using System;

using System.Text;

​

using Org.BouncyCastle.Crypto.Engines;

using Org.BouncyCastle.Crypto.Modes;

using Org.BouncyCastle.Crypto.Parameters;

using Org.BouncyCastle.Crypto;

public class Program

{

    public static void Main()

    {

        string plaintext = "The quick brown fox jumps over the lazy dog";

        string key = "01234567890123456789012345678901";

        string cfb_iv = "0123456789012345";

        string ciphertext = Encrypt(plaintext, key, cfb_iv);

        Console.WriteLine(ciphertext);

    }

    public static string Encrypt(string str, string keyString, string IVString)

    {

        byte[] inputBytes = Encoding.UTF8.GetBytes(str);

        byte[] IV = Encoding.UTF8.GetBytes(IVString);

        byte[] key = Encoding.UTF8.GetBytes(keyString);

​

        AesEngine engine = new AesEngine();

        CfbBlockCipher blockCipher = new CfbBlockCipher(engine, 128);

        BufferedBlockCipher cipher = new BufferedBlockCipher(blockCipher);

        KeyParameter keyParam = new KeyParameter(key);

        ParametersWithIV keyParamWithIv = new ParametersWithIV(keyParam, IV);

​

        cipher.Init(true, keyParamWithIv); 

        byte[] outputBytes = new byte[cipher.GetOutputSize(inputBytes.Length)]; 

        int length = cipher.ProcessBytes(inputBytes, outputBytes, 0);

        cipher.DoFinal(outputBytes, length);

        string encryptedInput = ToBCDStringLower(outputBytes);

​

        return encryptedInput;

    }

    public static string ToBCDStringLower(byte[] buffer)

    {

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < buffer.Length; i++)

        {

            sb.Append(buffer[i].ToString("x2"));

        }

        return sb.ToString();

    }

}