Keystroke logging is a national security issue

Remember the case of the gangster using PGP, only to be caught when the FBI used a keystroke logger to get his passphrase? Well, now the Feds say how their keystroke logger works is a national security issue, and have motioned to keep their system's details secret in the case of Nicodemo Little Nicky Scarfo Jr., accused bookie and son of a jailed mob boss. How complex and special could their system be, anyway? [thanks, hackinthebox.org]