Secure Class Library Settings class - Help

 Hi Guys,
 any help with this would be amazing.
I have a website which uses a class library this class library includes a soap based webservices which requires a username and password being passed for each function. I am currently storing the username and password within the class library app.config file (Properties.Settings class). if someone has access to my code/the dll they can disassmeble it and get the username and password. what is the best way to secure this information within the dll without encrypting the whole dll file??
any help please?
 
Lee

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