Telecom/1996-04-telecom-walnutcreek.iso/legal-fcc/whit.diffie-clipper.test

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Subject: Whit Diffie Testimony - Senate Clipper Hearing, May 3, 1994

Too large for a regular issue of the Digest, passed along FYI.

PAT

  From: Monty Solomon <[e-mail]>
  Subject: Whit Diffie testimony - Senate Clipper Hearing, May 3 1994

  From: [e-mail] (Stanton McCandlish)
  Newsgroups: comp.org.eff.news
  Subject: Whit Diffie testimony - Senate Clipper Hearing, May 3 1994

  Forwarded message:
  From: [e-mail]
  Date: Fri,  6 May 1994 at 08h04

        Key Escrow: Its Impact and Alternatives

                            Testimony of
            Dr. Whitfield Diffie
            Distinguished Engineer
            Sun Microsystems, Inc.

           Before the Subcommitee on Technology and the Law
                  of the Senate Judiciary Committee

                            3 May 1994

Dr. Diffie is also testifying on behalf of the Digital Privacy and
Security Working Group, a group of more than 50 computer, communica-
tions and public interest organizations and associations working on
communications privacy issues.

                 ------------------------

 I would like to begin by expressing my thanks to the chairman, the
members of the committee, and the committee staff for the chance not
only of appearing before this committee, but of appearing in such
distinguished company.  It is a pleasure to be able to present not
only my own concerns and those of Sun Microsystem, but to have the
opportunity of representing the Digital Privacy and Security Working
Group.

    I think it is also appropriate to say a few words about my
experience in the field of communication security.  I first began
thinking about cryptography while working at Stanford University in
the late summer of 1972.  This subsequently brought me into contact
with Professor Martin E. Hellman of the Electrical Engineering
Department.  Marty and I worked together throughout the mid-1970s and
discovered the family of techniques now known as public key
cryptography.  It is these techniques that are directly responsible
for the issue before the committee today.  Prior to public key
cryptography, any large scale cryptographically secure system required
trusted elements with the fundamental capability of decrypting any
message protected by the system.  Public key cryptography eliminated
the need for network subscribers to place this level of trust in any
network element.  In so doing, it potentially reduced the subscribers'
vulnerability to government wiretapping.  It is this vulnerability
that the Escrowed Encryption Initiative, seeks to reintroduce.

    In 1978, I walked through the revolving door from academia to
industry and for a dozen years was `Manager of Secure Systems
Research' at Northern Telecom.  In 1991, I took my present position
with Sun Microsystems.  This has allowed me an inside look at the
problems of communication security from the viewpoints of both the
telecommunications and computer industries.

        The Key Escrow Program

    Just over a year ago, the Administration revealed plans for a
program of key escrow technology best known by the name of its
flagship product the Clipper chip.  The program's objective is to
promote the use of cryptographic equipment incorporating a special
back door or trap door mechanism that will permit the Federal
Government to decrypt communications without the knowledge or consent
of the communicating parties when it considers this necessary for law
enforcement or intelligence purposes.  In effect, the privacy of these
communications will be placed in escrow with the Federal Government.

    The committee has asked me to address myself to this proposal and
in particular to consider three issues:

      o Problems with key escrow, particularly in the area of privacy.

      o The impact of the key escrow proposal on American business
    both at home and abroad.

      o Alternatives to key escrow.

            Scope

    In the course of discussing the key escrow program over the past
year, I have often encountered a piecemeal viewpoint that seeks to
take each individual program at face value and treat it independently
of the others.  I believe, on the contrary, that it is appropriate to
take a broad view of the issues.  The problem confronting us is to
assess the advisability of key escrow and its impact on our society.
This requires examining the effect of private, commercial, and
possibly criminal use of cryptography and the advisability and effect
of the use of communications intelligence techniques by law
enforcement.  In doing this, I will attempt to avoid becoming bogged
down in the distinctions between the Escrowed Encryption Standard
(FIPS185) with its orientation toward telephone communications and the
CAPSTONE/TESSERA/MOSAIC program with its orientation toward computer
networks.  I will treat these, together with the Proposed Digital
Signature Standard and to a lesser extent the Digital Telephony
Proposal, as a unified whole whose objective is to maintain and expand
electronic interception for both law enforcement and national security
purposes.

        Privacy Problems of Key Escrow

    When the First Amendment became part of our constitution in 1791,
speech took place in the streets, the market, the fields, the office,
the bar room, the bedroom, etc.  It could be used to express intimacy,
conduct business, or discuss politics and it must have been recognized
that privacy was an indispensable component of the character of many
of these conversations.  It seems that the right --- in the case of
some expressions of intimacy even the obligation --- of the
participants to take measures to guarantee the privacy of their
conversations can hardly have been in doubt, despite the fact that the
right to speak privately could be abused in the service of crime.

