private static DHDomainParameters DecodeDomainParameters(AlgorithmIdentifier algorithmIdentifier)
{
DerObjectIdentifier id = algorithmIdentifier.Algorithm;
Asn1Encodable parameters = algorithmIdentifier.Parameters;
if (parameters == null)
{
throw new ArgumentException("AlgorithmIdentifier parameters cannot be empty");
}
if (id.Equals(OiwObjectIdentifiers.ElGamalAlgorithm))
{
ElGamalParameter elg = ElGamalParameter.GetInstance(parameters);
return(new DHDomainParameters(elg.P, elg.G));
}
// we need the PKCS check to handle older keys marked with the X9 oid.
if (id.Equals(PkcsObjectIdentifiers.DhKeyAgreement) || KeyUtils.IsDHPkcsParam(parameters))
{
DHParameter dhParameters = DHParameter.GetInstance(parameters);
if (dhParameters.L != null)
{
return(new DHDomainParameters(dhParameters.P, null, dhParameters.G, dhParameters.L.IntValue));
}
else
{
return(new DHDomainParameters(dhParameters.P, dhParameters.G));
}
}
else if (id.Equals(X9ObjectIdentifiers.DHPublicNumber))
{
Asn1.X9.DHDomainParameters dhParameters = Asn1.X9.DHDomainParameters.GetInstance(parameters);
if (dhParameters.ValidationParms != null)
{
return(new DHDomainParameters(GetValue(dhParameters.P), GetValue(dhParameters.Q), GetValue(dhParameters.G), GetValue(dhParameters.J),
new DHValidationParameters(dhParameters.ValidationParms.Seed.GetBytes(), dhParameters.ValidationParms.PgenCounter.Value.IntValue)));
}
else
{
return(new DHDomainParameters(GetValue(dhParameters.P), GetValue(dhParameters.Q), GetValue(dhParameters.G), GetValue(dhParameters.J), null));
}
}
else
{
throw new ArgumentException("Unknown algorithm type: " + id);
}
}
