<PackageReference Include="BouncyCastle.Cryptography" Version="2.4.0" />

Org.BouncyCastle.Tls.Crypto.TlsHmac

public interface TlsHmac : TlsMac
Interface for MAC services based on HMAC.
int InternalBlockSize { get; }

Return the internal block size for the message digest underlying this HMAC service.