    Today, telephone conversations stand on an equal footing with the
venues available in the past.  In particular, a lot of political
speech --- from friends discussing how to vote to candidates planning
strategy with their aides --- occurs over the phone.  And, of all the
forms of speech protected by the first amendment, political speech is
foremost.  The legitimacy of the laws in a democracy grows out of the
democratic process.  Unless the people are free to discuss the issues
--- and privacy is an essential component of many of these discussions
--- that process cannot take place.

    There has been a very important change in two hundred years,
however.  In the seventeen-nineties two ordinary people could achieve
a high degree of security in conversation merely by the exercise of a
little prudence and common sense.  Giving the ordinary person
comparable access to privacy in the normal actions of the world today
requires the ready availability of complex technical equipment.  It
has been thoughtlessly said, in discussions of cryptographic policy,
that cryptography brings the unprecedented promise of absolute
privacy.  In fact, it only goes a short way to make up for the loss of
an assurance of privacy that can never be regained.

    As is widely noted, there is a fundamental similarity between the
power of the government to intercept communications and its ability to
search premises.  Recognizing this power, the fourth amendment places
controls on the government's power of search and similar controls have
been placed by law on the use of wiretaps.  There is, however, no
suggestion in the fourth amendment of a guarantee that the government
will find what it seeks in a search.  Just as people have been free to
to protect the things they considered private, by hiding them or
storing them with friends, they have been free to protect their
conversations from being overheard.

    The ill ease that most people feel in contemplating police use of
wiretaps is rooted in awareness of the abuses to which wiretapping can
be put.  Unlike a search, it is so unintrusive as to be invisible to
its victim and this inherently undermines accountability. Totalitarian
regimes have given us abundant evidence that the use of wiretaps and
even the fear of their use can stifle free speech.  Nor is the
political use of electronic surveillance a strictly foreign problem.
We have precedent in contemporary American history for its use by the
party in power in its attempts to stay in power?

    The essence of the key escrow program is an attempt use the buying
power and export control authority of government to promote standards
that will deny ordinary people ready options for true protection of
their conversations.  In a world where more and more communication
take place between people who frequently can not meet face to face,
this is a dangerous course of action.

    The objections raised so far apply to the principle of key escrow.
Objections can also be raised to details of the present proposal.
These deal with the secrecy of the algorithm, the impact on security
of the escrow mechanism, and the way in which the proposal has been
put into effect.

        Secrecy of the SKIPJACK Algorithm

    An objection that has been raised to the current key escrow
proposal is that the cryptographic algorithm used in the Clipper Chip
is secret and is not available for public scrutiny.  One counter to
this objection is that the users of cryptographic equipment are
neither qualified to evaluate the quality of the algorithm nor, with
rare exceptions, interested in attempting the task.  In a fundamental
way, these objections miss the point.

    Within the national security establishment, responsibility for
communication security is well understood.  It rests with NSA.  In
industry, the responsibility is far more diffuse.  Individual users
are not typically concerned with the functioning of pieces of
equipment.  They acquire trust through a complex social web comprising
standards, corporate security officers, professional societies, etc.
A classified standard foisted on the civilian sector will have only
one element of this process, Federal endorsement.

    One consequence of the use of a classified algoritym that is of
particular concern to industry is the fact that the algorithm is only
available in tamper resistant hardware.  Software is one of the most
flexible and economical ways of building products known.  In typical
computer engineering practice, the additional expense of implementing
functions in hardware is only undertaken when the speed of software in
not adequate for the task.  Often in these cases, more expensive,
higher performance, hardware implementations interoperate with less
expensive, lower performance versions.  Having a standard that can
only be implemented in hardware will increase costs and damage
interoperability.

    Security Problems with Key Escrow

    From the viewpoint of a user, any key escrow system diminishes
security.  It puts potential for access to the user's communications
in the hands of an escrow agent who's intentions, policies, security
capabilities, and future cannot be entirely known.  In the context of
modern secure telephone systems, the contrast between escrowed and
unescrowed communications is particularly stark.  In the process of
setting up a secure call, modern secure telephones manufacture
cryptographic keys that will be used for the protection of one and
only one call and will be erased after the call is complete.  Public
key cryptography has made it possible to do this in such a way that
these keys, once erased, can never be recovered.  This give the users
a degree of privacy similar to that in a face to face meeting.  The
effect of key escrow is much like having a tape recorder on throughout
the meeting.  Even if the tapes are very carefully protected, the
people whose words they hold can never be certain that they will not
someday be played to a much wider audience.

