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(a)acm.org
