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using System;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Sec;
using Org.BouncyCastle.Asn1.X9;
using Org.BouncyCastle.Crypto.EC;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Math.EC;
using Org.BouncyCastle.Math.EC.Multiplier;
using Org.BouncyCastle.Security;
namespace Org.BouncyCastle.Crypto.Generators
{
public class ECKeyPairGenerator
: IAsymmetricCipherKeyPairGenerator
{
private readonly string algorithm;
private ECDomainParameters parameters;
private DerObjectIdentifier publicKeyParamSet;
private SecureRandom random;
public ECKeyPairGenerator()
: this("EC")
{
}
public ECKeyPairGenerator(
string algorithm)
{
if (algorithm == null)
throw new ArgumentNullException("algorithm");
this.algorithm = ECKeyParameters.VerifyAlgorithmName(algorithm);
}
public void Init(
KeyGenerationParameters parameters)
{
if (parameters is ECKeyGenerationParameters)
{
ECKeyGenerationParameters ecP = (ECKeyGenerationParameters) parameters;
this.publicKeyParamSet = ecP.PublicKeyParamSet;
this.parameters = ecP.DomainParameters;
}
else
{
DerObjectIdentifier oid;
switch (parameters.Strength)
{
case 192:
oid = X9ObjectIdentifiers.Prime192v1;
break;
case 224:
oid = SecObjectIdentifiers.SecP224r1;
break;
case 239:
oid = X9ObjectIdentifiers.Prime239v1;
break;
case 256:
oid = X9ObjectIdentifiers.Prime256v1;
break;
case 384:
oid = SecObjectIdentifiers.SecP384r1;
break;
case 521:
oid = SecObjectIdentifiers.SecP521r1;
break;
default:
throw new InvalidParameterException("unknown key size.");
}
X9ECParameters ecps = FindECCurveByOid(oid);
this.publicKeyParamSet = oid;
this.parameters = new ECDomainParameters(
ecps.Curve, ecps.G, ecps.N, ecps.H, ecps.GetSeed());
}
this.random = parameters.Random;
if (this.random == null)
{
this.random = CryptoServicesRegistrar.GetSecureRandom();
}
}
/**
* Given the domain parameters this routine generates an EC key
* pair in accordance with X9.62 section 5.2.1 pages 26, 27.
*/
public AsymmetricCipherKeyPair GenerateKeyPair()
{
BigInteger n = parameters.N;
BigInteger d;
int minWeight = n.BitLength >> 2;
for (;;)
{
d = new BigInteger(n.BitLength, random);
if (d.CompareTo(BigInteger.One) < 0 || d.CompareTo(n) >= 0)
continue;
if (WNafUtilities.GetNafWeight(d) < minWeight)
continue;
break;
}
ECPoint q = CreateBasePointMultiplier().Multiply(parameters.G, d);
if (publicKeyParamSet != null)
{
return new AsymmetricCipherKeyPair(
new ECPublicKeyParameters(algorithm, q, publicKeyParamSet),
new ECPrivateKeyParameters(algorithm, d, publicKeyParamSet));
}
return new AsymmetricCipherKeyPair(
new ECPublicKeyParameters(algorithm, q, parameters),
new ECPrivateKeyParameters(algorithm, d, parameters));
}
protected virtual ECMultiplier CreateBasePointMultiplier()
{
return new FixedPointCombMultiplier();
}
internal static X9ECParameters FindECCurveByName(string name)
{
X9ECParameters ecP = CustomNamedCurves.GetByName(name);
if (ecP == null)
{
ecP = ECNamedCurveTable.GetByName(name);
}
return ecP;
}
internal static X9ECParametersHolder FindECCurveByNameLazy(string name)
{
X9ECParametersHolder holder = CustomNamedCurves.GetByNameLazy(name);
if (holder == null)
{
holder = ECNamedCurveTable.GetByNameLazy(name);
}
return holder;
}
internal static X9ECParameters FindECCurveByOid(DerObjectIdentifier oid)
{
X9ECParameters ecP = CustomNamedCurves.GetByOid(oid);
if (ecP == null)
{
ecP = ECNamedCurveTable.GetByOid(oid);
}
return ecP;
}
internal static X9ECParametersHolder FindECCurveByOidLazy(DerObjectIdentifier oid)
{
X9ECParametersHolder holder = CustomNamedCurves.GetByOidLazy(oid);
if (holder == null)
{
holder = ECNamedCurveTable.GetByOidLazy(oid);
}
return holder;
}
internal static ECPublicKeyParameters GetCorrespondingPublicKey(
ECPrivateKeyParameters privKey)
{
ECDomainParameters ec = privKey.Parameters;
ECPoint q = new FixedPointCombMultiplier().Multiply(ec.G, privKey.D);
if (privKey.PublicKeyParamSet != null)
{
return new ECPublicKeyParameters(privKey.AlgorithmName, q, privKey.PublicKeyParamSet);
}
return new ECPublicKeyParameters(privKey.AlgorithmName, q, ec);
}
}
}
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