    There are also specific vulnerabilities associated with the
present proposal.

    The Skipjack algorithm uses 80-bit keys.  If it is as good as NSA
claims, cryptanalyzing it will require searching through all these
keys or doing about a million billion billion encryptions.  This makes
it sixteen million times as hard to break as DES.  A telephone
conversation would have to be valuable indeed to justify the expense
of such a computation and it is quite plausible that this is entirely
infeasible today.

    The problem is that in creating the Law Enforcement Access Field,
or LEAF that implements key escrow, the Clipper chip also uses 80-bit
keys.  This means that in order to be able to decode everything ever
encrypted by a Clipper chip it is only necessary to do a little more
than twice as much work as would be required to read any one message
--- one cryptanalysis to recover a Session Key followed by one to
recover the Device Unique Key.  A third cryptanalysis is needed to
obtain the Family Key, but this need be done only once, since it is
the same in all chips.

    The process is conceptually straightforward.

     1. Starting with a set of messages encrypted with a particular
    Clipper chip cryptanalyze the LEAF fields, by trying every
    key, until a key is found that produces a well formed
    plaintext from every LEAF.  This works because the LEAF
    specifically includes an authenticator designed to make well
    formed LEAFs recognizable.  Once the Family Key has been found
    it can be used in attacking any Clipper Chip and this process
    need not be repeated.

     2. Pick a message and decrypt its LEAF with the family key.
    Eighty bits of the result form a cryptogram whose plaintext
    is the Session Key used to encrypt the message.  Decrypt
    this field with every key in turn.  Try decrypting the message
    with each resulting 80-bit quantity to see if it is the
    correct session key.  When the correct session key is discovered,
    the key that produced it will be the correct Device Unique
    Key.

     3. The combination of the Family Key and the Device Unique Key
    can now be used to read any message ever encrypted by
    the Clipper chip under attack.

    It might be argued that the scenario described above requires
knowing the SKIPJACK algorithm and the LEAF creation method, both of
which are classified.  It is an article of faith, however, in
communications security that nothing that stays constant for a long
period of time can be counted on to remain secret.  With the passage
of time, the chances that the chips will be reverse engineered
increases.

Irregularities in Adoption of the Standard

    Finally, there are disturbing aspects to the development of the
key escrow FIPS.  Under the Computer Security Act of 1987,
responsibility for security of civilian communications rests with the
National Institute of Standards and Technology.  Pursuant to this
statute, the Escrowed Encryption Standard appeared as Federal
Information Processing Standard 185, under the auspices of the
Commerce Department.  Apparently, however, authority over the secret
technology underlying the standard and the documents embodying this
technology, continues to reside with NSA.  We thus have a curious
arrangement in which a Department of Commerce standard seems to be
under the effective control of a Department of Defense agency.  This
appears to violate at least the spirit of the Computer Security Act
and strain beyond credibility its provisions for NIST's making use of
NSA's expertise.

            Impact on Business

    Business today is characterized by an unprecedented freedom and
volume of travel by both people and goods.  Ease of communication,
both physical and electronic, has ushered in an era of international
markets and multinational corporations.  No country is large enough
that its industries can concentrate on the domestic market to the
exclusion of all others.  When foreign sales rival or exceed domestic
ones, the structure of the corporation follows suit with new divisions
placed in proximity to markets, materials, or labor.

    Security of electronic communication is as essential in this
environment as security of transportation and storage have been to
businesses throughout history.  The communication system must ensure
that orders for goods and services are genuine, guarantee that
payments are credited to the proper accounts, and protect the privacy
of business plans and personal information.

    Two new factors are making security both more essential and more
difficult to achieve.  The first is the rise in importance of
intellectual property.  Since much of what is now bought and sold is
information varying from computer programs to surveys of customer
buying habits, information security has become an end in itself rather
than just a means for ensuring the security of people and property.
The second is the rising demand for mobility in communications.
Traveling corporate computer users sit down at workstations they have
never seen before and expect the same environment that is on the desks
in their offices.  They carry cellular telephones and communicate
constantly by radio.  They haul out portable PCs and dial their home
computers from locations around the globe.  With each such action they
expose their information to threats of eavesdropping and falsification
barely known a decade ago.

    Because this information economy is relentlessly global, no nation
can successfully isolate itself from international competition.  The
communication systems we build will have to be interoperable with
those of other nations.  A standard based on a secret American
technology and designed to give American intelligence access to the
communications it protects seems an unlikely candidate for widespread
acceptance.  If we are to maintain our leading position in the
information market places, we much give our full support to the
development of open international security standards that protect the
interests of all parties fairly.

