<PackageReference Include="BouncyCastle.Cryptography" Version="2.3.1" />

Org.BouncyCastle.Crypto.Engines.XSalsa20Engine

public class XSalsa20Engine : Salsa20Engine
Implementation of Daniel J. Bernstein's XSalsa20 stream cipher - Salsa20 with an extended nonce.
namespace Org.BouncyCastle.Crypto.Engines { public class XSalsa20Engine : Salsa20Engine { public XSalsa20Engine(); } }