Full disk encryption: Key on USB storage device

[DaveGK]

Jens Müller wrote:
> I want to encrypt my Netbooks HDD.
> 
> If I understand 
> http://kuparinen.org/martti/comp/ubuntu/en/cryptolvm.html correctly, 
> that is possible with the Alternate install CD.
> 
> But what I miss: Is it possible to put the key file onto a USB stick so 
> that it is loaded automatically from there at boot time? Long time ago, 
> I looked at the Gentoo initrd script, which apparently supports this.
> 
> A bit more sophisticated: Is it possible to put the whole boot partition 
> including the key file onto a USB drive?
> 
> I also found https://wiki.ubuntu.com/SmartCardLUKSDiskEncryption, which 
> sounds nice. Are there such smartcards in the form of a self-contained 
> USB device which I can put on my keyring?

Could I add a follow-up question to this?
Is it possible to put the key or, better still, the boot partition and 
the key on an SD card instead of USB stick? I'm pretty sure my laptop 
can boot from built-in card reader - will check tomorrow :)

-- 
Cheers,
Dave