Clipper Chip

The Clipper Chip was a hardware encryption device proposed by the U.S. National Security Agency in 1993 as a voluntary standard for telecommunications. It used the classified Skipjack cipher and a key-escrow design in which every chip's session key was held — split between two federal agencies — and could be reassembled to decrypt any conversation under legal process.

The proposal was the most direct attempt in modern history to mandate a structural backdoor in civilian cryptographic infrastructure, and the public fight over it defined the first phase of the crypto-wars. The cypherpunk movement, the Electronic Frontier Foundation, and a coalition of civil-liberties groups, telecommunications companies, and academic cryptographers argued that key escrow created a single high-value target whose compromise would expose every communication made under the system. The technical case became decisive in 1994 when Matt Blaze published a vulnerability in the Escrowed Encryption Standard that allowed users to defeat the escrow while still appearing to comply.

By 1996 the proposal was dead — but the policy argument keeps returning. "Exceptional access," "responsible encryption," "ghost users" — each generation of legislation proposes a new mechanism that key holders can be compelled to use against the user, and each runs into the same structural problem: a system that can be opened by an authorised party can be opened by an unauthorised one. The deployment of strong end-to-end cryptography is the only architecture that resolves the dilemma. Clipper is the canonical worked example.