErrArgument);
+					   
+	TUint* const T = iWorkspace.Ptr();
+	TUint* const R = aResult.Ptr();
+	const TUint N = iModulus.Size();
+	const TUint* const aReg = aA.Ptr();
+	const TUint* const bReg = aB.Ptr();
+	const TUint aSize = aA.Size();
+	const TUint bSize = aB.Size();
+	User::LeaveIfError((aSize <= N && bSize <= N) ? KErrNone : KErrArgument);
+
+	AsymmetricMultiply(T, T+2*N, aReg, aSize, bReg, bSize);
+	SetWords(T+aSize+bSize, 0, 2*N - aSize - bSize);
+	MontgomeryReduce(R, T+2*N, T, iModulus.Ptr(), iModulusInv.Ptr(), N);
+	}
+
+const TInteger& CMontgomeryStructure::SquareL(const TInteger& aA) const
+	{
+	RInteger a = RInteger::NewL(aA);
+	CleanupStack::PushL(a);
+	DoSquareL(iResult, ConvertInL(a));
+	ConvertOutL(iResult);
+	CleanupStack::PopAndDestroy(&a);
+	return iResult;
+	}
+
+void CMontgomeryStructure::DoSquareL(TInteger& aResult, const TInteger& aA) const
+	{
+	User::LeaveIfError((aResult.Size() == iModulus.Size()) ? KErrNone : KErrArgument);
+	TUint* const T = iWorkspace.Ptr();
+	TUint* const R = aResult.Ptr();
+	const TUint N = iModulus.Size();
+	const TUint* const aReg = aA.Ptr();
+	const TUint aSize = aA.Size();
+
+	User::LeaveIfError((aSize <= N) ? KErrNone : KErrArgument);
+
+	RecursiveSquare(T, T+2*N, aReg, aSize);
+	SetWords(T+2*aSize, 0, 2*N-2*aSize);
+	MontgomeryReduce(R, T+2*N, T, iModulus.Ptr(), iModulusInv.Ptr(), N);
+	}
+
+const TInteger& CMontgomeryStructure::ExponentiateL(
+	const TInteger& aBase, const TInteger& aExponent) const
+	{
+	//See HAC 14.85
+	if ((iResult.Size() != iModulus.Size()) ||
+		(aBase >= iModulus) ||
+		(!aBase.IsPositive()) ||
+		(!aExponent.IsPositive()))
+		{
+		User::Leave(KErrArgument);
+		}
+
+	// 1.1 Precomputation
+	// g1 <- g
+	// g2 <- g^2
+	RInteger g2 = RInteger::NewL(aBase);
+	CleanupStack::PushL(g2);
+	ConvertInL(g2);
+	//ConvertIn can shrink g2, because we call DoSquare on g2, g2 must be the same size as the modulus
+	g2.CleanGrowL(iModulus.Size());
+	RInteger g1 = RInteger::NewL(g2);
+	CleanupStack::PushL(g1);
+	DoSquareL(g2, g2);
+
+	TWindowSlider slider(aExponent);
+
+	// 1.2 
+	// For i from 1 to (2^(k-1) -1) do g2i+1 <- g2i-1 * g2
+	TUint count = (1 << (slider.WindowSize()-1)) - 1; //2^(k-1) -1
+	RRArray<RInteger> powerArray(count+1); //+1 because we append g1
+	User::LeaveIfError(powerArray.Append(g1));
+	CleanupStack::Pop(&g1); 
+	CleanupClosePushL(powerArray);
+	for(TUint k=1; k <= count; k++)
+		{
+		RInteger gi = RInteger::NewEmptyL(iModulus.Size());
+		DoMultiplyL(gi, g2, powerArray[k-1]);
+		User::LeaveIfError(powerArray.Append(gi));
+		}
+	
+	// 2 A <- 1, i <- t
+	RInteger temp = RInteger::NewL(TInteger::One());
+	CleanupStack::PushL(temp);
+	ConvertInL(temp);
+
+	RInteger& A = iResult;
+	//Set A to one converted in for this modulus without changing the memory size of A (iResult)
+	A.CopyL(temp, EFalse); 
+	CleanupStack::PopAndDestroy(&temp);
+
+	TInt i = aExponent.BitCount() - 1;
+
+	// 3 While i>=0 do:
+	while( i>=0 )
+		{
+		// 3.1 If ei == 0 then A <- A^2
+		if(!aExponent.Bit(i))
+			{
+			DoSquareL(A, A);
+			i--;
+			}
+		// 3.2 Find longest bitstring ei,ei-1,...,el s.t. i-l+1<=k and el==1
+		// and do:
+		// A <- (A^2^(i-l+1)) * g[the index indicated by the bitstring value]
+		else
+			{
+			slider.FindNextWindow(i);
+			assert(slider.Length() >= 1);
+			for(TUint j=0; j<slider.Length(); j++)
+				{
+				DoSquareL(A, A);
+				}
+			DoMultiplyL(A, A, powerArray[slider.Value()>>1]);
+			i -= slider.Length();
+			}
+		}
+	CleanupStack::PopAndDestroy(2, &g2); //powerArray, g2
+	return ConvertOutL(A); // A == iResult
+	}