To Tap or Not to Tap
                           Dorothy E. Denning
                            December 1, 1992

Under current law in the U.S., the government is authorized to
intercept the wire, electronic, or oral communications of a criminal
subject upon obtaining a special court order which has been designed by
Congress and approved by the Supreme Court.  When served with a court
order, service providers and operators are obligated under statute to
assist in the execution of a court-authorized tap or microphone
installation.  To obtain this order, Congress and the Supreme Court
have specified that law enforcement must demonstrate that there is
probable cause to believe that the subject under investigation is
committing some specific, serious felony and that communications
concerning the offense will be obtained through the intercepts.  Before
issuing a court order, a judge must review a lengthy affidavit that
sets forth all the evidence and agree with the assertions contained
therein.  The affidavit must also demonstrate that other investigative
techniques have been tried without success, that they won't work, or
that they would be too dangerous.  In the decade from 1982-1991, state
and federal agencies conducted 7,467 taps, which have thus far led to
19,259 convictions.  Convictions resulting from interceptions conducted
in the last few years are still accumulating, as trials regarding those
subjects are held.

The ability of law enforcement to draw upon this investigative tool is
now at risk.  Methods that have been used to intercept analogue voice
communications carried over copper wires do not work with many of the
new digital-based technologies and services such as ISDN (Integrated
Services Digital Network), fiber optic transmissions, and the
increasing number of mobile telecommunication networks and
architectures.  Although it is technically feasible to intercept
digital communications, not all systems have been designed or equipped
to meet the intercept requirements of law enforcement.  According to
the FBI, numerous court orders have not been sought, executed, or fully
carried out because of technological problems.  To address these
problems, the Department of Justice is seeking Digital Telephony
legislation that would require the service providers and operators to
meet their statutory assistance requirements by maintaining the
capability to intercept particular communications so as to permit law
enforcement to perform its monitoring function at a remote government
monitoring facility in real time.

The proposed legislation has stimulated a lively debate.  Much of the
debate has focused on concerns that the proposal, if enacted, could
hold back technology, jeopardize security and privacy, make U.S.
products non-competitive, burden the country with unjustifiable and
unnecessary costs, and ultimately fail to meet the stated objectives if
criminals encrypt their communications.

This article presents the case for the proposed Digital Telephony
legislation and responds to the above concerns.  Although the Digital
Telephony proposal does not address encryption, the possibility of
regulating cryptography will be discussed following the section on the
proposed legislation.


To ensure law enforcement's continued ability to conduct
court-authorized taps, the Administration, at the request of the
Department of Justice and the FBI, proposed Digital Telephony
legislation [11].  The version submitted to Congress in September 1992
would require providers of electronic communications services and
private branch exchange (PBX) operators to ensure that the government's
ability to lawfully intercept communications is not curtailed or
prevented entirely by the introduction of advanced technology.  Service
providers would be responsible for providing the government, in real
time, the communication signals of the individual(s) named in a court
order such that the signals could be transferred to a remote government
monitoring facility, without detection by the subject, and without
degradation of service.  Providers of services within the public
switched network would be given 18 months to comply and PBX operators 3
years.  The Attorney General would have the authority to grant
exceptions and waivers and seek civil penalties and injunctive relief
to enforce the provisions.  A fine of up to $10,000 a day could be
levied for non-compliance.  Government systems would be exempt on the
grounds that law enforcement has the necessary cooperation to access
the premises.  The proposal is strongly supported as a critical public
safety measure by state and local law enforcement (who conduct the
majority of wiretaps), the National Association of Attorney Generals,
the National Association of District Attorneys, and numerous law
enforcement associations.

Although the proposed legislation does not expand the authority of the
government to lawfully acquire the contents of communications, it
arguably places greater constraints and demands on service providers
and operators.  The current law (Title 18, United States Code, Section
2518(4)) states that service providers are required to furnish the
responsible law enforcement official with all information, facilities,
and technical assistance necessary to perform the intercept
unobtrusively and with a minimum of interference.  It does not say
explicitly that the providers must build and use systems that ensure
timely interception is possible.  This is not surprising since the
emerging technological advances and attendant difficulties would not
have been anticipated in 1968 when the legislation was enacted, but it
leaves open to interpretation the meaning of the word "assist" and the
exact requirements placed on service providers and operators in today's
digital world.

