Web Service Authentication

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Security.Cryptography;
using System.Text;

namespace WebServiceAuthentication
{
	public class TestAuth : System.Web.UI.Page
	{
		protected System.Web.UI.WebControls.Label LabelSrv;
		protected System.Web.UI.WebControls.TextBox TextBoxService;
		protected System.Web.UI.WebControls.Label LabelUser;
		protected System.Web.UI.WebControls.Label LabelPwd;
		protected System.Web.UI.WebControls.TextBox TextBoxPwd;
		protected System.Web.UI.WebControls.TextBox TextBoxUserName;
		protected System.Web.UI.WebControls.Button ButtonGetToken;
		protected System.Web.UI.WebControls.Label LabelToken;
		protected System.Web.UI.WebControls.TextBox TextBoxToken;
		protected System.Web.UI.WebControls.Button ButtonService;
		protected System.Web.UI.WebControls.Button ButtonUseToken;
		protected System.Web.UI.WebControls.Label ServResponse;
		protected System.Web.UI.WebControls.Button ButtonAuth;
	
		private void Page_Load(object sender, System.EventArgs e)
		{
			if (!Page.IsPostBack)
			{
				//JUST FOR TEST: set the correct UserName & Password
				this.TextBoxUserName.Text="MyUserName";
				this.TextBoxPwd.Text="SeCrEt";
			}
		}

		#region Web Form Designer generated code
		override protected void OnInit(EventArgs e)
		{
			//
			// CODEGEN: This call is required by the ASP.NET Web Form Designer.
			//
			InitializeComponent();
			base.OnInit(e);
		}
		
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{    
			this.ButtonAuth.Click += new System.EventHandler(this.ButtonAuth_Click);
			this.ButtonService.Click += new System.EventHandler(this.ButtonService_Click);
			this.ButtonGetToken.Click += new System.EventHandler(this.ButtonGetToken_Click);
			this.ButtonUseToken.Click += new System.EventHandler(this.ButtonUseToken_Click);
			this.Load += new System.EventHandler(this.Page_Load);

		}
		#endregion

		private void ButtonAuth_Click(object sender, System.EventArgs e)
		{
			string ret;
			string UserName, Password, Key, ToHash;

			UserName=this.TextBoxUserName.Text;
			Password=this.TextBoxPwd.Text;
			DateTime dt = DateTime.Now;
			ToHash=UserName.ToUpper()+"|"+Password+"|"+dt.ToString("yyyyMMdd")+"|"+dt.ToString("HHmm");
			Key=Hash(ToHash)+"|"+UserName+"|I would like to log this string in a DB";

			ServicePointReference.ServicePoint Authenticate = new ServicePointReference.ServicePoint();
			ret=Authenticate.Authenticate(Key);
			if (ret==null)
				this.ServResponse.Text="NULL RECEIVED!!"; //never!
			else
			{
				this.ServResponse.Text="RECEIVED DATA: "+ret;
			}
		}

		private void ButtonGetToken_Click(object sender, System.EventArgs e)
		{
			string ret;

			ServicePointReference.ServicePoint Authenticate = new ServicePointReference.ServicePoint();
			ret=Authenticate.GetToken();
			this.TextBoxToken.Text=ret;
		}

		private void ButtonService_Click(object sender, System.EventArgs e)
		{
			string ret;
			string UserName, Password, ServiceName;
			string Key, ToHash;

			UserName=this.TextBoxUserName.Text;
			Password=this.TextBoxPwd.Text;
			ServiceName=this.TextBoxService.Text;
			DateTime dt = DateTime.Now;
			ToHash=UserName.ToUpper()+"|"+Password+"|"+dt.ToString("yyyyMMdd")+"|"+dt.ToString("HHmm");
			Key=Hash(ToHash)+"|"+UserName+"|I would like to log this string in a DB";

			ServicePointReference.ServicePoint Authenticate = new ServicePointReference.ServicePoint();
			ret=Authenticate.UseService(Key, ServiceName);
			this.ServResponse.Text=ret;
		}

		private void ButtonUseToken_Click(object sender, System.EventArgs e)
		{
			string ret;
			string UserName, Password, ServiceName, Token;
			string Key, ToHash;

			UserName=this.TextBoxUserName.Text;
			Password=this.TextBoxPwd.Text;
			ServiceName=this.TextBoxService.Text;
			Token=this.TextBoxToken.Text;
			ToHash=UserName.ToUpper()+"|"+Password+"|"+Token;
			Key=Hash(ToHash)+"|"+UserName+"|I would like to log this string in a DB";

			ServicePointReference.ServicePoint Authenticate = new ServicePointReference.ServicePoint();
			ret=Authenticate.UseService(Key, ServiceName);
			this.ServResponse.Text=ret;
		}

		private string Hash(string ToHash)
		{
			// First we need to convert the string into bytes, which means using a text encoder.
			Encoder enc = System.Text.Encoding.ASCII.GetEncoder();

			// Create a buffer large enough to hold the string
			byte[] data = new byte[ToHash.Length];
			enc.GetBytes(ToHash.ToCharArray(), 0, ToHash.Length, data, 0, true);

			// This is one implementation of the abstract class MD5.
			MD5 md5 = new MD5CryptoServiceProvider();
			byte[] result = md5.ComputeHash(data);

			return BitConverter.ToString(result).Replace("-", "").ToLower();
		}

	}
}