1 /*

     2 * Copyright (c) 2003-2009 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of the License "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description: 

    15 *

    16 */

    17 

    18 

    19 #include <asymmetric.h>

    20 

    21 EXPORT_C CDSASigner* CDSASigner::NewL(const CDSAPrivateKey& aKey)

    22 	{

    23 	CDSASigner* self = new(ELeave) CDSASigner(aKey);

    24 	return self;

    25 	}

    26 

    27 EXPORT_C CDSASigner* CDSASigner::NewLC(const CDSAPrivateKey& aKey) 

    28 	{

    29 	CDSASigner* self = NewL(aKey); 

    30 	CleanupStack::PushL(self);

    31 	return self;

    32 	}

    33 

    34 TInt CDSASigner::MaxInputLength(void) const

    35 	{

    36 	return SHA1_HASH;  // from hash.h

    37 	}

    38 

    39 CDSASignature* CDSASigner::SignL(const TDesC8& aInput) const

    40 	{

    41 	//see HAC 11.56 or DSS section 5

    42 	//I'll follow HAC as I like its description better

    43 	//We don't check that r and s are non both non-null like the DSS

    44 	//states you _optionally_ can.  The chances of this are _incredibly_ small.

    45 	//You've got a much better chance of a bit failure ocurring in the hardware

    46 	//than this.

    47 

    48 	// a) Select a random secret integer (k | 0 < k < q)

    49 	RInteger qminus1 = RInteger::NewL(iPrivateKey.Q());

    50 	CleanupStack::PushL(qminus1);

    51 	--qminus1;

    52 	RInteger k = RInteger::NewRandomL(TInteger::One(), qminus1);

    53 	CleanupStack::PopAndDestroy(&qminus1);

    54 	CleanupStack::PushL(k);

    55 

    56 	// b) compute r = (g^k mod p) mod q

    57 	RInteger r = TInteger::ModularExponentiateL(iPrivateKey.G(), k, 	

    58 		iPrivateKey.P());

    59 	CleanupStack::PushL(r);

    60 	r %= iPrivateKey.Q();

    61 

    62 	// c) compute k^(-1) mod q 

    63 	RInteger kinv = k.InverseModL(iPrivateKey.Q());

    64 	CleanupStack::PushL(kinv);

    65 

    66 	// d) compute s = k^(-1) * {h(m) + xr} mod q

    67 	// Note that in order to be interoperable, compliant with the DSS, and

    68 	// secure, aInput must be the result of a SHA-1 hash

    69 	RInteger hm = RInteger::NewL(aInput);

    70 	CleanupStack::PushL(hm);

    71 	

    72 	RInteger s = iPrivateKey.X().TimesL(r);

    73 	CleanupStack::PushL(s);

    74 	s += hm;

    75 	s *= kinv;

    76 	s %= iPrivateKey.Q();

    77 

    78 	// e) signature for m is the pair (r,s)

    79 	CDSASignature* signature = CDSASignature::NewL(r, s);//transfers ownership

    80 	CleanupStack::Pop(&s);

    81 	CleanupStack::PopAndDestroy(&hm);

    82 	CleanupStack::PopAndDestroy(&kinv);

    83 	CleanupStack::Pop(&r);

    84 	CleanupStack::PopAndDestroy(&k);	

    85 	return signature;

    86 	}

    87 

    88 CDSASigner::CDSASigner(const CDSAPrivateKey& aKey) 

    89 	: iPrivateKey(aKey)

    90 	{

    91 	}

    92