When the FBI first encountered the intercept problems, they attempted
to educate the telecommunications industry concerning the problems.
They sought voluntary cooperation and a commitment to address the
problems.  But after meeting with industry officials for more than two
years, they concluded that industry was not committed to resolving the
problems without a mandate and that legislation was necessary to
clarify the responsibilities of service providers and operators, to
ensure that all providers and operators comply, and to provide a
mechanism whereby industry could justify the development costs.
Legislation would ensure that all service providers remain on the same
competitive "level playing field."

The proposed Digital Telephony legislation was not introduced in the
last (1992) session of Congress because time ran out.  Meanwhile, the
FBI is continuing its discussions with industry through two technical
committees, one with representatives from the telecommunications
industry, the other with representatives from the computer industry,
and many companies are working hard to meet law enforcement's needs.

The next subsections address major concerns that have been expressed by
some computer scientists, civil libertarians, and people in the
telecommunications industry.  Many of these concerns are articulated in
a white paper [2] issued by the Electronic Frontier Foundation (EFF) on
behalf of an ad- hoc coalition of representatives from industry and
public interest groups, including ATT, IBM, and ACLU.

Technology Advancement

     Concern 1: The proposal would hold back technology and stymie

Some people are concerned that requiring technology modifications to
support taps would prevent full use of new technologies.  Janlori
Goldman of the ACLU has called this a "dumbing down" and stated that
"if the government wants to engage in surveillance, it must bear the
burden of keeping pace with new developments" [3].

I see no technological reason why any of the new technologies,
including digital technologies, cannot support an intercept
capability.  In many cases the intercept capability would likely
parallel or draw upon the maintenance and security features used by the
telephone companies to ensure their systems are functioning properly
and are not abused.  At the very least, the intercept capability can be
programmed into the switches where the bit stream for a connection must
be isolated anyway so that it can be routed to its correct destination
(for interception, a duplicate copy of the bit stream can be routed to
a remote government monitoring facility).  But whereas this
modification would be relatively straightforward for the service
providers to make, it would be impossible for the government to do on
their own since they lack access to the switches.  Also, because of the
complexities of switches and switch software, the government has no
desire to engage in self help and interject itself into the arena of
networks or central office switching and thereby perhaps inadvertently
disrupt service on a widespread basis.

Another reason for not asking the government to implement their own
surveillance mechanisms is that the providers can do so surgically, and
hence less intrusively.  For example, where ISDN or bundled fibre optic
transmissions are involved, service providers can isolate an individual
communications channel, whereas the government might have to intercept
everything travelling over a line or link supporting simultaneous
transmission of multiple, commingled communications in order to extract
the desired channel.  The FBI has stated that law enforcement does not
want access to the communications of anyone outside the ambit of the
court order.

In short, the Digital Telephony proposal would not require the
communications industry to "dumb down" technology; rather, it would
require industry to use technology to make networks "smarter."

Security and Privacy

     Concern 2: Providing an intercept capability would jeopardize
     security and privacy, first because the remote monitoring
     capability would make the systems vulnerable to attack, and second
     because the intercept capability itself would introduce a new
     vulnerability into the systems.

The first part of this concern relating to the remote monitoring
capability seems to have arisen from a misinterpretation of the
requirement for remote monitoring.  Sec. 2. (1) of the proposed bill
states that "Providers of electronic communication services and private
branch exchange operators shall provide ... the capacity for the government
to intercept wire and electronic communications when authorized
by law: ... (4) at a government monitoring facility remote from the
target facility and remote from the system of the electronic
communication services provider or private branch exchange operator."
Some people have mistakenly interpreted this as a requirement for law
enforcement to be able to electronically, and independently, enter a
computer switch from a remote location to initiate a tap.  If this were
the case, then an unauthorized person might be able to come in through
the connection and tap into a line.  The FBI has made it clear,
however, that they are not asking for the capability to initiate taps
in this fashion, but rather for a tap initiated by the service provider
to be routed to a pre- defined remote location over a leased line.  In
the specification of the requirements for the government monitoring
facility, the proposal states: "Normally, the government leases a line
from the electronic communication services provider's or private branch
exchange operator's switch to another location owned or operated by the
government. ... The legislation does not establish any independent
'dial-up' authority by which criminal law enforcement agencies could
effectuate interceptions without the affirmative assistance of the
providers or operators.  The providers and operators will continue to
make the necessary interconnections or issue the necessary switch
program instructions to effectuate an interception."  Indeed, the
requirement set forth in the legislation memorializes longstanding
practice and procedure.  Since the connection to a remote government
monitoring facility would support an outgoing data stream only, it
could not be used to break into a switch and, therefore, does not
impose any new or additional danger to the security of the systems and
the privacy of the people who rely on them for their communications.

