sl@0: /*
sl@0: * Copyright (c) 2007-2009 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: * DSA Keypair implementation
sl@0: * DSA keypair generation implementation
sl@0: *
sl@0: */
sl@0: 
sl@0: 
sl@0: /**
sl@0:  @file
sl@0: */
sl@0: 
sl@0: #include "dsakeypairgenimpl.h"
sl@0: #include "pluginconfig.h"
sl@0: #include "keypair.h"
sl@0: #include "common/inlines.h"    // For TClassSwap
sl@0: #include "mont.h"
sl@0: #include "sha1impl.h"
sl@0: #include <random.h>
sl@0: #include <securityerr.h>
sl@0: 
sl@0: 
sl@0: const TUint KShaSize = 20;
sl@0: const TUint KMinPrimeLength = 512;
sl@0: const TUint KMaxPrimeLength = 1024;
sl@0: const TUint KPrimeLengthMultiple = 64;
sl@0: 
sl@0: using namespace SoftwareCrypto;
sl@0: 
sl@0: 
sl@0: /* CDSAPrimeCertificate */
sl@0: 
sl@0: CDSAPrimeCertificate* CDSAPrimeCertificate::NewL(const TDesC8& aSeed, TUint aCounter)
sl@0: 	{
sl@0: 	CDSAPrimeCertificate* self = NewLC(aSeed, aCounter);
sl@0: 	CleanupStack::Pop();
sl@0: 	return self;
sl@0: 	}
sl@0: 
sl@0: CDSAPrimeCertificate* CDSAPrimeCertificate::NewLC(const TDesC8& aSeed, TUint aCounter)
sl@0: 	{
sl@0: 	CDSAPrimeCertificate* self = new(ELeave) CDSAPrimeCertificate(aCounter);
sl@0: 	CleanupStack::PushL(self);
sl@0: 	self->ConstructL(aSeed);
sl@0: 	return self;
sl@0: 	}
sl@0: 
sl@0: const TDesC8& CDSAPrimeCertificate::Seed() const
sl@0: 	{
sl@0: 	return *iSeed;
sl@0: 	}
sl@0: 
sl@0: TUint CDSAPrimeCertificate::Counter() const
sl@0: 	{
sl@0: 	return iCounter;
sl@0: 	}
sl@0: 
sl@0: CDSAPrimeCertificate::~CDSAPrimeCertificate() 
sl@0: 	{
sl@0: 	delete const_cast<HBufC8*>(iSeed);
sl@0: 	}
sl@0: 
sl@0: void CDSAPrimeCertificate::ConstructL(const TDesC8& aSeed)
sl@0: 	{
sl@0: 	iSeed = aSeed.AllocL();
sl@0: 	}
sl@0: 
sl@0: CDSAPrimeCertificate::CDSAPrimeCertificate(TUint aCounter) 
sl@0: 	: iCounter(aCounter)
sl@0: 	{
sl@0: 	}
sl@0: 
sl@0: CDSAPrimeCertificate::CDSAPrimeCertificate() 
sl@0: 	{
sl@0: 	}
sl@0: 
sl@0: 
sl@0: /* CDSAKeyPairGenImpl */
sl@0: CDSAKeyPairGenImpl::CDSAKeyPairGenImpl()
sl@0: 	{
sl@0: 	}
sl@0: 
sl@0: CDSAKeyPairGenImpl::~CDSAKeyPairGenImpl()
sl@0: 	{
sl@0: 	delete iPrimeCertificate;
sl@0: 	}
sl@0: 
sl@0: CDSAKeyPairGenImpl* CDSAKeyPairGenImpl::NewL()
sl@0: 	{
sl@0: 	CDSAKeyPairGenImpl* self = CDSAKeyPairGenImpl::NewLC();
sl@0: 	CleanupStack::Pop(self);
sl@0: 	return self;
sl@0: 	}
sl@0: 
sl@0: CDSAKeyPairGenImpl* CDSAKeyPairGenImpl::NewLC()
sl@0: 	{
sl@0: 	CDSAKeyPairGenImpl* self = new(ELeave) CDSAKeyPairGenImpl();
sl@0: 	CleanupStack::PushL(self);
sl@0: 	self->ConstructL();
sl@0: 	return self;
sl@0: 	}
sl@0: 
sl@0: void CDSAKeyPairGenImpl::ConstructL(void)
sl@0: 	{
sl@0: 	CKeyPairGenImpl::ConstructL();
sl@0: 	}
sl@0: 
sl@0: CExtendedCharacteristics* CDSAKeyPairGenImpl::CreateExtendedCharacteristicsL()
sl@0: 	{
sl@0: 	// All Symbian software plug-ins have unlimited concurrency, cannot be reserved
sl@0: 	// for exclusive use and are not CERTIFIED to be standards compliant.