        Potential for Excessive Regulation

    The key escrow program also presents the specter of increased
regulation of the design and production of new computer and
communications products.  FIPS185 states that `Approved implementations
may be procured by authorized organizations for integration into
security equipment.'  This raises the question of what organizations
will be authorized and what requirements will be placed upon them?  Is
it likely that people prepared to require that surveillance be built
into communication switches would shrink from requiring that equipment
make pre-encryption difficult as a condition for getting `approved
implementations'?  Such requirements have been imposed as conditions
of export approval for security equipment.  Should industry's need to
acquire tamper resistant parts force it to submit to such requirements,
key escrow will usher in an era of unprecedented regulation of American
development and manufacturing.

        Alternatives to Key Escrow

    It is impossible to address the issue of alternatives to key
escrow, without asking whether there is a problem, what the problem is
and what solution, if any, the problem requires.

    In recent testimony before this committee, the FBI has portrayed
communications interception as an indispensable tool of police work
and complained that the utility of this tool is threatened by
developments in modern communications.  This testimony, however, uses
the broader term `electronic surveillance' almost exclusively and
appears to include some cases in which the electronic surveillance
consisted of bugs rather than wiretaps.  Although the FBI testimony
speaks of numerous of convictions, it names not a single defendant,
court, case, or docket number.  This imprecision makes adequate study
of the testimony impossible and leaves open two issues: the
effectiveness of communications interception in particular and that of
electronic surveillance in general.

    On balance, it appears more likely that the investigative and
evidential utility of wiretaps is rising than that it is falling.
This is partly because criminals, like law abiding citizens, do more
talking on the phone these days.  It is partly because modern
communication systems, like ISDN, provide much more information about
each call, revealing where it came from in real time even when it
originated a long way away.  This detailed information about who
called whom, when, and for how long, that modern switches provide,
improves the PEN register and trap and trace techniques that police
use to map the extent of criminal conspiracies.  It is unaffected by
any encryption that the callers may apply.

    With respect to other kinds of electronic surveillance, the
picture for law enforcement looks even brighter.  Miniaturization of
electronics and improvements in digital signal processing are making
bugs smaller, improving their fidelity, making them harder to detect,
and making them more reliable.  Forms of electronic surveillance for
which no warrant is held to be necessary, particularly TV cameras in
public places, have become widespread.  This creates a base of
information that was, for example, used in two distinct ways in the
Tylenol poisoning case of the mid-1980s.

    Broadening the consideration of high tech crime fighting tools to
include vehicle tracking, DNA fingerprinting, individual recognition
by infrared tracing of the veins in the face, and database profiling,
makes it seem unlikely that the failures of law enforcement are due
to the inadequacy of its technical tools.

    If we turn our attention to foreign intelligence, we see a similar
picture.  Communications intelligence today is enjoying a golden age.
The steady migration of communications from older, less accessible,
media, both physical and electronic, has been the dominant factor.
The loss of information resulting from improvements in security has
been consistently outweighed by the increased volume and quality of
information available.  As a result, the communications intelligence
product has been improving for more than fifty years, with no end in
sight.  The rising importance of telecommunications in the life of
industrialized countries coupled with the rising importance of
wireless communications, can be expected to give rise to an
intelligence bonanza in the decades to come.

    Mobile communication is one of the fastest growing areas of the
telecommunications industry and the advantages of cellular phones,
wireless local area networks, and direct satellite communication
systems are such that they are often installed even in applications
where mobility is not required.  Satellite communications are in
extensive use, particularly in equatorial regions and cellular
telephone systems are being widely deployed in rural areas throughout
the world in preference to undertaking the substantial expense of
subscriber access wiring.

    New technologies are also opening up new possibilities.  Advances
in emitter identification, network penetration techniques, and the
implementation of cryptanalytic or crypto-diagnostic operations within
intercept equipment are likely to provide more new sources of
intelligence than are lost as a result of commercial use of
cryptography.

    It should also be noted that changing circumstances change
appropriate behavior.  Although intelligence continues to play a vital
role in the post cold war world, the techniques that were appropriate
against an opponent capable of destroying the United States within
hours may not be appropriate against merely economic rivals.

    If, however, that we accept that some measure of control over
the deployment of cryptography is needed, we must distinguish two
cases:

    The use of cryptography to protect communications, and

    The use of cryptography to protect stored information.


