/*

 * 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 <asymmetrickeys.h>

 #include <bigint.h>

 #include <random.h>

 #include <hash.h>

 #include "../common/inlines.h"

 #include "../bigint/mont.h"

 #include "dsakeypairshim.h"

 const TUint SHASIZE = 20;

 const TUint KMinPrimeLength = 512;

 const TUint KMaxPrimeLength = 1024;

 const TUint KPrimeLengthMultiple = 64;

 /* CDSAParameters */

 EXPORT_C const TInteger& CDSAParameters::P(void) const

 	{

 	return iP;

 	}

 EXPORT_C const TInteger& CDSAParameters::Q(void) const

 	{

 	return iQ;

 	}

 EXPORT_C const TInteger& CDSAParameters::G(void) const

 	{

 	return iG;

 	}

 EXPORT_C CDSAParameters::~CDSAParameters(void)

 	{

 	iP.Close();

 	iQ.Close();

 	iG.Close();

 	}

 EXPORT_C CDSAParameters* CDSAParameters::NewL(RInteger& aP, RInteger& aQ, 

 	RInteger& aG)

 	{

 	CDSAParameters* me = new (ELeave) CDSAParameters(aP, aQ, aG);

 	return (me);

 	}

 EXPORT_C TBool CDSAParameters::ValidatePrimesL(const CDSAPrimeCertificate& aCert)

 	const

 	{

 	TBool result = EFalse;

 	RInteger p;

 	RInteger q;

 	//Regenerate primes using aCert's seed and counter

 	TUint counter = aCert.Counter();

 	if(!CDSAParameters::GeneratePrimesL(aCert.Seed(), counter, p, 

 		P().BitCount(), q, ETrue))

 		{

 		return result;

 		}

 	//this doesn't leave, no need to push p and q

 	if(p == P() && q == Q() && counter == aCert.Counter())

 		{

 		result = ETrue;

 		}

 	p.Close();

 	q.Close();

 	return result;

 	}

 EXPORT_C TBool CDSAParameters::ValidPrimeLength(TUint aPrimeBits)

 	{

 	return (aPrimeBits >= KMinPrimeLength &&

 		aPrimeBits <= KMaxPrimeLength &&

 		aPrimeBits % KPrimeLengthMultiple == 0);

 	}

 EXPORT_C CDSAParameters::CDSAParameters(RInteger& aP, RInteger& aQ, 	

 	RInteger& aG) : iP(aP), iQ(aQ), iG(aG)

 	{

 	}

 EXPORT_C CDSAParameters::CDSAParameters(void)

 	{

 	}

 TBool CDSAParameters::GeneratePrimesL(const TDesC8& aSeed, TUint& aCounter, 

 	RInteger& aP, TUint aL, RInteger& aQ, TBool aUseInputCounter)

 	{

 	//This follows the steps in FIPS 186-2 

 	//See DSS Appendix 2.2

 	//Note. Step 1 is performed prior to calling GeneratePrimesL, so that this

 	//routine can be used for both generation and validation.

 	//Step 1.  Choose an arbitrary sequence of at least 160 bits and call it

 	//SEED.  Let g be the length of SEED in bits.

 	if(!CDSAParameters::ValidPrimeLength(aL))

 		{

 		User::Leave(KErrNotSupported);

 		}

 	CSHA1* sha1 = CSHA1::NewL();

 	CleanupStack::PushL(sha1);

 	HBufC8* seedBuf = aSeed.AllocLC();

 	TPtr8 seed = seedBuf->Des();

 	TUint gBytes = aSeed.Size();

 	//Note that the DSS's g = BytesToBits(gBytes) ie. the number of random bits

 	//in the seed.  

 	//This function has made the assumption (for ease of computation) that g%8

 	//is 0.  Ie the seed is a whole number of random bytes.

 	TBuf8<SHASIZE> U; 

 	TBuf8<SHASIZE> temp; 

 	const TUint n = (aL-1)/160;

 	const TUint b = (aL-1)%160;

 	HBufC8* Wbuf = HBufC8::NewMaxLC((n+1) * SHASIZE);

 	TUint8* W = const_cast<TUint8*>(Wbuf->Ptr());

 	U.Copy(sha1->Final(seed));

 	//Step 2. U = SHA-1[SEED] XOR SHA-1[(SEED+1) mod 2^g]

 	for(TInt i=gBytes - 1, carry=ETrue; i>=0 && carry; i--)

 		{

 		//!++(TUint) adds one to the current word which if it overflows to zero

 		//sets carry to 1 thus letting the loop continue.  It's a poor man's

 		//multi-word addition.  Swift eh?

 		carry = !++(seed[i]);

 		}

 	temp.Copy(sha1->Final(seed));

 	XorBuf(const_cast<TUint8*>(U.Ptr()), temp.Ptr(), SHASIZE);

 	//Step 3. Form q from U by setting the most significant bit (2^159)

 	//and the least significant bit to 1.

