The Clipper Chip is a cryptographic device purportedly intended to protect private communications while at the same time permitting government agents to obtain the "keys" upon presentation of what has been vaguely characterized as "legal authorization." The "keys" are held by two government "escrow agents" and would enable the government to access the encrypted private communication. While Clipper would be used to encrypt voice transmissions, a similar chip known as Capstone would be used to encrypt data.
The underlying cryptographic algorithm, known as Skipjack, was developed by the National Security Agency (NSA), a super-secret military intelligence agency responsible for intercepting foreign government communications and breaking the codes that protect such transmissions. In 1987, Congress passed the Computer Security Act, a law intended to limit NSA's role in developing standards for the civilian communications system. In spite of that legislation, the agency has played a leading role in the Clipper initiative and other civilian security proposals, such as the Digital Signature Standard. NSA has classified the Skipjack algorithm on national security grounds, thus precluding independent evaluation of the system's strength.
EPIC filed a legal memorandum in federal court challenging the "national security" classification of information concerning the "Clipper Chip."
On April 16, 1993, the White House announced the Clipper Chip. A Factsheet was released setting out some of the reasons for the proposal and an Interagency Working Group was created to study the issue.
To gain support for the Clipper Chip, NIST commissioned a review of the algorithm by outside experts. The group released the SKIPJACK Review Interim Report on July 28, 1993 supporting the proposal.
On Feb. 4, 1994, the White House announced the adoption of the Clipper Chip. The adoption was supported by Vice President Gore. The White House released a factsheet of Questions and Answers on the decision.
Department of Commerce, FIPS 185 Approval of the Escrowed Encryption Standard (EES) (Feb 94) .
Attorney General Janet Reno announcement that NIST and the Department of the Treasury would be the key escrow holders . Reno also released the procedures for release of the keys to law enforcement officials for under Title III, state and national security wiretap orders.
NSA responses to written questions submitted by the Senate Judiciary Subcommittee on Technology and the Law (May 1994).
The Impact of a Secret Cryptographic Standard on Encryption, Privacy, Law Enforcement and Technology by Whitfield Diffie, Sun Microsystems, before US House of Representatives, 11 May 1993.
The Computer System Security and Privacy Advisory Board held several days of hearings on Clipper and on June 4, 1993 issued two resolutions criticizing the Clipper.
Archive of public comments submitted in response to NIST Clipper announcement.
Letter signed by cryptography, security and networking experts, January 1994. The letter was followed with a Electronic Petition to oppose Clipper. Eventually, over 50,000 people responded to the petition request.
Association for Computing Machinery, Codes, Keys and Conflicts (June 1994). ACM US Public Policy Committee (USACM) statement on Escrow Encryption Standard.
Transcript of Voice of America show on Clipper with CPSR's David Sobel and NIST's Lynn McNulty.
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