Security C#

using System;
using System.Net;
using System.Security.Cryptography;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
namespace Bonefisher.Silverlight.Utilities
{
    public static class PasswordEncrypter
    {
        public static string Encrypt(this string plaintextPassword)
        {
            HashAlgorithm mhash = new SHA1Managed();
            byte[] bytValue = Encoding.UTF8.GetBytes(plaintextPassword);
            byte[] bytHash = mhash.ComputeHash(bytValue);
            mhash.Clear();
            return Convert.ToBase64String(bytHash);
        }
    }
}