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Blown to Bits

Your Life, Liberty, and Happiness After the Digital Explosion

Hal Abelson Ken Ledeen Harry Lewis

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Library of Congress Cataloging-in-Publication Data:

Abelson, Harold. Blown to bits : your life, liberty, and happiness after the digital explosion / Hal Abelson,

Ken Ledeen, Harry Lewis. p. cm.

ISBN 0-13-713559-9 (hardback : alk. paper) 1. Computers and civilization. 2. Information technology--Technological innovations. 3. Digital media. I. Ledeen, Ken, 1946- II. Lewis, Harry R. III. Title.

QA76.9.C66A245 2008 303.48'33--dc22


Copyright ? 2008 Hal Abelson, Ken Ledeen, and Harry Lewis This work is licensed under the Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. To view a copy of this license visit or send a letter to Creative Commons 171 Second Street, Suite 300, San Francisco, California, 94105, USA.

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ISBN-13: 978-0-13-713559-2 ISBN-10: 0-13-713559-9 Text printed in the United States on recycled paper at RR Donnelley in Crawfordsville, Indiana. Third printing December 2008

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Secret Bits

How Codes Became Unbreakable

Encryption in the Hands of Terrorists, and Everyone Else

September 13, 2001. Fires were still smoldering in the wreckage of the World Trade Center when Judd Gregg of New Hampshire rose to tell the Senate what had to happen. He recalled the warnings issued by the FBI years before the country had been attacked: the FBI's most serious problem was "the encryption capability of the people who have an intention to hurt America." "It used to be," the senator went on, "that we had the capability to break most codes because of our sophistication." No more. "The technology has outstripped the code breakers," he warned. Even civil libertarian cryptographer Phil Zimmermann, whose encryption software appeared on the Internet in 1991 for use by human rights workers world-wide, agreed that the terrorists were probably encoding their messages. "I just assumed," he said, "somebody planning something so diabolical would want to hide their activities using encryption."

Encryption is the art of encoding messages so they can't be understood by eavesdroppers or adversaries into whose hands the messages might fall. De-scrambling an encrypted message requires knowing the sequence of symbols--the "key"--that was used to encrypt it. An encrypted message may be visible to the world, but without the key, it may as well be hidden in a locked box. Without the key--exactly the right key--the contents of the box, or the message, remains secret.



What was needed, Senator Gregg asserted, was "the cooperation of the community that is building the software, producing the software, and building the equipment that creates the encoding technology"--cooperation, that is, enforced by legislation. The makers of encryption software would have to enable the government to bypass the locks and retrieve the decrypted messages. And what about encryption programs written abroad, which could be shared around the world in the blink of an eye, as Zimmermann's had been? The U.S. should use "the market of the United States as leverage" in getting foreign manufacturers to follow U.S. requirements for "back doors" that could be used by the U.S. government.

By September 27, Gregg's legislation was beginning to take shape. The keys used to encrypt messages would be held in escrow by the government under tight security. There would be a "quasi-judicial entity," appointed by the Supreme Court, which would decide when law enforcement had made its case for release of the keys. Civil libertarians squawked, and doubts were raised as to whether the key escrow idea could actually work. No matter, opined the Senator in late September. "Nothing's ever perfect. If you don't try, you're never going to accomplish it. If you do try, you've at least got some opportunity for accomplishing it."

Abruptly, three weeks later, Senator Gregg dropped his legislative plan. "We are not working on an encryption bill and have no intention to," said the Senator's spokesman on October 17.

On October 24, 2001, Congress passed the USA PATRIOT Act, which gave the FBI sweeping new powers to combat terrorism. But the PATRIOT Act does not mention encryption. U.S. authorities have made no serious attempt to legislate control over cryptographic software since Gregg's proposal.

Why Not Regulate Encryption?

Throughout the 1990s, the FBI had made control of encryption its top legislative priority. Senator Gregg's proposal was a milder form of a bill, drafted by the FBI and reported out favorably by the House Select Committee on Intelligence in 1997, which would have mandated a five-year prison sentence for selling encryption products unless they enabled immediate decryption by authorized officials.

How could regulatory measures that law enforcement deemed critical in 1997 for fighting terrorism drop off the legislative agenda four years later, in the aftermath of the worst terrorist attack ever suffered by the United States of America?

No technological breakthrough in cryptography in the fall of 2001 had legislative significance. There also weren't any relevant diplomatic breakthroughs.


No other circumstances conspired to make the use of encryption by terrorists and criminals an unimportant problem. It was just that something else about encryption had become accepted as more important: the explosion of commercial transactions over the Internet. Congress suddenly realized that it had to allow banks and their customers to use encryption tools, as well as airlines and their customers, and eBay and Amazon and their customers. Anyone using the Internet for commerce needed the protection that encryption provided. Very suddenly, there were millions of such people, so many that the entire U.S. and world economy depended on public confidence in the security of electronic transactions.

The tension between enabling secure conduct of electronic commerce and preventing secret communication among outlaws had been in the air for a decade. Senator Gregg was but the last of the voices calling for restrictions on encryption. The National Research Council had issued a report of nearly 700 pages in 1996 that weighed the alternatives. The report concluded that on balance, efforts to control encryption would be ineffective, and that their costs would exceed any imaginable benefit. The intelligence and defense establishment was not persuaded. FBI Director Louis Freeh testified before Congress in 1997 that "Law enforcement is in unanimous agreement that the widespread use of robust non-key recovery [i.e., non-escrowed] encryption ultimately will devastate our ability to fight crime and prevent terrorism."

Yet only four years later, even in the face of the September 11th attack, the needs of commerce admitted no alternative to widespread dissemination of encryption software to every business in the country, as well as to every home computer from which a commercial transaction might take place. In 1997, average citizens, including elected officials, might never have bought anything online. Congress members' families might not have been regular computer users. By 2001, all that had changed--the digital explosion was happening. Computers had become consumer appliances, Internet connections were common in American homes--and awareness of electronic fraud had become widespread. Consumers did not want their credit card numbers, birthdates, and Social Security numbers exposed on the Internet.

Why is encryption so important to Internet communications that Congress was willing to risk terrorists using encryption, so that American businesses and consumers could use it too? After all, information security is not a new need. People communicating by postal mail, for example, have reasonable assurances of privacy without any use of encryption.

The answer lies in the Internet's open architecture. Bits move through the Internet not in a continuous stream, but in discrete blocks, called packets. A packet consists of about 1500 bytes, no more (see the Appendix). Data packets are not like envelopes sent through postal mail, with an address on the

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