sl@0: 	return CExtendedCharacteristics::NewL(KMaxTInt, EFalse);
sl@0: 	}
sl@0: 
sl@0: const CExtendedCharacteristics* CDSAKeyPairGenImpl::GetExtendedCharacteristicsL()
sl@0: 	{
sl@0: 	return CDSAKeyPairGenImpl::CreateExtendedCharacteristicsL();
sl@0: 	}
sl@0: 
sl@0: TUid CDSAKeyPairGenImpl::ImplementationUid() const
sl@0: 	{
sl@0: 	return KCryptoPluginDsaKeyPairGenUid;
sl@0: 	}
sl@0: 
sl@0: void CDSAKeyPairGenImpl::Reset()
sl@0: 	{
sl@0: 	// does nothing in this plugin
sl@0: 	}
sl@0: 
sl@0: TBool CDSAKeyPairGenImpl::ValidPrimeLength(TUint aPrimeBits)
sl@0: 	{
sl@0: 	return (aPrimeBits >= KMinPrimeLength &&
sl@0: 			aPrimeBits <= KMaxPrimeLength &&
sl@0: 			aPrimeBits % KPrimeLengthMultiple == 0);
sl@0: 	}
sl@0: 
sl@0: TBool CDSAKeyPairGenImpl::GeneratePrimesL(const TDesC8& aSeed,
sl@0: 										 TUint& aCounter, 
sl@0: 										 RInteger& aP, 
sl@0: 										 TUint aL, 
sl@0: 										 RInteger& aQ, 
sl@0: 										 TBool aUseInputCounter)
sl@0: 	{
sl@0: 	//This follows the steps in FIPS 186-2 
sl@0: 	//See DSS Appendix 2.2
sl@0: 	//Note. Step 1 is performed prior to calling GeneratePrimesL, so that this
sl@0: 	//routine can be used for both generation and validation.
sl@0: 	//Step 1.  Choose an arbitrary sequence of at least 160 bits and call it
sl@0: 	//SEED.  Let g be the length of SEED in bits.
sl@0: 
sl@0: 	if(!ValidPrimeLength(aL))
sl@0: 		{
sl@0: 		User::Leave(KErrNotSupported);
sl@0: 		}
sl@0: 	
sl@0: 	CSHA1Impl* sha1 = CSHA1Impl::NewL();
sl@0: 	CleanupStack::PushL(sha1);
sl@0: 
sl@0: 	HBufC8* seedBuf = aSeed.AllocLC();
sl@0: 	TPtr8 seed = seedBuf->Des();
sl@0: 	TUint gBytes = aSeed.Size();
sl@0: 	
sl@0: 	//Note that the DSS's g = BytesToBits(gBytes) ie. the number of random bits
sl@0: 	//in the seed.  
sl@0: 	//This function has made the assumption (for ease of computation) that g%8
sl@0: 	//is 0.  Ie the seed is a whole number of random bytes.
