Spy Expert David Kahn Says We Need Scrambled Phones to Avoid Serving Up Info to the Soviets

updated 12/03/1984 AT 01:00 AM EST

originally published 12/03/1984 AT 01:00 AM EST

Recently the supersecret National Security Agency (NSA) sent a letter to 2,000 private businesses and gave unprecedented interviews saying that U.S. security was "in deep trouble." The reason: The Soviet Union is spying on our government and major corporations by tapping American phones. The agency proposed a cure for this "hemorrhaging" of information: half a million new "secure" phones for both government and private industry.

One who read the NSA's plea with fascination was David Kahn. The Oxford-educated Kahn, an editor for Long Island's Newsday, is the author of The Codebreakers, a popular text on codes and ciphers. He is also co-editor of the quarterly magazine Cryptologia and this year is teaching a course at Yale in political and military intelligence. Kahn agrees with the NSA that phone taps provide the Soviets with "clues to our high technology, governmental defense contracting, agricultural and economic data." He talked with Assistant Editor David Van Biema about the NSA's plan to "scramble" such Russian designs.

Since the NSA gave no concrete examples of phone tapping, how seriously should we take its warning?

Quite seriously. The government doesn't like to name specific incidents because it would give away our counterintelligence. But Soviet phone tapping has been going on for maybe 20 years, ever since the Soviets figured out how to exploit our microwave phone system. Before World War II all phone calls went out over wires laid end-to-end across the country. To tap such a phone, you'd have to physically contact the wire. But after World War II, the volume of calls made it necessary to set up microwave towers, which send and receive millions of calls hourly. To "tap" microwaves, you don't need physical contact. If you have sensitive receivers, you can pick up the signals anywhere within 10 miles of either side of the microwave beam. And the Soviets do.

Out of so many calls, how do they pick the ones they want?

They have computers that target their eavesdropping according to call destination. When a Soviet computer monitoring the microwaves between New York and Washington hears the phone number beeps for, say, the Defense Department, it activates a tape recorder. According to one Soviet defector, truckloads of tapes are then taken to Kennedy Airport under diplomatic seal and shipped to the U.S.S.R. to be analyzed.

Where do the Soviets do their listening?

The best-known "listening post" is in the attic of the Soviet weekend retreat in Glen Cove, Long Island. Presumably the Soviets are tapping calls from defense contractors in Connecticut, financial centers in New York and the high-tech regions around Boston to government offices in Washington. They also have intercept posts at their properties in the Bronx, on the eastern shore of Chesapeake Bay and on Green Street in San Francisco.

From those posts the Soviets get the jump on new technologies?

Not all at once. It's a kind of massive, glacial flow of information. The Soviets pick up little bits and pieces here and there and eventually create a revealing mosaic. That's why the NSA wants to spread scramblers widely through industry—to shut down the various sources for the little bits and pieces.

What is a scrambler?

The best scramblers take the voice, assign it digits according to its frequency and then mix them with other digits according to a predetermined formula or key. The result sounds like a low hum or buzz. Another scrambler on the other end of the line reverses the process.

Why aren't all important phone calls scrambled?

Some are. The President, Cabinet members, heads of the armed services, arms control officials and, in private industry, perhaps a few oil companies use them. But until recently, the cost of good scramblers has been prohibitive. The only ones that would give any protection cost $10,000 to $30,000 and the most effective ones, like those the President uses, must cost at least $100,000. The NSA has commissioned several companies to see if in two years scramblers can be made for around $2,000. If this can be done, it may be easier for the government to sell the idea.

Easy, but not a shoo-in?

They're going to have a hell of a time persuading private industry to go along. It's extra work and when your scramblers get out of synchronization, you have to start the procedure and phone call all over again. And the cost of the machines themselves is only the beginning. There's constant servicing. The expense and delay will cut into the profits of those companies that use them. As far as anybody can determine, most large companies don't tap each other's phones, so there's no impetus to protect information from the competition. And a small bit of information leaked to the Russians probably won't hurt any individual company.

Is it critical that the NSA's plan succeed?

To have more secure phones for the government is necessary. But if the NSA is unsuccessful in placing hundreds of thousands of more secure phones in private industry, I don't think we should be frightened. The Soviets do listen in on American industry and do profit from what they hear, but it's an eternal game of catch-up. The intercommunications, freedom of the press and conversations among scientists in America provide a kind of intellectual ferment that keeps us going. You don't have that in the Soviet Union. As long as the situation stays that way, we'll stay ahead. By listening, the Soviets will skim off some cream, but they'll always be behind.

Why can't we just force the Russians to stop listening?

I think the basic reason is that if we kicked them out, they'd kick us out. And we may well be doing the same thing over there.

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