This misinterpretation of the remote monitoring requirement also led to
a concern that law enforcement would abuse the wiretapping capability
and surreptitiously perform unauthorized taps.  Because the only people
who would have access to the systems for activating a tap would be
employees of the service providers, who have been strict about
requiring court orders, the possibility of law enforcement performing
unauthorized taps seems even less likely than with present technology.

The second part of the concern, that the intercept capability itself
could introduce a new vulnerability, is at least potentially more
serious.  If the intercept capability is programmed into the switches
and an unauthorized person can break into a switch, then that person
might be able to eavesdrop on a line or find out if a particular line
is being tapped.  Indeed, "hackers" have broken into poorly protected
computer switches and eavesdropped on lines.  But the switches can and
must be designed and operated to prevent such breakins independent of
any intercept capabilities.  Security is essential not only to protect
against unlawful eavesdropping but to ensure reliable service and
protect against other types of abuses.  The Administration, the
Department of Justice, and the FBI all are strong advocates for
security in telecommunications networks.

To protect against possible abuses by employees of the service
providers, access to the software for activating an intercept should be
minimized and well-protected through appropriate authentication
mechanisms and access controls.  The intercept control software might
be left off the system and installed in an isolated partition only when
needed prior to executing an authorized tap.  With newer, advanced
technology and proper overall security measures, it should be possible
to provide greater protection against abuse than is presently


     Concern 3: Implementing the intercept requirements could harm the
     competitiveness of U.S.  products in the global market.

This concern, which arose in conjunction with the preceding concerns
about holding back technology and security, is based on an assumption
that it would take U.S. companies longer to bring their products to
market, and other countries would not want to buy products that
increased the vulnerability of their systems.  However, because the
products can be designed to operate with a high level of security and
because other governments (many of which run or oversee their nation's
telecommunications networks) might desire similar features in their
telecommunications systems, the Digital Telephony proposal would be
competition neutral.  In fact, several other countries have expressed
an interest in obtaining such products.  U.S. companies could have a
competitive advantage if they take the lead now, and indeed might be at
a disadvantage if they fail to act and companies outside the U.S. do.
Under the proposed legislation, foreign communications companies would
have to comply with the U.S. law and standards if they seek to provide
service in the U.S., thereby preventing any unfair competition in this

Cost and Benefits

     Concern 4: The cost could be enormous and is not obviously
     justifiable by the perceived benefits.

The cost of compliance is a major concern.  The existing law states
that the service providers and operators shall be compensated for
"expenses" incurred in assisting with a tap.  The proposed law leaves
open who would bear the capital expenses of modifications and
engineering costs required to maintain the intercept capability.

The FBI, in consultation with industry, has estimated the cumulative
costs for a switched-based software solution to be in the range
$150-$250 million, and the maximum development costs to be $300 million
or approximately 1.5% of the telecommunications industry's yearly
acquisition budget of $22 billion [11].  However, these costs are
highly speculative and actual costs could be considerably lower if the
service providers pursue a combination non-switch/switch-based
solution.  In addition, whatever the costs, they likely would be
amortized over several years.  Some people have suggested that the
government should pay the costs, but a privately funded approach is
more likely to encourage market forces to bring forth the most
cost-effective solutions.  In either case, this is a societal cost that
will be paid for one way or the other by the citizenry to ensure
effective law enforcement and the public safety.