sl@0: 	TBuf8<KShaSize> U; 
sl@0: 	TBuf8<KShaSize> temp; 
sl@0: 	const TUint n = (aL-1)/160;
sl@0: 	const TUint b = (aL-1)%160;
sl@0: 	HBufC8* Wbuf = HBufC8::NewMaxLC((n+1) * KShaSize);
sl@0: 	TUint8* W = const_cast<TUint8*>(Wbuf->Ptr());
sl@0: 
sl@0: 	U.Copy(sha1->Final(seed));
sl@0: 	
sl@0: 	//Step 2. U = SHA-1[SEED] XOR SHA-1[(SEED+1) mod 2^g]
sl@0: 	for(TInt i=gBytes - 1, carry=ETrue; i>=0 && carry; i--)
sl@0: 		{
sl@0: 		//!++(TUint) adds one to the current word which if it overflows to zero
sl@0: 		//sets carry to 1 thus letting the loop continue.  It's a poor man's
sl@0: 		//multi-word addition.  Swift eh?
sl@0: 		carry = !++(seed[i]);
sl@0: 		}
sl@0: 
sl@0: 	temp.Copy(sha1->Final(seed));
sl@0: 	XorBuf(const_cast<TUint8*>(U.Ptr()), temp.Ptr(), KShaSize);
sl@0: 
sl@0: 	//Step 3. Form q from U by setting the most significant bit (2^159)
sl@0: 	//and the least significant bit to 1.
sl@0: 	U[0] |= 0x80;
sl@0: 	U[KShaSize-1] |= 1;
sl@0: 
sl@0: 	aQ = RInteger::NewL(U);
sl@0: 	CleanupStack::PushL(aQ);
sl@0: 
sl@0: 	//Step 4. Use a robust primality testing algo to test if q is prime
sl@0: 	//The robust part is the calling codes problem.  This will use whatever
sl@0: 	//random number generator you set for the thread.  To attempt FIPS 186-2
sl@0: 	//compliance, set a FIPS 186-2 compliant RNG.
sl@0: 	if( !aQ.IsPrimeL() )
sl@0: 		{
sl@0: 		//Step 5. If not exit and get a new seed
sl@0: 		CleanupStack::PopAndDestroy(4, sha1);
sl@0: 		return EFalse;
sl@0: 		}
sl@0: 	
sl@0: 	TUint counterEnd = aUseInputCounter ? aCounter+1 : 4096;
sl@0: 	
sl@0: 	//Step 6. Let counter = 0 and offset = 2
sl@0: 	//Note 1. that the DSS speaks of SEED + offset + k because they always
sl@0: 	//refer to a constant SEED.  We update our seed as we go so the offset
sl@0: 	//variable has already been added to seed in the previous iterations.
sl@0: 	//Note 2. We've already added 1 to our seed, so the first time through this
sl@0: 	//the offset in DSS speak will be 2.
sl@0: 	for(TUint counter=0; counter < counterEnd; counter++)
sl@0: 		{
sl@0: 		//Step 7. For k=0, ..., n let
sl@0: 		// Vk = SHA-1[(SEED + offset + k) mod 2^g]
sl@0: 		//I'm storing the Vk's inside of a big W buffer.
