how to add simple security and measure performance of web service

So I'm making a app for a bank, but it doesnt manage very important data. I have two problems, it will run over a VERY large LAN network protected by all kinds of security(antivirus and firewalls) and the bandwidth in certain regions is as low as 56kbps.(Its a desktop app with a web server backend connected by web services)

From the security point of view all I want is to prevent someone from executing the web services from some other source or app results in change in the database . I'm thinking of each desktop app installed with a install code, this will be hashed and required as a parameter for every function call and will act as an authentication ticket? Is this good enough? Are they better SIMPLER means?

For performance, how do I measure or know i开发者_JS百科f the web service will send and receive data at a decent rate?

Thanks

Gideon

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Assuming you are on a windows domain. You could configure the server to use windows authentication and restrict the users which can access the web service.

For performance measuring - asp.net will show you a sample request and response if you hit the web service from a browser, you can work out the site of a message and use the bandwidth to calculate how long it should take. You could also call the web service and use the stopwatch class to measure the time it takes.

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I would prefer assigning usernames and passwords. Either way, the user can disclose their code to someone else. And either the user or a recipient can access the app using other programs (there's no way to prevent someone extracting an install code). But if you assign usernames, they are more likely to take personal responsibility for what happens using the authorization.