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

public static class CryptoUtility
{
    private static readonly string key = "1234567890123456"; 


    public static string Encrypt(string plainText)
    {
        byte[] keyBytes = Encoding.UTF8.GetBytes(key);
        using Aes aes = Aes.Create();
        aes.Key = keyBytes;
        aes.IV = keyBytes;

        using MemoryStream ms = new MemoryStream();
        using CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write);
        using (StreamWriter sw = new StreamWriter(cs))
        {
            sw.Write(plainText);
        }

        return Convert.ToBase64String(ms.ToArray());
    }

    public static string Decrypt(string encryptedText)
    {
        byte[] keyBytes = Encoding.UTF8.GetBytes(key);
        using Aes aes = Aes.Create();
        aes.Key = keyBytes;
        aes.IV = keyBytes;

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

        using MemoryStream ms = new MemoryStream(buffer);
        using CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Read);
        using StreamReader sr = new StreamReader(cs);
        return sr.ReadToEnd();
    }
}