using System;

using System.Linq;

using System.Collections.Generic;

using System.Text.RegularExpressions;

using System.IO;

using System.Security.Cryptography;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        var message = "Hello World!";

        var fixedCipherText = Crypt.FixedEncryptor(message);

        var cipherText = Crypt.Encryptor(message);

        Console.WriteLine(cipherText);

        //var plainText = Crypt.Decryptor(cipherText);

        var fixedPlainText = Crypt.Decryptor(fixedCipherText);

        Console.WriteLine(fixedPlainText);

        //Console.WriteLine(plainText);

    }

}

​

public static class Crypt

{

    private const string password = "password";

    private readonly static byte[] salt = Encoding.ASCII.GetBytes(password.Length.ToString());

    public static string FixedEncryptor(string content)

    {

        var cipher = new RijndaelManaged();

        var plain = Encoding.Unicode.GetBytes(content);

        var key = new PasswordDeriveBytes(password, salt);

        using (var encrypt = cipher.CreateEncryptor(key.GetBytes(32), key.GetBytes(16)))

            using (var stream = new MemoryStream())

                using (var crypto = new CryptoStream(stream, encrypt, CryptoStreamMode.Write))

                {

                    crypto.Write(plain, 0, plain.Length);

                    crypto.FlushFinalBlock();

                    return Convert.ToBase64String(stream.ToArray());

                }

    }

​

    public static string Encryptor(string content)

    {

        var cipher = new RijndaelManaged();

        var plain = Encoding.Unicode.GetBytes(content);

        var key = new PasswordDeriveBytes("password", Encoding.ASCII.GetBytes("password"));

        using (var encrypt = cipher.CreateEncryptor(key.GetBytes(32), key.GetBytes(16)))

            using (var stream = new MemoryStream())

                using (var crypto = new CryptoStream(stream, encrypt, CryptoStreamMode.Write))

                {

                    crypto.Write(plain, 0, plain.Length);

                    crypto.FlushFinalBlock();

                    return Convert.ToBase64String(stream.ToArray());

                }

    }

​

    public static string Decryptor(string content)

    {

        var cipher = new RijndaelManaged();

        var encrypted = Convert.FromBase64String(content);

        var key = new PasswordDeriveBytes(password, salt);

        using (var decryptor = cipher.CreateDecryptor(key.GetBytes(32), key.GetBytes(16)))

            using (var stream = new MemoryStream(encrypted))

                using (var crypto = new CryptoStream(stream, decryptor, CryptoStreamMode.Read))

                {

                    byte[] plain = new byte[encrypted.Length];

                    int decrypted = crypto.Read(plain, 0, plain.Length);

                    string data = Encoding.Unicode.GetString(plain, 0, decrypted);

                    return data;

                }

    }

}