Is Transport security a bad practice for the WCF service over the Internet?

Question

I have a WCF service accessible over the Internet. It has wsHttpBinding binding and message security mode with username credentials to authenticate clients. The msdn says that we should use message security for the Internet scenarios, because it provides end-to-end security instead of point-to-point security as Transport security has.

What if i use transport security for the wcf service over the Internet? Is it a bad practice? Could my data be seen by malicious users?

Answer 1

No, it would be a good practice - trouble is: you cannot guarantee a complete chain of secure connections over an arbitrary number of intermediate hops when you're dealing with an internet connection.

All you can guarantee with transport security is the link from your client to the first hop, and the link from the last hop to your server - anything in between is beyond your control. So basically, transport security over the internet is not going to work - unless you have a strictly controlled environment where you know the client connects very directly to your servers.

Due to those technical limitations, transport security only really works in corporate / LAN environments. As soon as you have no control over the routing and the intermediary hops, you need to use message security for an end-to-end security.

Answer 2

Yes it is 100% secure when the clients (which most clients do) validate the server certificate.

The multiple hop scenario mentioned here is complete bogus. This is only true when the same message travels through various applications. Like for example several application brokers. If these brokers do not communicate securely then the message can be read by intermediate network sniffers.

In other words, client/server communication over the internet is 100% secure even when there are a million routers in between but it is only secure when the client validates the server certificate as the client could connect to a man-in-the-middle host that could impersonate the server with a false certificate. If the client does not validate the certificate the message could be compromised.