sl@0: 		for(TUint k=0; k<=n; k++)
sl@0: 			{
sl@0: 			for(TInt i=gBytes-1, carry=ETrue; i>=0 && carry; i--)
sl@0: 				{
sl@0: 				carry = !++(seed[i]);
sl@0: 				}
sl@0: 			if(!aUseInputCounter || counter == aCounter)
sl@0: 				{
sl@0: 				TPtr8 Wptr(W+(n-k)*KShaSize, gBytes);
sl@0: 				Wptr.Copy(sha1->Final(seed));
sl@0: 				}
sl@0: 			}
sl@0: 		if(!aUseInputCounter || counter == aCounter)
sl@0: 			{
sl@0: 			//Step 8. Let W be the integer...  and let X = W + 2^(L-1)
sl@0: 			const_cast<TUint8&>((*Wbuf)[KShaSize - 1 - b/8]) |= 0x80;
sl@0: 			TPtr8 Wptr(W + KShaSize - 1 - b/8, aL/8, aL/8);
sl@0: 			RInteger X = RInteger::NewL(Wptr);
sl@0: 			CleanupStack::PushL(X);
sl@0: 			//Step 9. Let c = X mod 2q and set p = X - (c-1)
sl@0: 			RInteger twoQ = aQ.TimesL(TInteger::Two());
sl@0: 			CleanupStack::PushL(twoQ);
sl@0: 			RInteger c = X.ModuloL(twoQ);
sl@0: 			CleanupStack::PushL(c);
sl@0: 			--c;
sl@0: 			aP = X.MinusL(c);
sl@0: 			CleanupStack::PopAndDestroy(3, &X); //twoQ, c, X
sl@0: 			CleanupStack::PushL(aP);
sl@0: 			
sl@0: 			//Step 10 and 11: if p >= 2^(L-1) and p is prime
sl@0: 			if( aP.Bit(aL-1) && aP.IsPrimeL() )
sl@0: 				{
sl@0: 				aCounter = counter;
sl@0: 				CleanupStack::Pop(2, &aQ);
sl@0: 				CleanupStack::PopAndDestroy(3, sha1);
sl@0: 				return ETrue;
sl@0: 				}
sl@0: 			CleanupStack::PopAndDestroy(&aP);
sl@0: 			}
sl@0: 		}
sl@0: 	CleanupStack::PopAndDestroy(4, &sha1);
sl@0: 	return EFalse;
sl@0: 	}
sl@0: 
sl@0: void CDSAKeyPairGenImpl::GenerateKeyPairL(TInt aKeySize, 
sl@0: 										const CCryptoParams& aKeyParameters,
sl@0: 										CKeyPair*& aKeyPair)
sl@0: 	{
sl@0: 	//This is the first step of DSA prime generation.  The remaining steps are
sl@0: 	//performed in CDSAParameters::GeneratePrimesL
sl@0: 	//Step 1.  Choose an arbitrary sequence of at least 160 bits and call it
sl@0: 	//SEED.  Let g be the length of SEED in bits.	
sl@0: 	TBuf8<KShaSize> seed(KShaSize);
sl@0: 	TUint c;
sl@0: 	RInteger p;
sl@0: 	RInteger q;
sl@0: 	
sl@0: 	do 
sl@0: 		{
sl@0: 	    TRAPD(err, GenerateRandomBytesL(seed));
sl@0: 	    if((err != KErrNone) && (err != KErrNotSecure))
sl@0: 	        User::Leave(err);
sl@0: 		}
sl@0: 	while(!GeneratePrimesL(seed, c, p, aKeySize, q));
sl@0: 	
sl@0: 	//Double PushL will not fail as GeneratePrimesL uses the CleanupStack
sl@0: 	//(at least one push and pop ;)
sl@0: 	CleanupStack::PushL(p);
sl@0: 	CleanupStack::PushL(q);
sl@0: 
sl@0: 	iPrimeCertificate = CDSAPrimeCertificate::NewL(seed, c);
sl@0: 	
sl@0: 	// aKeyParameters isn't const here anymore
sl@0: 	CCryptoParams& paramRef=const_cast<CCryptoParams&>(aKeyParameters);
sl@0: 	paramRef.AddL(c, KDsaKeyGenerationCounterUid);
sl@0: 	paramRef.AddL(seed, KDsaKeyGenerationSeedUid);
sl@0: 	
