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

public static class EncryptionHelper
{
    static readonly string PasswordHash = "The pAsswordHash";
    static readonly string SaltKey = "tHe sAltkEy5983479857349802759837";
    static readonly string CustomKey = "HR$2pIjHR$2pIj12";

    public static string Encrypt(string plainText)
    {
        byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);

        byte[] keyBytes = new Rfc2898DeriveBytes(PasswordHash, Encoding.ASCII.GetBytes(SaltKey)).GetBytes(256 / 8);
        using (var symmetricKey = Aes.Create())
        {
            symmetricKey.Padding = PaddingMode.Zeros;
            var encryptor = symmetricKey.CreateEncryptor(keyBytes, Encoding.ASCII.GetBytes(CustomKey));

            byte[] cipherTextBytes;

            using (var memoryStream = new MemoryStream())
            {
                using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                {
                    cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                    cryptoStream.FlushFinalBlock();
                    cipherTextBytes = memoryStream.ToArray();
                    cryptoStream.Close();
                }
                memoryStream.Close();
            }
            return Convert.ToBase64String(cipherTextBytes);
        }
    }

    public static string Decrypt(string encryptedText)
    {
        byte[] cipherTextBytes = Convert.FromBase64String(encryptedText);
        byte[] keyBytes = new Rfc2898DeriveBytes(PasswordHash, Encoding.ASCII.GetBytes(SaltKey)).GetBytes(256 / 8);

        using (var symmetricKey = Aes.Create())
        {
            symmetricKey.Padding = PaddingMode.Zeros;
            var decryptor = symmetricKey.CreateDecryptor(keyBytes, Encoding.ASCII.GetBytes(CustomKey));
            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());
        }
    }
}