The benefits that derive from the use of electronic surveillance are
difficult to quantify.  Because wiretapping has been used infrequently
(less than 1000 taps per year), some people have argued that it is not
essential   that the crimes could be solved by other means that would
be less costly.  But by law, wiretapping can only be used when normal
investigative procedures have been tried and have failed or when they
appear unlikely to succeed or too dangerous.  Also, according to the
FBI, many serous crimes can only be solved or prevented by electronic

According to the FBI, electronic surveillance has been essential in
preventing serious and often violent criminal activities including
Organized Crime, drug trafficking, extortion, terrorism, kidnaping, and
murder.  While the benefits to society of preventing such crimes and
saving human lives are incalculable, the economic benefits alone are
estimated to be billions of dollars per year [11].  During the period
1985-1991, court-ordered electronic surveillance conducted just by the
FBI led to 7,324 convictions, almost $300 million in fines being
levied, over $750 million in recoveries, restitutions, and
court-ordered forfeitures, and close to $2 billion in prevented
potential economic loss.  Since the FBI conducts fewer than one-third
of all intercepts, the total benefits derived from electronic
surveillance by all law enforcement agencies is considerably higher.

One area where electronic surveillance has played a major role is in
combatting Organized Crime.  In 1986, the President's Commission on
Organized Crime estimated that organized crime reduces the output of
the U.S. economy by $18.2 billion a year (1986 dollars), costs workers
414,000 jobs, raises consumer prices by 0.3%, and lowers per capita
personal income by $77.22 (1986 dollars) [6].  Although the impact of
law enforcement's successful investigations of Organized Crime on these
losses has not been thoroughly studied, in 1988, David Williams of the
Office of Special Investigations, General Accounting Office, testified
before U.S. Senate hearings on organized crime that "Evidence gathered
through electronic surveillance... has had a devastating impact on
organized crime."  According to the FBI, the hierarchy of Organized
Crime has been neutralized or destabilized through the use of
electronic surveillance, and thirty odd years of successes would be
reversed if the ability to conduct court-authorized electronic
surveillance was lost.

Almost two thirds of all court orders for electronic surveillance are
used to fight the war on drugs, and electronic surveillance has been
critical in identifying and then dismantling major drug trafficking
organizations.  Although the benefits of these operations are difficult
to quantify, their impact on the economy and people's lives is
potentially enormous.  In 1988, the Public Health Service estimated the
health, labor, and crime costs of drug abuse at $58.3 billion [7].  The
FBI estimates that the war on drugs and its continuing legacy of
violent street crime in the form of near daily drive-by murders would
be substantially, if not totally, lost if law enforcement were to lose
its capability for electronic surveillance.

Electronic surveillance has been used to investigate aggravated
governmental fraud and corruption.  A recent military-procurement fraud
case ("Ill-Wind") involving persons in the Department of Defense and
defense contractors has so far led to 59 convictions and nearly $250
million in fines, restitutions, and recoveries ordered.

The use of electronic surveillance has successfully prevented several
terrorist attacks, including the bombing of a foreign consulate in the
U.S., a rocket attack against a U.S. ally, and the acquisition of a
surface-to-air missile that was to be used in an act that likely would
have led to numerous deaths.  By intercepting voice, fax, and
communications on a local bulletin board system, the FBI prevented the
proposed kidnaping and murder of young child for the purpose of making
a "snuff murder" film.  Wiretapping also has been used to obtain
evidence against "hackers" who broke into computer systems.  This case
illustrates how wiretapping, which is popularly regarded as an
anti-privacy tool, actually helps protect the privacy and proprietary
interests of law-abiding citizens by helping to convict those who
violate those interests.

Aside from preventing and solving serious crime, wiretapping yields
evidence that is considerably more reliable than that obtained by many
other methods such as informants, and is less dangerous for law
enforcement officials than breaking and entering to install bugs in
homes or offices.  It is critical in those situations where the crime
leaders are not present at the places where the illegal transactions
take place, as is the case with major drug cartels directed by distant
drug chieftains.

The societal and economic benefits of authorized electronic
surveillance will increase as telecommunication services and facilities
continue to expand and electronic commerce comes into widespread use,
bringing with it more possibilities for fraud and other types of

Some people are troubled that the citizens would have to pay for the
wiretapping capability, possibly through their phone bills.  In an open
letter to several Congressional committees, Joseph Truitt wrote:  "What
an insult   to be forced to pay for the privilege of being tapped!"
[9]  However, through tax revenues and telephone company security
office budgets, law enforcement has always been able to carry out
investigations and conduct electronic surveillance, and unless a person
is subject of a court order, that person will not be paying to be
intercepted.  As citizens, we have always paid for law enforcement,
knowing fully well that it will be used against us if we ever engage in
criminal activities.  This is one of the costs of protecting society
from people who do not respect the laws.  One could equally say: "What
an insult    to be forced to pay for the privilege of being arrested!"