sl@0: 	CMontgomeryStructure* montP = CMontgomeryStructure::NewLC(p);
sl@0: 	
sl@0: 	--p;
sl@0: 
sl@0: 	// e = (p-1)/q
sl@0: 	RInteger e = p.DividedByL(q);
sl@0: 	CleanupStack::PushL(e);
sl@0: 
sl@0: 	--p; //now it's p-2 :)
sl@0: 
sl@0: 	RInteger h;
sl@0: 	const TInteger* g = 0;
sl@0: 	do
sl@0: 		{
sl@0: 		// find a random h | 1 < h < p-1
sl@0: 		h = RInteger::NewRandomL(TInteger::Two(), p);
sl@0: 		CleanupStack::PushL(h);
sl@0: 		// g = h^e mod p
sl@0: 		g = &(montP->ExponentiateL(h, e));
sl@0: 		CleanupStack::PopAndDestroy(&h); 
sl@0: 		}
sl@0: 	while( *g <= TInteger::One() );
sl@0: 	CleanupStack::PopAndDestroy(&e);
sl@0: 
sl@0: 	++p; //reincrement p to original value
sl@0: 	++p;
sl@0: 
sl@0: 
sl@0: 	RInteger g1 = RInteger::NewL(*g); //take a copy of montP's g
sl@0: 	CleanupStack::PushL(g1);
sl@0: 	--q;
sl@0: 	// select random x | 0 < x < q
sl@0: 	RInteger x = RInteger::NewRandomL(TInteger::One(), q);
sl@0: 	CleanupStack::PushL(x);
sl@0: 	++q;
sl@0: 
sl@0: 	//
sl@0: 	// create the keys parameters
sl@0: 	CCryptoParams* privateKeyParameters = CCryptoParams::NewLC();
sl@0: 	privateKeyParameters->AddL(p, KDsaKeyParameterPUid);
sl@0: 	privateKeyParameters->AddL(q, KDsaKeyParameterQUid);
sl@0: 	privateKeyParameters->AddL(g1, KDsaKeyParameterGUid);
sl@0: 	privateKeyParameters->AddL(x, KDsaKeyParameterXUid);
sl@0: 	TKeyProperty privateKeyProperties = {KDSAKeyPairGeneratorUid, 
sl@0: 										 KCryptoPluginDsaKeyPairGenUid,
sl@0: 									     KDsaPrivateKeyUid, 
sl@0: 									     KNonEmbeddedKeyUid};
sl@0: 
sl@0: 	CCryptoParams* publicKeyParameters = CCryptoParams::NewLC();
sl@0: 	publicKeyParameters->AddL(p, KDsaKeyParameterPUid);
sl@0: 	publicKeyParameters->AddL(q, KDsaKeyParameterQUid);
sl@0: 	publicKeyParameters->AddL(g1, KDsaKeyParameterGUid);
sl@0: 	RInteger y = RInteger::NewL(montP->ExponentiateL(*g, x));
sl@0: 	CleanupStack::PushL(y);
sl@0: 	publicKeyParameters->AddL(y, KDsaKeyParameterYUid);
sl@0: 	TKeyProperty publicKeyProperties = {KDSAKeyPairGeneratorUid,
sl@0: 										KCryptoPluginDsaKeyPairGenUid, 
sl@0: 										KDsaPublicKeyUid,
sl@0: 										KNonEmbeddedKeyUid};
sl@0: 
sl@0: 	//
sl@0: 	// create the private key
sl@0: 	//
sl@0: 	CKey* privateKey = CKey::NewL(privateKeyProperties, *privateKeyParameters);
sl@0: 	CleanupStack::PushL(privateKey);
sl@0: 
sl@0: 	//
sl@0: 	// create the public key
sl@0: 	//
sl@0: 	CKey* publicKey = CKey::NewL(publicKeyProperties, *publicKeyParameters);
sl@0: 	CleanupStack::PushL(publicKey);
sl@0: 
sl@0: 	aKeyPair = CKeyPair::NewL(publicKey, privateKey);
sl@0: 
sl@0: 	//publicKey, publicKeyParameters, y, privateKey, privateKeyParameters, x, g1, montP, q, p
sl@0: 	CleanupStack::Pop(2, privateKey);
sl@0: 	CleanupStack::PopAndDestroy(8, &p);	
sl@0: 	}