Getting User Guid From SharePoint

sharepoint_claims_guid.cs

public class SharepointHelper
{
        public static string UserName
        {
            get { return CurrentClaim.Value; }
        }

        private static SPClaim CurrentClaim
        {
            get { return SPClaimProviderManager.Local.DecodeClaim(SPContext.Current.Web.CurrentUser.LoginName); }
        }

        public static Guid UserId
        {
            get
            {
                if( IsWindowsAuthenticated)
                {
                    using (HostingEnvironment.Impersonate())
                    {
                        var securityIdentifier =
                            SPActiveDirectoryClaimProvider.GetSecurityIdentifierFromClaim(CurrentClaim);
                        return new DirectoryEntry(string.Format("LDAP://<SID={0}>", securityIdentifier.Value)).Guid;
                    }
                }

                return (Guid) Membership.GetUser(UserName).ProviderUserKey;
            }
        }

        public static bool IsWindowsAuthenticated
        {
            get { return SPOriginalIssuers.GetIssuerType(CurrentClaim.OriginalIssuer) == SPOriginalIssuerType.Windows; }
        }
}