/// <summary>
/// Get a handle to the secret agreement generated between two parties
/// </summary>
public SafeNCryptSecretHandle DeriveSecretAgreementHandle(ECDiffieHellmanPublicKey otherPartyPublicKey)
{
ArgumentNullException.ThrowIfNull(otherPartyPublicKey);
if (otherPartyPublicKey is ECDiffieHellmanCngPublicKey otherKey)
{
using (CngKey importedKey = otherKey.Import())
{
return(DeriveSecretAgreementHandle(importedKey));
}
}
ECParameters otherPartyParameters = otherPartyPublicKey.ExportParameters();
using (ECDiffieHellmanCng otherPartyCng = new ECDiffieHellmanCng())
{
otherPartyCng.ImportParameters(otherPartyParameters);
using (otherKey = (ECDiffieHellmanCngPublicKey)otherPartyCng.PublicKey)
using (CngKey importedKey = otherKey.Import())
{
return(DeriveSecretAgreementHandle(importedKey));
}
}
}
public override byte[] DeriveKeyMaterial(ECDiffieHellmanPublicKey otherPartyPublicKey)
{
ArgumentNullException.ThrowIfNull(otherPartyPublicKey);
if (otherPartyPublicKey is ECDiffieHellmanCngPublicKey otherKey)
{
using (CngKey import = otherKey.Import())
{
return(DeriveKeyMaterial(import));
}
}
// This deviates from the .NET Framework behavior. .NET Framework can't handle unknown public
// key types, but on .NET Core there are automatically two: the public class produced by
// this class' PublicKey member, and the private class produced by ECDiffieHellman.Create().PublicKey
//
// So let's just work.
ECParameters otherPartyParameters = otherPartyPublicKey.ExportParameters();
using (ECDiffieHellmanCng otherPartyCng = new ECDiffieHellmanCng())
{
otherPartyCng.ImportParameters(otherPartyParameters);
using (otherKey = (ECDiffieHellmanCngPublicKey)otherPartyCng.PublicKey)
using (CngKey importedKey = otherKey.Import())
{
return(DeriveKeyMaterial(importedKey));
}
}
}