the Clipper chip
lorecryptographygovernance & risk
The US government's 1993 proposal for encrypted telephony in which the encryption was strong but a copy of every key was held in escrow, so authorities could decrypt with legal authorisation.
It failed politically because a key held by someone else is not your key, and technically because Matt Blaze published a flaw in 1994 showing the escrow field could be manipulated to defeat the escrow function - the system broken on its own terms. Clipper is the reference point for every later proposal of the same shape, whatever it is called: lawful access, exceptional access, client-side scanning. The engineering objection has never changed - a mechanism built to be opened does not verify who is opening it.
Also known as: key escrow, skipjack, law enforcement access field, exceptional access