 	U[0] |= 0x80;

 	U[SHASIZE-1] |= 1;

 	aQ = RInteger::NewL(U);

 	CleanupStack::PushL(aQ);

 	//Step 4. Use a robust primality testing algo to test if q is prime

 	//The robust part is the calling codes problem.  This will use whatever

 	//random number generator you set for the thread.  To attempt FIPS 186-2

 	//compliance, set a FIPS 186-2 compliant RNG.

 	if( !aQ.IsPrimeL() )

 		{

 		//Step 5. If not exit and get a new seed

 		CleanupStack::PopAndDestroy(&aQ);

 		CleanupStack::PopAndDestroy(Wbuf);

 		CleanupStack::PopAndDestroy(seedBuf);

 		CleanupStack::PopAndDestroy(sha1);

 		return EFalse;

 		}

 	TUint counterEnd = aUseInputCounter ? aCounter+1 : 4096;

 	//Step 6. Let counter = 0 and offset = 2

 	//Note 1. that the DSS speaks of SEED + offset + k because they always

 	//refer to a constant SEED.  We update our seed as we go so the offset

 	//variable has already been added to seed in the previous iterations.

 	//Note 2. We've already added 1 to our seed, so the first time through this

 	//the offset in DSS speak will be 2.

 	for(TUint counter=0; counter < counterEnd; counter++)

 		{

 		//Step 7. For k=0, ..., n let

 		// Vk = SHA-1[(SEED + offset + k) mod 2^g]

 		//I'm storing the Vk's inside of a big W buffer.

 		for(TUint k=0; k<=n; k++)

 			{

 			for(TInt i=gBytes-1, carry=ETrue; i>=0 && carry; i--)

 				{

 				carry = !++(seed[i]);

 				}

 			if(!aUseInputCounter || counter == aCounter)

 				{

 				TPtr8 Wptr(W+(n-k)*SHASIZE, gBytes);

 				Wptr.Copy(sha1->Final(seed));

 				}

 			}

 		if(!aUseInputCounter || counter == aCounter)

 			{

 			//Step 8. Let W be the integer...  and let X = W + 2^(L-1)

 			const_cast<TUint8&>((*Wbuf)[SHASIZE - 1 - b/8]) |= 0x80;

 			TPtr8 Wptr(W + SHASIZE - 1 - b/8, aL/8, aL/8);

 			RInteger X = RInteger::NewL(Wptr);

 			CleanupStack::PushL(X);

 			//Step 9. Let c = X mod 2q and set p = X - (c-1)

 			RInteger twoQ = aQ.TimesL(TInteger::Two());

 			CleanupStack::PushL(twoQ);

 			RInteger c = X.ModuloL(twoQ);

 			CleanupStack::PushL(c);

 			--c;

 			aP = X.MinusL(c);

 			CleanupStack::PopAndDestroy(3, &X); //twoQ, c, X

 			CleanupStack::PushL(aP);

 			//Step 10 and 11: if p >= 2^(L-1) and p is prime

 			if( aP.Bit(aL-1) && aP.IsPrimeL() )

 				{

 				aCounter = counter;

 				CleanupStack::Pop(&aP);

 				CleanupStack::Pop(&aQ);

 				CleanupStack::PopAndDestroy(Wbuf);

 				CleanupStack::PopAndDestroy(seedBuf);

 				CleanupStack::PopAndDestroy(sha1);

 				return ETrue;

 				}

 			CleanupStack::PopAndDestroy(&aP);

 			}

 		}

 	CleanupStack::PopAndDestroy(&aQ);

 	CleanupStack::PopAndDestroy(Wbuf);

 	CleanupStack::PopAndDestroy(seedBuf);

 	CleanupStack::PopAndDestroy(sha1);

 	return EFalse;

 	}

 /* CDSAPublicKey */

 EXPORT_C CDSAPublicKey* CDSAPublicKey::NewL(RInteger& aP, RInteger& aQ, 

 	RInteger& aG, RInteger& aY)

 	{

 	CDSAPublicKey* self = new(ELeave) CDSAPublicKey(aP, aQ, aG, aY);

 	return self;

 	}

 EXPORT_C CDSAPublicKey* CDSAPublicKey::NewLC(RInteger& aP, RInteger& aQ, 

 	RInteger& aG, RInteger& aY)

 	{

 	CDSAPublicKey* self = NewL(aP, aQ, aG, aY);

 	CleanupStack::PushL(self);

 	return self;

 	}

 EXPORT_C const TInteger& CDSAPublicKey::Y(void) const

 	{

 	return iY;

 	}

 EXPORT_C CDSAPublicKey::CDSAPublicKey(void)

 	{

 	} 

 EXPORT_C CDSAPublicKey::CDSAPublicKey(RInteger& aP, RInteger& aQ, RInteger& aG, 

 	RInteger& aY) : CDSAParameters(aP, aQ, aG), iY(aY)

