Core_Be/Helpers/EncryptionHelper.cs

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

public static class EncryptionHelper
{
    private static readonly byte[] Key = Convert.FromBase64String("6pY8vR2Nf+Xz9WkLm4TqQzB7vA9uS1nE5jR3hG6fM8o=");

    public static string Encrypt(string plainText)
    {
        using Aes aes = Aes.Create();
        aes.Key = Key;
        aes.GenerateIV();

        using var encryptor = aes.CreateEncryptor();
        byte[] plainBytes = Encoding.UTF8.GetBytes(plainText);
        byte[] cipherBytes = encryptor.TransformFinalBlock(plainBytes, 0, plainBytes.Length);

        return Convert.ToBase64String(aes.IV.Concat(cipherBytes).ToArray());
    }

    public static string Decrypt(string combinedText)
    {
        byte[] combinedBytes = Convert.FromBase64String(combinedText);
        using Aes aes = Aes.Create();
        aes.Key = Key;

        byte[] iv = combinedBytes.Take(16).ToArray();
        byte[] cipherBytes = combinedBytes.Skip(16).ToArray();

        using var decryptor = aes.CreateDecryptor(aes.Key, iv);
        byte[] plainBytes = decryptor.TransformFinalBlock(cipherBytes, 0, cipherBytes.Length);

        return Encoding.UTF8.GetString(plainBytes);
    }
}