6.805/STS085: 1994: Clipper (The Escrowed Encryption Standard)

In his LA speech, Gore called the development of the NII "a revolution." And it is a revolutionary war we are engaged in here. Clipper is a last ditch attempt by the United States, the last great power from the old Industrial Era, to establish imperial control over cyberspace. If they win, the most liberating development in the history of humankind could become, instead, the surveillance system which will monitor our grandchildren's morality. We can be better ancestors than that.
--John Perry Barlow, "Jackboots on the Infobahn," Wired, April 1994

The Clinton administration has adopted the chip, which would allow law enforcement agencies with court warrants to read the Clipper codes and eavesdrop on terrorists and criminals. But opponents say that, if this happens, the privacy of law-abiding individuals will be a risk. They want people to be able to use their own scramblers, which the government would not be able to decode. If the opponents get their way, however, all communications on the information highway would be immune from lawful interception. In a world threatened by international organized crime, terrorism, and rogue governments, this would be folly.
--Dorothy Denning, "The Clipper Chip will block crime," Newsday, Feb. 22, 1994

Of course there are people who aren't prepared to trust the escrow agents, or the courts that issue warrants, or the officials who oversee the system, or anybody else for that matter. Rather than rely on laws to protect us, they say, let's make wiretapping impossible; then we'll be safe no matter who gets elected. This sort of reasoning is the long-delayed revenge of people who couldn't go to Woodstock because they had too much trig homework. It reflects a wide -- and kind of endearing -- streak of romantic high-tech anarchism that crops up throughout the computer world.
--Stewart Baker, "Don't Worry Be Happy: Why Clipper Is Good For You," Wired, June, 1994

Overview of Clipper during 1994

The debate over the Digital Telephony Bill was carried out in the shadow of the much more public controversy over the Clipper Chip, which was authorized by the Clinton White House in April, 1993, and emerged as a full-fledged approved program -- the Escrowed Encryption Standard (EES) -- in February, 1994. Clipper, developed by the NSA, was system of encryption for telephone communications. It provided security through encryption, but arranged for the encryption keys to be held (in "escrow") by the government, so that they could be obtained for conducting wiretaps. This was to be accomplished through a special chip (the Clipper Chip) that would be installed in every telephone.

Clipper sparked enormous criticism. In addition to the overall issues about encryption and wiretapping, the specific proposal had fatal flaws:

These flaws were so serious that in retrospect it one wonders whether the NSA was so naïve as to seriously believe that Clipper would be adopted, or whether they merely put it forth as a ploy to elicit the emergence of practical proposals. In addition, there were several embarrassing developments, including the discovery of an attack on the Clipper protocol by Matt Blaze of Bell Labs, which would permit a determined hacker to subvert the escrow provisions of a Clipper phone (the NSA said they had known that all along) and the announcement by Prof. Silvio Micali of MIT that he held a patent on the key-splitting technique used in Clipper (the National Institute of Standards and Technology bought him off by licensing the patent).

In any event, by July of 1994 the Administration was already backing away from Clipper (note the July 20th letter from Vice President Gore and the follow-up articles in the news items from 1994) in favor of software-based "key escrow", which is the subject of the next section this essay.

More detailed information on Clipper in 1994

Although the details of Clipper changed in subsequent proposals, the debates during 1994 are still very pertinent, since they surfaced the general issues concerning government control of cryptography.

Papers, articles, and comments

News articles

Here are some items culled from the Net during 1994. Skimming them in chronological order will give you a good feel for how the Clipper controversy evolved over that first year.


Clipper was the subject of many debates and panels. Here are two of them:

Policy Studies

The Clipper debates engendered several significant studies of government encryption policy. (These are of historical interest in tracking the debate, but they are largely superseded by the 1996 report of the National Research Council.)

EPIC's FOIA request and lawsuit

In August 1995, the Electronic Privacy Information Center obtained documents under the Freedom of Information Act revealing that the FBI had concluded in 1993 that the Clipper initiative could succeed only if alternative security techniques were outlawed, and planned to push for such legislation (which they have since done). The existence of these plans, even while while the Administration was assuring people throughout 1994 that there were no plans to impose domestic control of encryption, has led to an atmosphere of distrust that continues to envelop the encryption debate. Here is EPIC's press release. In September 1995, EPIC filed a lawsuit against the NSA challenging the "national security" classification of information concerning the Clipper Chip and the underlying Skipjack algorithm.

More sources on Clipper

The Clipper/EES/Capstone/Tessera/Key Escrow Archive maintained by the Electronic Frontier Foundation contains extensive source material on Clipper from 1993 and 1994.

Next section of this essay: 1995-97: From Clipper to Key Recovery

Hal Abelson (hal@mit.edu)
Mike Fischer (mfischer@mit.edu)
Joanne Costello (joanne@mit.edu)

Last modified: Sat, 8 Oct 2005 15:21:41 -0400