using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Security.Cryptography;

using System.IO;

public class Program

{

    static readonly string PasswordHash = "P@@Sw0rd";

    static readonly string SaltKey = "S@LT&KEY";

    static readonly string VIKey = "@1B2c3D4e5F6g7H8";

    public static void Main()

    {

        Console.WriteLine(Decrypt("bgjAscTAw/GlOLbATUkz2A=="));

    }

    public static string Decrypt(string encryptedText)

        {

            byte[] cipherTextBytes = Convert.FromBase64String(encryptedText);

            byte[] keyBytes = new Rfc2898DeriveBytes(PasswordHash, Encoding.ASCII.GetBytes(SaltKey)).GetBytes(256 / 8);

            var symmetricKey = new RijndaelManaged() { Mode = CipherMode.CBC, Padding = PaddingMode.None };

​

            var decryptor = symmetricKey.CreateDecryptor(keyBytes, Encoding.ASCII.GetBytes(VIKey));

            var memoryStream = new MemoryStream(cipherTextBytes);

            var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read);

            byte[] plainTextBytes = new byte[cipherTextBytes.Length];

​

            int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);

            memoryStream.Close();

            cryptoStream.Close();

            return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount).TrimEnd("\0".ToCharArray());

        }

}