using System.Security.Cryptography;

using System.Text;

using Org.BouncyCastle.Crypto.Parameters;

using Org.BouncyCastle.Security;

using System;

using System.IO;

public class Program

{

    public static void Main()

    {

        byte[] plaintext = Encoding.UTF8.GetBytes("{\"business_id\":\"3292aecc-886a-45e3-aa55-d3");

        byte[] iv = Convert.FromHexString("76396c566a476c4c50694e376469487a");

        byte[] key = Encoding.UTF8.GetBytes("ei9dzmx9f3l2CdFliYMb7iwJ7d0ce58d");

​

        // native C# methods (one shot)

        byte[] ciphertext_streams = AesEncrypt_streams(key, iv, plaintext);

        Console.WriteLine(Convert.ToBase64String(ciphertext_streams));

        byte[] decrypted_streams = AesDecrypt_streams(key, iv, ciphertext_streams);

        Console.WriteLine(Encoding.UTF8.GetString(decrypted_streams));

​

        // C#/BouncyCastle methods

        byte[] ciphertext_BC = AesEncrypt_BC(key, iv, plaintext);

        Console.WriteLine(Convert.ToBase64String(ciphertext_BC));

        byte[] decrypted_BC = AesDecrypt_BC(key, iv, ciphertext_BC);

        Console.WriteLine(Encoding.UTF8.GetString(decrypted_BC));

​

        // native C# methods (streams)

        byte[] ciphertext = AesEncrypt(key, iv, plaintext);

        Console.WriteLine(Convert.ToBase64String(ciphertext));

        byte[] decrypted = AesDecrypt(key, iv, ciphertext);

        Console.WriteLine(Encoding.UTF8.GetString(decrypted));

    }

    private static byte[] AesEncrypt(byte[] key, byte[] iv, byte[] plaintext)

    {

        byte[] ciphertext = null;

        using (Aes aesAlg = Aes.Create())

        {

            aesAlg.Key = key;

            ciphertext = aesAlg.EncryptCfb(plaintext, iv, PaddingMode.None, 8); 

        }

        return ciphertext; 

    }

​

    private static byte[] AesDecrypt(byte[] key, byte[] iv, byte[] ciphertext)

    {

        byte[] decrypted = null;

        using (Aes aesAlg = Aes.Create())

        {

            aesAlg.Key = key;

            decrypted = aesAlg.DecryptCfb(ciphertext, iv, PaddingMode.None, 8); 

        }

        return decrypted;

    }

    private static byte[] AesEncrypt_BC(byte[] key, byte[] iv, byte[] plaintext)

    {

        var cipher = CipherUtilities.GetCipher("AES/CFB8");

        cipher.Init(true, new ParametersWithIV(new KeyParameter(key), iv));

        return cipher.DoFinal(plaintext);

    }

​

    private static byte[] AesDecrypt_BC(byte[] key, byte[] iv, byte[] ciphertext)

    {

        var cipher = CipherUtilities.GetCipher("AES/CFB8");

        cipher.Init(false, new ParametersWithIV(new KeyParameter(key), iv));

        return cipher.DoFinal(ciphertext);

    }

    private static byte[] AesEncrypt_streams(byte[] key, byte[] iv, byte[] plaintext)

    {

        byte[] ciphertext = null;

        using (Aes aesAlg = Aes.Create())

        {

            aesAlg.Padding = PaddingMode.None; // must be specified, as PKCS#7 is the default // pad

            aesAlg.Mode = CipherMode.CFB; // must be specified, as CBC is the default

            aesAlg.FeedbackSize = 8; // must be specified, as CFB-8 is the default

            aesAlg.Key = key;

            aesAlg.IV = iv;

            ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

            using (MemoryStream msEncrypt = new MemoryStream())

            {

                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))

                {

                    csEncrypt.Write(plaintext);

                }

                ciphertext = msEncrypt.ToArray();

            }

            return ciphertext; 

        }

    }

​

    private static byte[] AesDecrypt_streams(byte[] key, byte[] iv, byte[] ciphertext)

    {

        byte[] decrypted = null;

        using (Aes aesAlg = Aes.Create())

        {

            aesAlg.Padding = PaddingMode.None; // must be specified, as PKCS#7 is the default

            aesAlg.Mode = CipherMode.CFB; // must be specified, as CBC is the default

            aesAlg.FeedbackSize = 8; // must be specified, as CFB-8 is the default

            aesAlg.Key = key;

            aesAlg.IV = iv;

            ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

            using (MemoryStream msDecrypt = new MemoryStream(ciphertext))

            {

                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))

                {

                    using (MemoryStream msDecryptForCpy = new MemoryStream())

                    {

                        csDecrypt.CopyTo(msDecryptForCpy);

                        decrypted = msDecryptForCpy.ToArray();

                    }

                }

            }

            return decrypted; 

        }

    }

}