using System;

using System.IO;

using System.Text;

using System.Security.Cryptography;

​

public class Program

{

    private static RijndaelManaged _alg = new RijndaelManaged();

    public static void Main()

    {

        _alg.Key = getKey();

        string ciphertext = "EAAAACMtkB64He4p/MSI+yF2A2rJWhxpssG6b48Z01JrfbErvQ1r6Gi0esgCmdrBaFxOPFF1+AUsyrUUl5FQ4Nk0dSU=";

        string decrypted = Decrypt(ciphertext);

        Console.WriteLine(decrypted);

        var salt = "1111111111111111";

        var saltBytes = Encoding.UTF8.GetBytes(salt);

        Test("12345", saltBytes, 1000, 128);

    }

​

    public static string Test(string key, byte[] salt, int iterations, int keysize)

    {

        using (Aes aes = new AesManaged())

        {

            aes.Padding = PaddingMode.PKCS7;

            aes.KeySize = keysize;

            Rfc2898DeriveBytes rfc2898 = new Rfc2898DeriveBytes(key, salt, iterations);

            aes.Key = rfc2898.GetBytes(aes.KeySize / 8);

            aes.IV = rfc2898.GetBytes(aes.BlockSize / 8);

            Console.WriteLine(Convert.ToBase64String(aes.Key));

            Console.WriteLine(Convert.ToBase64String(aes.IV));

        }

​

        return "";

    }

​

    private static byte[] getKey()

    {

        var secret = "D2s1d_5$_t0t3||y_4c3$0m3!1!1!!";

        var salt = "o6805542kcM7c5";

        var saltBytes = Encoding.ASCII.GetBytes(salt);

        using (var keyDeriver = new Rfc2898DeriveBytes(secret, saltBytes))

        {

            _alg.Key = keyDeriver.GetBytes(_alg.KeySize / 8); // _alg.KeySize = 256

        }

​

        return _alg.Key;

    }

​

    public static string Decrypt(string ciphertext)

    {

        var cipherTextBytes = Convert.FromBase64String(ciphertext);

        var ivSize = BitConverter.ToInt32(cipherTextBytes, 0);

        var iv = new byte[ivSize];

        var offset = sizeof(int);

        Array.Copy(cipherTextBytes, offset, iv, 0, ivSize);

        offset += ivSize;

        using (var msDecrypt = new MemoryStream(cipherTextBytes, offset, cipherTextBytes.Length - offset))

        {

            //lock (_syncLock)

            //{

            using (var decryptor = _alg.CreateDecryptor(_alg.Key, iv))

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

                    using (var reader = new StreamReader(decryptStream))

                    {

                        return reader.ReadToEnd();

                    }

        //}

        }

    }

}