Informix Connection Strings

All, I'm very new to Informix and have been asked to produce a C# based Web Application that interfaces to an Informix 11.10 IDS Database. Due to security requirements I need to pass the current users credentials through to the database server. I do this on SQL Server by specifying "Integrated Security=True" in the connection string. Is there a way to do this with Informix, all the examples I have seen to date include the user name and Password hard coded in the connection string. Regards Mike