It is good security practice in protecting communications to keep any
keys that can be used to decipher the communications for as short a
time as possible.  Discoveries in cryptography in the past two decades
have made it possible to have secure telephones in which the keys last
only for the duration of the call and can never be recreated,
thereafter.  A key escrow proposal surrenders this advantage by
creating a new set of escrowed keys that are stored indefinitely and
can always be used to read earlier traffic.

    With regard to protection of stored information, the situation is
quite different.  The keys for decrypting information in storage must
be kept for the entire lifetime of the stored information; if they are
lost, the information is lost.  An individual might consider encrypting
files and trusting the keys to memory, but no organization of any size
could risk the bulk of its files in this fashion.  Some form of key
archiving, backup, or escrow is thus inherent in the use of
cryptography for storage.  Such procedured will guarantee that
encrypted files on disks are accessible to subpoena in much the same
way that file on paper are today.

    Many business communications, such as electronic funds transfers,
fall into an intermediate category.  Although the primary purpose is
communication rather than storage, the transactions are of a formal
nature.  In these cases, an escrow mechanism much like those in
current commercial use may be appropriate.  In a high value
transaction, where the buyer and seller do not have an established
business relationship, either party may demand the use of a mutually
trusted escrow agent who will take temporary custody of both the goods
and the payment.  In a similar fashion, either party to an encrypted
transaction might demand that only keys escrowed with a mutually
acceptable escrow agent be used.

    What is most important here is that the laws, customs, and
practices governing electronic commerce and, in a broader context,
electronic society are just beginning to develop.  It is likely that
escrow mechanisms will be among the tools employed.  It is, however,
too early to say what form they should take.  They will need to be
worked out as society gets more experience with the new communications
media.  They should not be imposed by government before society's real
needs have been determined.

        Conduct of the Key Escrow Initiative

    In my experience, the people who support the key escrow initiative
are inclined to express substantial trust in the government.  I find
it ironic therefore that in its conduct of this program, the administration
has followed a course that could hardly have been better designed to
provoke distrust.  The introduction of mechanisms designed to assure
the governments ability to conduct electronic surveillance on its
citizens and limit the ability of the citizens to protect themselves
against such surveillance is a major policy desision of the
information age.  It has been presented, however, as a technicality,
buried in an obscure series of regulations.  In so doing, it has
avoided congressional consideration of either its objectives or its
budget.  The underlying secrecy of the technology has been used as a
tool for doleing out information piecemeal and making a timely
understanding of the issues difficult to achieve.

        Suppose We Make a Mistake

    In closing, I would like to ask a question.  Suppose we make a
mistake?

      o Suppose we fail to adopt a key excrow system and later
    decide that one is needed?

      o Suppose we adopt a key escrow system now when none is
    needed?

Which would be the more serious error?

    It is generally accepted that rights are not absolute.  If private
access to high-grade encryption presented a clear and present danger
to society, there would be little political opposition to controlling
it.  The reason there is so much disagreement is that there is so
little evidence of a problem.

    If allowing or even encouraging wide dissemination of high-grade
cryptography proves to be a mistake, it will be a correctable mistake.
Generations of electronic equipment follow one another very quickly.
If cryptography comes to present such a problem that there is popular
consensus for regulating it, this will be just as possible in a decade
as it is today.  If on the other hand, we set the precedent of
building government surveillance capabilities into our security
equipment we risk entrenching a bureaucracy that will not easily
surrender the power this gives.

            Recommendation

    In light of these considerations, I would like to suggest that the
Federal Standards making process should be brought back into line with
the intent of the Computer Security Act of 1987.  Congres should press
the National Institute of Standards and Technology, with the cooperation
of the National Security Agency, to declassify the SKIPJACK algorithm
and issue a revised version of FIPS 185 that specifies the algorithm
and omits the key escrow provisions.  This would be a proper replacement
for FIPS 46, the Data Encryption Standard, and would serve the needs
of the U.S. Government, U.S.  industry, and U.S.  citizens for years
to come.

                Notes

    I have examined some aspects of the subjects treated here at
greater length in other testimony and comments and copies of these
have been made available to the committee.

"The Impact of Regulating Cryptography on the Computer and
Communications Industries" Testimony Before the House Subcommittee on
Telecommunications and Finance, 9 June 1993.


"The Impact of a Secret Cryptographic Standard on Encryption,
Privacy, Law Enforcement and Technology" Testimony Before the House
Subcommittee on Science and Technology, 11 May 1993

Letter to the director of the Computer Systems Laboratory at the
National Institute of Standards and Technology, commenting on the
proposed Escrowed Encryption Standard, 27 September 1993.