     Concern 5.  It is unclear who must comply with the proposed
     legislation and what compliance means.

The EFF expressed a concern that the proposal was overly broad,
covering "just about everyone" including businesses, universities, and
other organizations owning local and wide area networks; providers of
electronic mail and information services such as Prodigy and
Compuserve; operators of networks such as the Internet; and owners of
computer bulletin boards [2].  They raised questions about the
conditions under which exemptions might be granted and the requirements
for compliance.  An earlier report published by the General Accounting
Office [10] also asked for greater clarity about what is meant by full
compliance, for example, response time for executing a court order.

In response, the FBI points out that the existing legislation already
imposes an assistance obligation upon electronic communication service
providers which includes all of the foregoing named service entities,
and that the reason the requirements are stated in generic terms is
because historically these have sufficed and law enforcement's
requirements, including those for a timely response, have been met.
With respect to exemptions, the proposed legislation states that the
Attorney General may grant exemptions for whole classes of systems
where no serious criminal activity is likely to take place, for
example, hospital telephone systems, and grant waivers for providers
and operators who cannot comply or need additional time.  The FBI has
also indicated that interceptions would normally be sought at a point
close to the target, such that intra-network interceptions would be
very infrequent generally, and that information networks such as
Compuserve and Prodigy would likely be considered for exemption.
Although the proposed legislation allows for stiff fines, the
legislative history background materials state that "this provision is
not expected to be used."


It is now possible to purchase at reasonable cost a telephone security
device that encrypts communications and to acquire software that
encrypts data transmitted over computer networks.  Even if law
enforcement retains its capability to intercept communications, this
capability ultimately could be diminished if criminals begin to hide
their communications through encryption and law enforcement is unable
to obtain access to the "plaintext" or unscrambled communications.  If
encryption becomes cheap and ubiquitous, this could pose a serious
threat to effective law enforcement and hence to the public's safety.

The Digital Telephony proposal does not address encryption, leaving
open the question of how best to deal with it.  Currently, the use of
cryptography in this country is unregulated, though export of the
technology is regulated.  Cryptography is regulated in some of the
major European countries.

This section explores the possibility of regulating cryptography use.
For an introduction to cryptography and the methods referenced here,
see for example, my book [1].

Possible Approaches

In order to assess whether cryptography can or should be regulated, we
need some idea of how it might be done.  Our knowledge of available
options is quite limited, however, since the possibility of regulating
cryptography in the U.S. has thus far received little public
discussion.  The following three possibilities are offered as a
starting point for discussion:

     1.   Weak cryptography
     2.   Escrowed private keys
     3.   Direct access to session keys

Weak Cryptography

This approach would require that cryptographic systems be sufficiently
weak that the government could break them, preferably in real time
since timeliness is crucial for preventing many crimes such as murder
and terrorist attacks.  While weak cryptography would offer adequate
protection against most eavesdropping when the consequences of
disclosure are not particularly damaging, it could be unacceptable in
many contexts such as protecting corporate communications that are
seriously threatened by industrial espionage.

It is worth noting, however, that the general migration from analog to
digital communications itself provides a high level of protection in
the area of telecommunications, since such communications are only
understandable with the aid of very sophisticated technology unlike the
relative ease with which eavesdroppers can understand analog
intercepts.  Thus, it is not obvious that most individuals and
organizations would either need or demand strong encryption, especially
since most do not use any form of encryption at present.  However,
history shows that methods which are secure today may be blown apart
tomorrow, so this may not be a dependable long-term solution.

Escrowed Private Keys

Ron Rivest has proposed using high-security encryption with "escrowed
secret keys" [8].  Each user would be required to register his or her
secret key with an independent trustee, and cryptographic products
would be designed to operate only with keys that are certified as being
properly escrowed.  The trustee could be some neutral entity such as
the U.S. Postal Service, a bank, or the clerks of the Federal Courts.
It would be extremely difficult to subvert the system since someone
would need the cooperation of the telecommunications provider (to get
the communication stream) and the trustee (to get the key), both of
which would require a court order.

