simple security related question

[Software Expert]

Hi,

I have a simple security related question.

I have two applications:

1. A ASP.NET web application.
2. A ASP .NET WebService. The methods of the WebService is used by the .NET
application.

The ASP .NET application has it's user verification and security module in
place. From that application I am consuming the .NET webservice. The .NET
WebService has it's own user verification and security module. Now when I
consume the webservice the user verification process is performed twice.
Once I logon to the ASP.NET application and and again when I use the
webservice. Is there anyway we can have a single user verification process
without sacrificing all the security issues?

regards,
Joydeep