using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

public class Cryptography
{
    public static string EncryptString(string plainText, string key, string iv)
    {
        using (Aes aesAlg = Aes.Create())
        {
            aesAlg.Key = GetKeyBytes(key, aesAlg.KeySize / 8);
            aesAlg.IV = GetKeyBytes(iv, 16);

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

            using (MemoryStream msEncrypt = new MemoryStream())
            {
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                {
                    byte[] plainBytes = Encoding.UTF8.GetBytes(plainText);
                    csEncrypt.Write(plainBytes, 0, plainBytes.Length);
                    csEncrypt.FlushFinalBlock();
                }
                return Convert.ToBase64String(msEncrypt.ToArray());
            }
        }
    }

    public static string DecryptString(string cipherText, string key, string iv)
    {
        byte[] cipherBytes = Convert.FromBase64String(cipherText);
        using (Aes aesAlg = Aes.Create())
        {
            aesAlg.Key = GetKeyBytes(key, aesAlg.KeySize / 8);
            aesAlg.IV = GetKeyBytes(iv, 16);

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

            using (MemoryStream msDecrypt = new MemoryStream(cipherBytes))
            {
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                    {
                        return srDecrypt.ReadToEnd();
                    }
                }
            }
        }
    }

    private static byte[] GetKeyBytes(string key, int keySize)
    {


        using (var deriveBytes = new PasswordDeriveBytes(key, null))
        {
            return deriveBytes.GetBytes(keySize);
        }
    }
}