Additional protection can be obtained by distributing the power of the
trustee.  For example, two trustees could be used, and the keys could
be stored with the first trustee encrypted under a key known only to
the second.  Alternatively, using Silvio Micali's "fair public-key
cryptography," each user's private key could be split into, say, five
pieces, and each piece given to a different trustee [4].  The splitting
is done in such a way that all five pieces are required to reconstruct
the original key, but each one can be independently verified, and the
set of five can be verified as a whole without putting them all

In order to implement an approach based on escrowed keys, methods would
be needed for registering and changing keys that belong to individuals
and organizations and for gaining access to the transient "session
keys" that are used to encrypt actual communications.  Key registration
might be incorporated into the sale and licensing of cryptographic
products.  To facilitate law enforcement's access to session keys, the
protocols used to distribute or negotiate session keys during the start
of a communications could be standardized.  Once law enforcement has
acquired the private keys on a given line, they would then be able to
acquire the session keys by intercepting the key initialization

One drawback to this approach is the overhead and bureaucracy
associated with key registration.  Another is that it is limited to
cryptographic systems that require more-or-less permanent private
keys.  Although some such as the RSA public-key cryptosystem fit this
description, others do not.

Direct Access to Session Keys

Ultimately a session key is needed to decrypt a communications stream,
and this approach would give the service provider direct access to the
session key when an intercept has been established in response to a
court order.  The service provider can then make the session key
available to law enforcement along with the communications stream.

One way of making the session key available to the provider is for the
provider to participate in the protocol used to set up the key.  For
example, the following three-way extension of the Diffie- Hellman
public-key distribution protocol could be used to establish a session
key that would be known only to the two communicants and the service
provider:  Each party independently generates a random exponent x and
computes y = g^x mod p for a given g and prime p.  All three parties
then pass their value of y to the right (imagine they are in a
circle).  Next, using the received value of y, they compute z = y^x mod p
and pass it to the right.  Finally, using the received value of z,
they compute the shared session key  k = z^x mod p, which will be the
value g raised to all three exponents.  An eavesdropper, who sees only
the values of y and z, cannot compute k because he or she will lack the
requisite exponent.

If a court order has been issued and an intercept activated, the
component or module operating on behalf of the service provider would
pass the key on to the remote government monitoring facility before
destroying it.  Obviously, this component would have to be designed
with great care in order to make sure that keys are not improperly
disclosed and that they are immediately destroyed when no intercept has
been activated.

This approach has the advantage over the preceding ones of allowing the
use of a strong cryptosystem while not requiring the use and
registration of permanent keys.  It has the disadvantage of requiring
the service provider to be brought into the loop during the key
negotiation protocol, which might also be difficult or costly to

The cost of regulating the use of cryptography following either of
these last two approaches is unknown.  A feasibility study would be
needed to examine the requirements in greater detail and estimate the

Protecting Privacy and Proprietary Interests

The last two approaches suggest that it is possible to regulate
cryptography without compromising the privacy and proprietary interests
of the citizens.  Some people have argued, however, that the citizens
have a right to absolute communications secrecy from everyone,
including the government, under all circumstances, and that requiring
people to make the plaintext of their encrypted communications
available to the government directly or indirectly would be tantamount
to forbidding them from having a private conversation in a secret place
or using an obscure foreign language, or to making them carry a
microphone.  These absolutist positions, however, contort the concept
of privacy and do not represent valid analogies.

Our laws, as embodied in the Constitution and Bill of Rights, common
law, tort law, and legislation, reflect a "social contract" that
strikes a balance between our rights to privacy and to an orderly
society.  This contract does not grant us absolute privacy in all
areas.  For example, whereas we are protected against unreasonable
searches and seizures by the Fourth Amendment, we are not immune from
searches and seizures when there is probable cause we have committed a
crime and a judge has issued a warrant.  When Congress enacted
wiretapping legislation and the Supreme Court ruled that wiretapping
with a warrant was permitted, law enforcement was empowered to
intercept communications, whether they were encrypted or not.  Now that
encryption is becoming an issue, it would seem appropriate for Congress
to set an encryption policy.

Viewed narrowly, cryptography offers the possibility for absolute
communications protection or privacy that is not available to us in any
other area of our lives.  Our physical beings are constantly at risk,
and our premises, cars, safes, and lockers can be illegally broken into
or lawfully searched.  We live with this risk and indeed benefit from
it whenever we lock ourselves out of our homes, cars, and so forth.  It
is unclear that we need an absolute level of protection or privacy for
our communications that surpasses that in every other areas of our
lives.  Indeed, our speech in many regards and areas is already subject
to balanced regulation (e.g., slander, libel, obscenity, falsely
yelling "fire" in a theater).

