Hi I am developing my application in flex and JSP, so when I am passing values through HTTP Service Post method with request object but these values are tracing and modifying by testing team so I am planning to encrypt values in flex and decrypt it in jsp.so is there any algorithms like SHA or MD5 more secure algorithms, so please send any code or related links it is very useful to me. I am using like

httpService = new HTTPService;
httpService.request = new Object;
httpService.request.task = "doInvite";
httpService.request.email = emailInput.text;
httpService.request.firstName = firstNameInput.text;
httpService.request.lastName = lastNameInput.text;
httpService.send();

So is there any other way to give more secure ,please help me in this,Thanks in Advance.