Testimony of Philip Zimmermann to Subcommittee for Economic Policy, Trade, and the Environment US House of Representatives 12 Oct 1993 Mr. Chairman and members of the committee, my name is Philip Zimmermann, and I am a software engineer who specializes in cryptography and data security. I'm here to talk to you today about the need to change US export control policy for cryptographic software. I want to thank you for the opportunity to be here and commend you for your attention to this important issue. I am the author of PGP (Pretty Good Privacy), a public-key encryption software package for the protection of electronic mail. Since PGP was published domestically as freeware in June of 1991, it has spread organically all over the world and has since become the de facto worldwide standard for encryption of E-mail. The US Customs Service is investigating how PGP spread outside the US. Because I am a target of this ongoing criminal investigation, my lawyer has advised me not to answer any questions related to the investigation. I. The information age is here. Computers were developed in secret back in World War II mainly to break codes. Ordinary people did not have access to computers, because they were few in number and too expensive. Some people postulated that there would never be a need for more than half a dozen computers in the country. Governments formed their attitudes toward cryptographic technology during this period. And these attitudes persist today. Why would ordinary people need to have access to good cryptography? Another problem with cryptography in those days was that cryptographic keys had to be distributed over secure channels so that both parties could send encrypted traffic over insecure channels. Governments solved that problem by dispatching key couriers with satchels handcuffed to their wrists. Governments could afford to send guys like these to their embassies overseas. But the great masses of ordinary people would never have access to practical cryptography if keys had to be distributed this way. No matter how cheap and powerful personal computers might someday become, you just can't send the keys electronically without the risk of interception. This widened the feasibility gap between Government and personal access to cryptography. Today, we live in a new world that has had two major breakthroughs that have an impact on this state of affairs. The first is the coming of the personal computer and the information age. The second breakthrough is public-key cryptography. With the first breakthrough comes cheap ubiquitous personal computers, modems, FAX machines, the Internet, E-mail, digital cellular phones, personal digital assistants (PDAs), wireless digital networks, ISDN, cable TV, and the data superhighway. This information revolution is catalyzing the emergence of a global economy. But this renaissance in electronic digital communication brings with it a disturbing erosion of our privacy. 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, and listen to and possibly transcribe spoken telephone conversation. 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 is 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 undetectably on a grand scale. This is analogous to driftnet fishing-- making a quantitative and qualitative Orwellian difference to the health of democracy. The second breakthrough came in the late 1970s, with the mathematics of public key cryptography. This allows people to communicate securely and conveniently with people they've never met, with no prior exchange of keys over secure channels. No more special key couriers with black bags. This, coupled with the trappings of the information age, means the great masses of people can at last use cryptography. This new technology also provides digital signatures to authenticate transactions and messages, and allows for digital money, with all the implications that has for an electronic digital economy. (See appendix) This convergence of technology-- cheap ubiquitous PCs, modems, FAX, digital phones, information superhighways, et cetera-- is all part of the information revolution. Encryption is just simple arithmetic to all this digital hardware. All these devices will be using encryption. The rest of the world uses it, and they laugh at the US because we are railing against nature, trying to stop it. Trying to stop this is like trying to legislate the tides and the weather. It's like the buggy whip manufacturers trying to stop the cars-- even with the NSA on their side, it's still impossible. The information revolution is good for democracy-- good for a free market and trade. It contributed to the fall of the Soviet empire. They couldn't stop it either. Soon, every off-the-shelf multimedia PC will become a secure voice telephone, through the use of freely available software. What does this mean for the Government's Clipper chip and key escrow systems? Like every new technology, this comes at some cost. Cars pollute the air. Cryptography can help criminals hide their activities. People in the law enforcement and intelligence communities are going to look at this only in their own terms. But even with these costs, we still can't stop this from happening in a free market global economy. Most people I talk to outside of Government feel that the net result of providing privacy will be positive. President Clinton is fond of saying that we should "make change our friend". These sweeping technological changes have big implications, but are unstoppable. Are we going to make change our friend? Or are we going to criminalize cryptography? Are we going to incarcerate our honest, well-intentioned software engineers? Law enforcement and intelligence interests in the Government have attempted many times to suppress the availability of strong domestic encryption technology. The most recent examples are Senate Bill 266 which mandated back doors in crypto systems, the FBI Digital Telephony bill, and the Clipper chip key escrow initiative. All of these have met with strong opposition from industry and civil liberties groups. It is impossible to obtain real privacy in the information age without good cryptography. The Clinton Administration has made it a major policy priority to help build the National Information Infrastructure (NII). Yet, some elements of the Government seems intent on deploying