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I have a RFID reader interfaced with an Arduino microcontroller left over from a past project, which I would now like to use to automatically login on Ubuntu 11.10. What I'm imagining specifically is that I would start up my computer normally, it would get to the login screen for Ubuntu, I would swipe my RFID card and Ubuntu would then begin loading the desktop and everything as though I had typed in my password.

I have a python script already made that can read the RFID tag and use it to decrypt my password, and I can set it up to run when the computer starts up. I just have no idea what scripts Ubuntu runs when a user logs in.

Basically, all I need to know is what to add to my script so Ubuntu will load my profile and desktop as though I had just entered my password on the normal login screen.

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You would probably have to come up with something that hooks into PAM (Pluggable Authentication Module). For obvious reasons, authentication mechanisms are quite tricky to deal with. I suggest reading up on all things related to PAM and then hooking in to your welcome screen, which is likely lightdm unless you've changed it.

Aside from that your project is really cool (which it is!), I would cautiously recommend against securing your system solely with a physical object that someone can steal or borrow, since it would give them access to everything on your computer should they obtain it.

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Awesome, I will get to reading up on PAM and lightdm. Thanks for pointing me in the right direction! I really just had no idea where to start. And you are absolutely right about the security issue. I have most of my important files encrypted and I wouldn't plan on bringing the rfid reader outside of my house, so I'm not overly concerned about it though. I'm mostly interested in doing this for learning more about linux/the coolness factor rather than practical reasons, haha. – user857160 Feb 17 '12 at 0:34

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