Need a file upload plugin and a way to authenticate from another app

Hey all,
i need to be able to create a mobile application that will upload a file
my rails site.
i need the application to authenticate and then upload.

I am using the basic roll-your-own authenticate system with a sessions
users controllers.

Any ideas where best to find a tutorial or gem that can help explain how
get started with something like this?


For authentication, I use devise, but you might use an authentication
method (though on a public network, you might want to use public/private
key pairs). Paperclip and Carrierwave are good gems for file uploads.