and entrenching a communications infrastructure that would deny the citizenry the ability to protect its privacy. This is unsettling because in a democracy, it is possible for bad people to occasionally get elected-- sometimes very bad people. Normally, a well-functioning democracy has ways to remove these people from power. But the wrong technology infrastructure could allow such a future government to watch every move anyone makes to oppose it. It could very well be the last government we ever elect. When making public policy decisions about new technologies for the Government, I think one should ask oneself which technologies would best strengthen the hand of a police state. Then, do not allow the Government to deploy those technologies. This is simply a matter of good civic hygiene. II. Export controls are outdated and are a threat to privacy and economic competitivness. The current export control regime makes no sense anymore, given advances in technology. There has been considerable debate about allowing the export of implementations of the full 56-bit Data Encryption Standard (DES). At a recent academic cryptography conference, Michael Wiener of Bell Northern Research in Ottawa presented a paper on how to crack the DES with a special machine. He has fully designed and tested a chip that guesses DES keys at high speed until it finds the right one. Although he has refrained from building the real chips so far, he can get these chips manufactured for $10.50 each, and can build 57000 of them into a special machine for $1 million that can try every DES key in 7 hours, averaging a solution in 3.5 hours. $1 million can be hidden in the budget of many companies. For $10 million, it takes 21 minutes to crack, and for $100 million, just two minutes. That's full 56-bit DES, cracked in just two minutes. I'm sure the NSA can do it in seconds, with their budget. This means that DES is now effectively dead for purposes of serious data security applications. If Congress acts now to enable the export of full DES products, it will be a day late and a dollar short. If a Boeing executive who carries his notebook computer to the Paris airshow wants to use PGP to send email to his home office in Seattle, are we helping American competitivness by arguing that he has even potentially committed a federal crime? Knowledge of cryptography is becoming so widespread, that export controls are no longer effective at controlling the spread of this technology. People everywhere can and do write good cryptographic software, and we import it here but cannot export it, to the detriment of our indigenous software industry. I wrote PGP from information in the open literature, putting it into a convenient package that everyone can use in a desktop or palmtop computer. Then I gave it away for free, for the good of our democracy. This could have popped up anywhere, and spread. Other people could have and would have done it. And are doing it. Again and again. All over the planet. This technology belongs to everybody. III. People want their privacy very badly. PGP has spread like a prairie fire, fanned by countless people who fervently want their privacy restored in the information age. Today, human rights organizations are using PGP to protect their people overseas. Amnesty International uses it. The human rights group in the American Association for the Advancement of Science uses it. Some Americans don't understand why I should be this concerned about the power of Government. But talking to people in Eastern Europe, you don't have to explain it to them. They already get it-- and they don't understand why we don't. I want to read you a quote from some E-mail I got last week from someone in Latvia, on the day that Boris Yeltsin was going to war with his Parliament: "Phil I wish you to know: let it never be, but if dictatorship takes over Russia your PGP is widespread from Baltic to Far East now and will help democratic people if necessary. Thanks." Appendix -- How Public-Key Cryptography Works --------------------------------------------- In conventional cryptosystems, such as the US Federal Data Encryption Standard (DES), a single key is used for both encryption and decryption. This means that a key must be initially transmitted via secure channels so that both parties have it before encrypted messages can be sent over insecure channels. This may be inconvenient. If you have a secure channel for exchanging keys, then why do you need cryptography in the first place? In public key cryptosystems, everyone has two related complementary keys, a publicly revealed key and a secret key. Each key unlocks the code that the other key makes. Knowing the public key does not help you deduce the corresponding secret key. The public key can be published and widely disseminated across a communications network. This protocol provides privacy without the need for the same kind of secure channels that a conventional cryptosystem requires. Anyone can use a recipient's public key to encrypt a message to that person, and that recipient uses her own corresponding secret key to decrypt that message. No one but the recipient can decrypt it, because no one else has access to that secret key. Not even the person who encrypted the message can decrypt it. Message authentication is also provided. The sender's own secret key can be used to encrypt a message, thereby "signing" it. This creates a digital signature of a message, which the recipient (or anyone else) can check by using the sender's public key to decrypt it. This proves that the sender was the true originator of the message, and that the message has not been subsequently altered by anyone else, because the sender alone possesses the secret key that made that signature. Forgery of a signed message is infeasible, and the sender cannot later disavow his signature. These two processes can be combined to provide both privacy and authentication by first signing a message with your own secret key, then encrypting the signed message with the recipient's public key. The recipient reverses these steps by first decrypting the message with her own secret key, then checking the enclosed signature with your public key. These steps are done automatically by the recipient's software. -- Philip Zimmermann 3021 11th Street Boulder, Colorado 80304 303 541-0140 E-mail: prz@acm.org