<PackageReference Include="BouncyCastle.Cryptography" Version="2.6.1" />

IBlockCipher

public interface IBlockCipher
namespace Org.BouncyCastle.Crypto { public interface IBlockCipher { string AlgorithmName { get; } void Init(bool forEncryption, ICipherParameters parameters); int GetBlockSize(); int ProcessBlock(byte[] inBuf, int inOff, byte[] outBuf, int outOff); } }