Accessing Password_hash By Users In SQL Server 2005

In SQL Server 2000 we had a view that would show the user credentials and the password hash. The reason we need this is that we use SQL Server authentication on the database. To test users, we have a login with little access, and it should be able to see the view and compare the password supplied against what is in the database, and then let the code handle a graceful exit if the password is invalid. I am trying to do this with SQL Server 2005, and I am running into trouble. I am trying to do this with a function, since there I can set the EXECUTE AS clause (in theory) and leverage the privlidges of a specific user in the database. Here is an example function:




CREATE FUNCTION check_acct.fn_allusers (@test int)
RETURNS @users table (username varchar(50), passwd varbinary(256))
WITH EXECUTE AS caller
AS
BEGIN
INSERT @users
select name, password_hash from sys.sql_logins
RETURN
END
GO
GRANT SELECT ON fn_allusers TO user_acct

I cannot get to all rows in the sys.sql_logins table unless I first:



GRANT VIEW ANY DEFINITION TO CHECK_ACCT



then when I call this function from CHECK_ACCT, I am able to see the data. If I change the WITH EXECUTE AS 'CHECK_ACCT' and execute thsi function from USER_ACCT, I do not get the same results. Do functions not inherit VIEW DEFINITION proivlidges? Any suggestions on how to do this but limit access to these secure objects to this one function?