Validation of users through sys.dba_users

We have an Oracle*Forms 4.5 App that allows a second user (other than the person login to app) to verify a record. We allow this by prompting the second user for their user name and password. One way to verify their account is to spawn another form using their username/password. If it connected then we have a valid user otherwise we have invalid user. This approach is fine except response time is slow. An alternative would be to use the following select statement:

select 'X'
from sys.dba_users
where username = 'XYZ'
and password = some_function('password');

This is much faster, but problem is we don't know the name for "SOME_FUNCTION".
Does anybody know the name to this function or an alternative method to handle this problem.

		Thank You
		Korosh