We developed a web service which is accessed by various platforms clients, for example it is requested by c++ and Java enabled clients.
I want to use simple, effective encryption Algorithm which is easily decrypted by JAVA – C++ and JAVA script based clients.
If you already have the service implementation which is Base profile compliant and you want to keep on supporting various platform clients, extend your current service with WS-Security/WS-Trust. This will allow for encrypting/signing the content of the message, without loosing interoperability.
Depending on which toolset you used for your original implementation, the inclusion of WS-Security can be as easy as ‘flicking a switch and selecting some options in your configuration file’ (WCF/ASMX+WSE).
Since you mention the various platforms client side, I assume this is one of your main requirements.
Hope this helps.