 	{

 	}

 EXPORT_C CDSAPublicKey::~CDSAPublicKey(void)

 	{

 	iY.Close();

 	}

 /* CDSAPrivateKey */

 EXPORT_C CDSAPrivateKey* CDSAPrivateKey::NewL(RInteger& aP, RInteger& aQ, 

 	RInteger& aG, RInteger& aX)

 	{

 	CDSAPrivateKey* self = new(ELeave) CDSAPrivateKey(aP, aQ, aG, aX);

 	return self;

 	}

 EXPORT_C CDSAPrivateKey* CDSAPrivateKey::NewLC(RInteger& aP, RInteger& aQ, 

 	RInteger& aG, RInteger& aX)

 	{

 	CDSAPrivateKey* self = NewL(aP, aQ, aG, aX);

 	CleanupStack::PushL(self);

 	return self;

 	}

 EXPORT_C const TInteger& CDSAPrivateKey::X(void) const

 	{

 	return iX;

 	}

 EXPORT_C CDSAPrivateKey::CDSAPrivateKey(RInteger& aP, RInteger& aQ, RInteger& aG, 

 	RInteger& aX) : CDSAParameters(aP, aQ, aG), iX(aX)

 	{

 	}

 EXPORT_C CDSAPrivateKey::~CDSAPrivateKey(void)

 	{

 	iX.Close();

 	}

 /* CDSAKeyPair */

 EXPORT_C CDSAKeyPair* CDSAKeyPair::NewL(TUint aKeyBits)

 	{

  	CDSAKeyPairShim* self = CDSAKeyPairShim::NewLC(aKeyBits);

  	CleanupStack::Pop();

  	return self;

 	}

 EXPORT_C CDSAKeyPair* CDSAKeyPair::NewLC(TUint aKeyBits)

 	{

  	CDSAKeyPairShim* self = CDSAKeyPairShim::NewLC(aKeyBits);

  	return self;

 	}

 EXPORT_C const CDSAPublicKey& CDSAKeyPair::PublicKey(void) const

 	{

 	return *iPublic;

 	}

 EXPORT_C const CDSAPrivateKey& CDSAKeyPair::PrivateKey(void) const

 	{

 	return *iPrivate;

 	}

 EXPORT_C CDSAKeyPair::~CDSAKeyPair(void) 

 	{

 	delete iPublic;

 	delete iPrivate;

 	delete iPrimeCertificate;

 	}

 EXPORT_C CDSAKeyPair::CDSAKeyPair(void) 

 	{

 	}

 EXPORT_C const CDSAPrimeCertificate& CDSAKeyPair::PrimeCertificate(void) const

 	{

 	return *iPrimeCertificate;

 	}

 /* CDSAPrimeCertificate */

 EXPORT_C CDSAPrimeCertificate* CDSAPrimeCertificate::NewL(const TDesC8& aSeed,

 	TUint aCounter)

 	{

 	CDSAPrimeCertificate* self = NewLC(aSeed, aCounter);

 	CleanupStack::Pop();

 	return self;

 	}

 EXPORT_C CDSAPrimeCertificate* CDSAPrimeCertificate::NewLC(const TDesC8& aSeed,

 	TUint aCounter)

 	{

 	CDSAPrimeCertificate* self = new(ELeave) CDSAPrimeCertificate(aCounter);

 	CleanupStack::PushL(self);

 	self->ConstructL(aSeed);

 	return self;

 	}

 EXPORT_C const TDesC8& CDSAPrimeCertificate::Seed(void) const

 	{

 	return *iSeed;

 	}

 EXPORT_C TUint CDSAPrimeCertificate::Counter(void) const

 	{

 	return iCounter;

 	}

 EXPORT_C CDSAPrimeCertificate::~CDSAPrimeCertificate(void) 

 	{

 	delete const_cast<HBufC8*>(iSeed);

 	}

 void CDSAPrimeCertificate::ConstructL(const TDesC8& aSeed)

 	{

 	iSeed = aSeed.AllocL();

 	}

 EXPORT_C CDSAPrimeCertificate::CDSAPrimeCertificate(TUint aCounter) 

 	: iCounter(aCounter)

 	{

 	}

 // Over taken by  shim version. so, exclude it from coverage.

 #ifdef _BullseyeCoverage

 #pragma suppress_warnings on

 #pragma BullseyeCoverage off

 #pragma suppress_warnings off

 #endif

 void CDSAKeyPair::ConstructL(TUint /*aPBits*/)

 	{

 	}

 // Unused exported and protected method can be excluded from coverage.

 EXPORT_C CDSAPrimeCertificate::CDSAPrimeCertificate(void) 

 	{

 	}

 EXPORT_C CDSAPrivateKey::CDSAPrivateKey(void)

 	{

 	}