"You have no need to know" is a phrase used by "certain people" when they know something you probably do need to know, but the chances of their actually telling you are somewhere between "slim" and "none".

See also: CIA, KGB, MI6, NSA, DIA, NRO, Intellegence, Spys, Espionage, Alphabet soup, and They threw me out! They called me MAD! Said I was a bleedin' security risk, the bastards...