Although illegal eavesdropping poses a threat to corporate security,
the communications network is not the weak link.  Employees and former
employees have posed a bigger threat.  If companies themselves do not
regulate cryptography, their employees would have a means of
transmitting company secrets outside the company with impunity and
without detection.  The military-procurement fraud case mentioned
earlier was solved only because law enforcement was able to tap the
communications of a Pentagon employee.  Thus, corporate security is not
necessarily best served by an encryption system that offers absolute
secrecy to its employees.


Some people have argued that regulating cryptography in this country
would harm the competitiveness of U.S. products overseas.  No other
country would want to buy products based on weak encryption algorithms
or with built-in mechanisms for registering private keys or making
session keys available to the service providers.

Like the basic intercept capability issue, it is not only conceivable
but likely that other countries will be interested in products that
allow their governments to decrypt communications when authorized by
law.  Foreign governments, for example, would be loathe to see
terrorists operate and communicate in their country with impunity
behind the shield of absolutely secure cryptographic devices.  U.S.
companies could take the lead in developing products that meet the
security needs of customers and the legitimate needs of law enforcement
and governments abroad.

Enforcing Cryptography Regulation

Many people have voiced a concern that criminals would violate
cryptography regulations and use cryptosystems that the government
could not decrypt, thereby also obtaining an absolute privacy beyond
that of law-abiding citizens.  This is typically expressed as "if
encryption is outlawed, only outlaws will have encryption."  Because
products are being designed, sold, and given away in the absence of any
regulation, this outcome is indeed possible.

Cryptography can be embedded in a device such as a "secure phone" or
security device attached to a standard phone that encrypts
communications transmitted between phones (or fax machines), or it can
be embedded in software packages or modules that run on computers and
encrypt the communications transmitted over computer networks.  It
seems easier to regulate and control telephone encryption devices than
software.  For example, if an approach based on escrowed keys is
adopted, then the keys that are embedded in the products could be given
to one or more trustees at the time of sale, and the products could be
designed so that the keys could not be changed without bringing the
product in for service or negotiating a new key with a trustee online.
Similarly, if an approach based on direct access to session keys is
adopted, a suitable key negotiation protocol could be built into the
products.  Although criminals could develop their own non-compliant
products, it is likely that most criminals would use commercial
off-the-shelf products rather than developing their own.

Software encryption, performed on personal computers or servers, could
be much more difficult to regulate, especially since strong
cryptographic methods have been distributed through networks such as
the Internet and cryptographic algorithms can be implemented by any
competent programmer.  But enforcing cryptography regulations on
software may be less critical for law enforcement since electronic
surveillance has typically focused on telephone calls or
conversations.  Thus, it would be a mistake to make the difficulty of
controlling software encryption an excuse for not regulating

Although it would be practically impossible to prevent the use of
non-compliant products, the work factor required to acquire and use
these products may be sufficiently high to deter their use.  But even
if they are used, if there is probable cause that a person is involved
with some serious crime and a warrant is issued for that person's
communications, then legislation could also provide grounds for
arresting that person if he or she violated the laws governing
cryptography as a separate offense.  However, it would be important to
not lose sight of the purpose of cryptography regulation and to not
expend resources enforcing it for its own sake.

If private encryption is allowed to proceed without some reasonable
accommodation, it will logically lead to situations where someone is
arrested outright when probable cause for a criminal act is
demonstrated.  This could lead to premature cessation of investigations
where critical evidence would not be obtained.


Granger Morgan has observed that the controversy over the proposed
Digital Telephony legislation is symbolic of a broader set of conflicts
arising from several competing national interests: individual privacy,
security for organizations, effective domestic law enforcement,
effective international intelligence gathering, and secure world-wide
reliable communications [5]. Because the balance between these becomes
hard wired into the design of our telecommunications system, it is
difficult to adjust the balance in response to changing world
conditions and changing values.  Technology has been drifting in a
direction that could shift the balance away from effective law
enforcement and intelligence gathering toward absolute individual
privacy and corporate security.  Since the consequences of doing so
would pose a serious threat to society, I am not content to let this
happen without careful consideration and public discussion.

