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

[skrite]

Hey all, 

i need to be able to create a mobile application that will upload a file to 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 and users controllers. 

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

thanks

[dmt]

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