How can I use a keyfile on a removable USB drive for my encrypted root in Debian?

Recently set up root encryption with a couple of LVM volumes inside one LUKS volume, and I am just a little confused as to how I would go about getting it to automatically unlock using a keyfile stored on a USB flash drive, I presume I would have to put the drive in the fstab inside my initramfs (if there is one), and add a hook for USB device support.

But I digress, essentially, I want to know what I have to do to enable my LUKS volume (containing all of my partitions sans /boot) to unlock using a keyfile stored on a USB flash drive, rather than a manually entered passphrase.

Solution 1:

solved on ubuntu...might require a little tweaking for debian, but you get the idea http://ubuntuforums.org/showthread.php?t=843571

note you wouldn't need the mmc options added to ramdisk as he did in that tutorial since usb should already be loaded anyway...if it isn't you might need to add that module instead