On April 16, 1993, the Clinton White House announced the Clipper chip, an encryption microchip intended for secure telephones and other devices. The official statement was dated “For Immediate Release April 16, 1993” and presented the chip as a way to give Americans strong encryption while preserving law enforcement’s ability to wiretap with proper authorization (https://archive.epic.org/crypto/clipper/white_house_statement_4_93.html). The catch was a mechanism called key escrow: each chip’s keys would be split and held by government-designated escrow agents, so that with legal authorization the government could decrypt the traffic.
To privacy advocates and cryptographers this was a back door by design. The Electronic Frontier Foundation, which archived the primary documents from the fight, later summarized the proposal as “a plan for building in hardware backdoors to communications technologies,” resting on the promise that “only law enforcement with proper ‘legal authorization’ could access that key” (https://www.eff.org/deeplinks/2015/04/clipper-chips-birthday-looking-back-22-years-key-escrow-failures). The objection was not only philosophical: any escrow database and any back door is itself a target and a point of failure.
The technical case against Clipper was made decisively by AT&T researcher Matt Blaze, who showed that the underlying Escrowed Encryption Standard could be manipulated so the chip would encrypt data while defeating the escrow mechanism that was its entire justification. Combined with a broad public and industry backlash, documented across the EFF’s Clipper archive (https://w2.eff.org/Privacy/Key_escrow/Clipper/), the flaw was fatal to confidence in the scheme.
By 1996 the Clipper chip proposal was dead. It stands as the first major attempt to mandate a government back door into civilian encryption, and as a cautionary case study: the proposal foundered on the same problem that recurs whenever backdoors are proposed, that a deliberate hole in encryption cannot be reserved for the authorities alone.