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This chapter is from the book

Cryptography for Everyone

In real life, none of us is aware that we are carrying out one-way computations while we are browsing the Web. But every time we order a book from Amazon, check our bank or credit card balance, or pay for a purchase using PayPal, that is exactly what happens. The tell-tale sign that an encrypted web transaction is taking place is that the URL of the web site begins with "https" (the "s" is for "secure") instead of "http." The consumer's computer and the computer of the store or the bank negotiate the encryption, using public key cryptography—unbeknownst to the human beings involved in the transaction. The store attests to its identity by presenting a certificate signed by a Certification authority that the consumer's computer has been preconfigured to recognize. New keys are generated for each new transaction. Keys are cheap. Secret messages are everywhere on the Internet. We are all cryptographers now.

At first, public-key encryption was treated as a mathematical curiosity. Len Adleman, one of the inventors of RSA, thought that the RSA paper would be "the least interesting paper I would ever be on." Even the National Security Agency, as late as 1977, was not overly concerned about the spread of these methods. They simply did not appreciate how the personal computer revolution, just a few years away, would enable anyone with a home PC to exchange encrypted messages that even NSA could not decipher.

But as the 1980s progressed, and Internet use increased, the potential of ubiquitous cryptography began to become apparent. Intelligence agencies became increasingly concerned, and law enforcement feared that encrypted communications could put an end to government wiretapping, one of its most powerful tools. On the commercial side, industry was beginning to appreciate that customers would want private communication, especially in an era of electronic commerce. In the late 1980s and early 1990s, the Bush and the Clinton administrations were floating proposals to control the spread of cryptographic systems.

In 1994, the Clinton administration unveiled a plan for an "Escrowed Encryption Standard" that would be used on telephones that provided encrypted communications. The technology, dubbed "Clipper," was an encryption chip developed by the NSA that included a back door—an extra key held by the government, which would let law enforcement and intelligence agencies decrypt the phone communications. According to the proposal, the government would purchase only Clipper phones for secure communication. Anyone wanting to do business with the government over a secure telephone would also have to use a Clipper phone. Industry reception was cold, however (see Figure 5.8), and the plan was dropped. But in a sequence of modified proposals beginning in 1995, the White House attempted to convince industry to create encryption products that had similar back doors. The carrot here, and the stick, was export control law. Under U.S. law, cryptographic products could not be exported without a license, and violating export controls could result in severe criminal penalties. The administration proposed that encryption software would receive export licenses only if it contained back doors.

From "Clipper Wars," the furious industry reaction against the Clinton Administration's "Clipper Chip" proposal. Reprinted with permission.

Figure 5.8

Figure 5.8 Part of the "crypto wars," the furious industry reaction against the Clinton Administration's "Clipper chip" proposal.

The ensuing, often heated negotiations, sometimes referred to as the "crypto wars," played out over the remainder of the 1990s. Law enforcement and national security argued the need for encryption controls. On the other side of the debate were the technology companies, who did not want government regulation, and civil liberties groups, who warned against the potential for growing communication surveillance. In essence, policymakers could not come to grips with the transformation of a major military technology into an everyday personal tool.

We met Phil Zimmermann at the beginning of this chapter, and his career now becomes a central part of the story. Zimmermann was a journeyman programmer and civil libertarian who had been interested in cryptography since his youth. He had read a Scientific American column about RSA encryption in 1977, but did not have access to the kinds of computers that would be needed to implement arithmetic on huge integers, as the RSA algorithms demanded. But computers will get powerful enough if you wait. As the 1980s progressed, it became possible to implement RSA on home computers. Zimmermann set about to produce encryption software for the people, to counter the threat of increased government surveillance. As he later testified before Congress:

  • The power of computers had shifted the balance towards ease of surveillance. In the past, if the government wanted to violate the privacy of ordinary citizens, it had to expend a certain amount of effort to intercept and steam open and read paper mail, or listen to and possibly transcribe spoken telephone conversations. This is analogous to catching fish with a hook and a line, one fish at a time. Fortunately for freedom and democracy, this kind of labor-intensive monitoring is not practical on a large scale. Today, electronic mail is gradually replacing conventional paper mail, and is soon to be the norm for everyone, not the novelty it is today. Unlike paper mail, e-mail messages are just too easy to intercept and scan for interesting keywords. This can be done easily, routinely, automatically, and undetectable on a grand scale. This is analogous to driftnet fishing—making a quantitative and qualitative Orwellian difference to the health of democracy.

Cryptography was the answer. If governments were to have unlimited surveillance powers over electronic communications, people everywhere needed easy-to-use, cheap, uncrackable cryptography so they could communicate without governments being able to understand them.

Zimmermann faced obstacles that would have stopped less-zealous souls. RSA was a patented invention. MIT had licensed it exclusively to the RSA Data Security Company, which produced commercial encryption software for corporations, and RSA Data Security had no interest in granting Zimmermann the license he would need to distribute his RSA code freely, as he wished to do.

And there was government policy, which was, of course, exactly the problem to which Zimmermann felt his encryption software was the solution. On January 24, 1991, Senator Joseph Biden, a co-sponsor of antiterrorist legislation Senate Bill 266, inserted some new language into the bill:

  • It is the sense of Congress that providers of electronic communications services and manufacturers of electronic communications service equipment shall ensure that communications systems permit the government to obtain the plaintext contents of voice, data, and other communications when appropriate authorized by law.

This language received a furious reaction from civil liberties groups and wound up not surviving, but Zimmermann decided to take matters into his own hands.

By June of 1991, Zimmermann had completed a working version of his software. He named it PGP for "Pretty Good Privacy," after Ralph's mythical Pretty Good Groceries that sponsored Garrison Keillor's Prairie Home Companion. The software mysteriously appeared on several U.S. computers, available for anyone in the world to download. Soon copies were everywhere—not just in the U.S., but all over the world. In Zimmermann's own words: "This technology belongs to everybody." The genie was out of the bottle and was not going back in.

Zimmermann paid a price for his libertarian gesture. First, RSA Data Security was confident that this technology belonged to it, not to "everybody." The company was enraged that its patented technology was being given away. Second, the government was furious. It instituted a criminal investigation for violation of the export control laws, although it was not clear what laws, if any, Zimmermann had violated. Eventually MIT brokered an agreement that let Zimmermann use the RSA patent, and devised a way to put PGP on the Internet for use in the U.S., and in conformance with export controls.

By the end of the decade, the progress of electronic commerce had overtaken the key escrow debate, and the government had ended its criminal investigation without an indictment. Zimmermann built a business around PGP (see www.pgp.com), while still allowing free downloads for individuals. His web site contains testimonials from human rights groups in Eastern Europe and Guatemala attesting to the liberating force of secret communication among individuals and agencies working against oppressive regimes. Zimmermann had won.

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