Usually connection string in web config is not encrypted. For security purpose in
                asp.net 2.0 or upper version there is a functionality to encrtypt the connection
                string. The .NET Framework have two protected configuration providers:
                
                * RSAProtectedConfigurationProvider - uses the asymmetric RSA algorithm
                for encryption and decryption.
                
                * DPAPIProtectedConfigurationProvider - uses the Windows Data Protection
                API (DPAPI) for encryption and decryption.
                
                In this example we have made two methods for encryption and decryption and called
                on buttons. In working example you just need to extract the example and open as
                website and run. Changes will be seen in webconfig of example.
                
                There are two main functions in example named:
1) ProtectSection
2) UnProtectSection
                When you want to encrypt the connection string then call the first function and
                when you want to check the original values of the connections then call second function.
            
		
				 
		
            This is attached example's screen. On first button's click you can encrypt the connection
            string (app settings). After click on Encrypt Button you can check the effect on
            string in web.config.
Click here to see the working example in video