title: Protocol to secure a connection between a mobile device and a web service?
body: <p>I'm looking for a protocol to secure a connection between a mobile device and a web service.  I want to ensure that only the mobile device can perform actions on the web service and vice versa. Data doesn't need to be encrypted.</p>
  
  <p>I know Oauth, but it seems that it's more used to secure connections when you got 3 different entities (Server, Consumer and Auth). Here, the Consumer and the User would be the same person.</p>
  
  <p>Is there a simple protocol to do that (without requiring the user to login and then authorize the access token like it is the case for Oauth)?</p>
  
  <p>I need to use it on different plateforms, so the protocol needs to be available at least on iPhone and PHP.</p>