Example how to implement a token generator in Xamarin.Forms Applications. - http://julianocustodio.com/token

MainPage.xaml.cs

using OtpSharp;
using System.Threading;
using Xamarin.Forms;

namespace DemoToken
{
    public partial class MainPage : ContentPage
    {
        public string Codigo
        {
            get => _codigo;
            set
            {
                _codigo = value;
                OnPropertyChanged();
            }
        }
        private string _codigo;

        public string Segundos
        {
            get => _segundos;
            set
            {
                _segundos = value;
                OnPropertyChanged();
            }
        }
        private string _segundos;

        private readonly byte[] secretKey;
        private Totp totp;
        private Timer timer;


        public MainPage()
        {
            InitializeComponent();
        }
    }
}