public DHPrivateKeyParameters(
BigInteger x,
DHParameters parameters)
: base(true, parameters)
{
this.x = x;
}
public DHPrivateKeyParameters(
BigInteger x,
DHParameters parameters,
DerObjectIdentifier algorithmOid)
: base(true, parameters, algorithmOid)
{
this.x = x;
}
protected DHKeyParameters(
bool isPrivate,
DHParameters parameters,
DerObjectIdentifier algorithmOid)
: base(isPrivate)
{
// TODO Should we allow parameters to be null?
this.parameters = parameters;
this.algorithmOid = algorithmOid;
}
public DHPublicKeyParameters(
BigInteger y,
DHParameters parameters)
: base(false, parameters)
{
if (y == null)
throw new ArgumentNullException("y");
this.y = y;
}
public DHPublicKeyParameters(
BigInteger y,
DHParameters parameters,
DerObjectIdentifier algorithmOid)
: base(false, parameters, algorithmOid)
{
if (y == null)
throw new ArgumentNullException("y");
this.y = y;
}
public AsymmetricCipherKeyPair GenerateKeyPair()
{
DHKeyGeneratorHelper helper = DHKeyGeneratorHelper.Instance;
ElGamalParameters egp = param.Parameters;
DHParameters dhp = new DHParameters(egp.P, egp.G, null, 0, egp.L);
BigInteger x = helper.CalculatePrivate(dhp, param.Random);
BigInteger y = helper.CalculatePublic(dhp, x);
return new AsymmetricCipherKeyPair(
new ElGamalPublicKeyParameters(y, egp),
new ElGamalPrivateKeyParameters(x, egp));
}
public virtual void Init(
ICipherParameters parameters)
{
if (parameters is ParametersWithRandom)
{
parameters = ((ParametersWithRandom) parameters).Parameters;
}
if (!(parameters is DHPrivateKeyParameters))
{
throw new ArgumentException("DHEngine expects DHPrivateKeyParameters");
}
this.key = (DHPrivateKeyParameters) parameters;
this.dhParams = key.Parameters;
}
internal BigInteger CalculatePrivate(
DHParameters dhParams,
SecureRandom random)
{
int limit = dhParams.L;
if (limit != 0)
{
int minWeight = limit >> 2;
for (;;)
{
BigInteger x = new BigInteger(limit, random).SetBit(limit - 1);
if (WNafUtilities.GetNafWeight(x) >= minWeight)
{
return x;
}
}
}
BigInteger min = BigInteger.Two;
int m = dhParams.M;
if (m != 0)
{
min = BigInteger.One.ShiftLeft(m - 1);
}
BigInteger q = dhParams.Q;
if (q == null)
{
q = dhParams.P;
}
BigInteger max = q.Subtract(BigInteger.Two);
{
int minWeight = max.BitLength >> 2;
for (;;)
{
BigInteger x = BigIntegers.CreateRandomInRange(min, max, random);
if (WNafUtilities.GetNafWeight(x) >= minWeight)
{
return x;
}
}
}
}
private static DHPublicKeyParameters ReadPkcsDHParam(DerObjectIdentifier algOid,
BigInteger y, Asn1Sequence seq)
{
DHParameter para = new DHParameter(seq);
BigInteger lVal = para.L;
int l = lVal == null ? 0 : lVal.IntValue;
DHParameters dhParams = new DHParameters(para.P, para.G, null, l);
return new DHPublicKeyParameters(y, dhParams, algOid);
}
internal BigInteger CalculatePublic(
DHParameters dhParams,
BigInteger x)
{
return dhParams.G.ModPow(x, dhParams.P);
}
protected bool Equals(
DHParameters other)
{
return p.Equals(other.p)
&& g.Equals(other.g)
&& Platform.Equals(q, other.q);
}
public void Init(
ICipherParameters parameters)
{
AsymmetricKeyParameter kParam;
if (parameters is ParametersWithRandom)
{
ParametersWithRandom rParam = (ParametersWithRandom)parameters;
this.random = rParam.Random;
kParam = (AsymmetricKeyParameter)rParam.Parameters;
}
else
{
this.random = new SecureRandom();
kParam = (AsymmetricKeyParameter)parameters;
}
if (!(kParam is DHPrivateKeyParameters))
{
throw new ArgumentException("DHEngine expects DHPrivateKeyParameters");
}
this.key = (DHPrivateKeyParameters)kParam;
this.dhParams = key.Parameters;
}
protected DHKeyParameters(
bool isPrivate,
DHParameters parameters)
: this(isPrivate, parameters, PkcsObjectIdentifiers.DhKeyAgreement)
{
}