With respect to wiretapping, we can take the steps necessary to ensure
law enforcement's continued ability to intercept and interpret
electronic communications when authorized by court order, or let this
capability gradually fade away as new technologies are deployed and
cryptographic products become widely available.  The consequence of
this choice will affect our personal safety, our right to live in a
society where lawlessness is not tolerated, and the ability of law
enforcement to prevent serious and often violent criminal activity.

While the societal and economic benefits that would come from the
proposed Digital Telephony legislation are difficult to quantify, the
economic benefits of maintaining effective law enforcement through its
capability of conducting authorized intercepts are estimated to be in
the billions and many lives would likely be saved.  These benefits are
likely to increase with the growth in telecommunications.  By
comparison, the cumulative costs of complying with the proposed Digital
Telephony legislation are roughly estimated to be in the range $150-250
million.  Although the benefits might not be fully realized if the
intercept capability would, as has been suggested, thwart technological
progress, compromise security and privacy, or harm competitiveness,
these are unlikely outcomes as discussed in the preceding sections.
Indeed, effective law enforcement is crucial for protecting the privacy
of law abiding citizens and the business interests of companies.

If we fail to enact legislation that will ensure a continued capability
for court-ordered electronic surveillance, we cannot be guaranteed that
all service providers will provide this capability voluntarily.
Systems fielded without an adequate provision for court-ordered
intercepts would become sanctuaries for criminality wherein Organized
Crime leaders, drug dealers, terrorists, and other criminals could
conspire and act with impunity.  Eventually, we could find ourselves
with an increase in major crimes against society, a greatly diminished
capacity to fight them, and no timely solution.

Less is known about the implications of regulating cryptography since
no specific legislative or other proposal has been seriously
considered.  Although government regulation of cryptography may be
somewhat cumbersome and subject to evasion, we should give it full
consideration.  Regulated encryption would provide considerably greater
security and privacy than no encryption, which has been the norm for
most personal and corporate communications.  We must balance our
competing interests in a way that ensures effective law enforcement and
intelligence gathering, while protecting individual privacy and
corporate security.


I am deeply grateful to the following people for providing constructive
comments on earlier versions of this article, for helpful discussions,
and for their willingness to debate those points they disagreed with:
William A. Bayse, Kier Boyd, Julia Dederer, Peter Denning, Jack
Edwards, Carl Ellison, Mike Godwin, Lance Hoffman, Phil Karn, Bruce
Koball, Steve Lipner, Alan McDonald, Donn Parker, Ron Rivest, Marc
Rotenberg, Jeff Smith, James Sylvester, and Willis Ware.


1.   Denning, Dorothy E., Cryptography and Data Security, Addison-Wesley,

2.   Electronic Frontier Foundation, "Analysis of the FBI Proposal Regarding
     Digital Telephony," Sept. 17, 1992.

3.   Goldman, Janlori, "Why Cater to Luddites," The Washington Times, May 24,

4.   Micali, Silvio, "Fair Public-Key Cryptosystems," Laboratory for Computer
     Science, MIT, August 21, 1992.

5.   Morgan, M. Granger, "Viewpoint," The Institute, IEEE, Nov. 1992.

6.   President's Commision on Organized Crime, "The Impact: Organized Crime
     Today," 1986.

7.   Rice, D. et al., "The Economic Cost of Alcohol and Drug Abuse and Mental
     Illness: 1985," U.S. Dept. of Health and Human Services, Table 1, page 2,

8.   Rivest, Ronald L., "Response to NIST's Proposal," Comm. ACM, Vol. 35,
     No. 7, July 1992, pp. 41-47.

9.   Truitt, Joseph, Open letter of Sept. 17, 1992 to congress protesting
     proposed FBI Digital Telephony bill, Computer Privacy Digest, Vol. 1,
     Issue 081, Sept. 23, 1992.

10.  Unites States General Accounting Office, "FBI Advanced Communications
     Technologies Pose Wiretapping Challenges," Briefing Report to the
     Chairman, Subcommittee on Telecommunications and Finance, Committee
     on Energy and Commerce, House of Representatives, GAO/IMTEC-92-68BR,
     July 1992.

11.  United States Department of Justice, Federal Bureau of Investigation,
     "Digital Telephony," 1992.

Advanced TSCM Signals Detection and Analysis
TSCM - Sweeping the Spectrum for Eavesdropping Devices

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