IETF Policy on Wiretapping

Network Working Group                                               IAB
Request for Comments: 2804                                         IESG
Category: Informational                                        May 2000


                       IETF Policy on Wiretapping

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   The Internet Engineering Task Force (IETF) has been asked to take a
   position on the inclusion into IETF standards-track documents of
   functionality designed to facilitate wiretapping.

   This memo explains what the IETF thinks the question means, why its
   answer is "no", and what that answer means.

1. Summary position

   The IETF has decided not to consider requirements for wiretapping as
   part of the process for creating and maintaining IETF standards.

   It takes this position for the following basic reasons:

   - The IETF, an international standards body, believes itself to be
     the wrong forum for designing protocol or equipment features that
     address needs arising from the laws of individual countries,
     because these laws vary widely across the areas that IETF standards
     are deployed in.  Bodies whose scope of authority correspond to a
     single regime of jurisdiction are more appropriate for this task.

   - The IETF sets standards for communications that pass across
     networks that may be owned, operated and maintained by people from
     numerous jurisdictions with numerous requirements for privacy.  In
     light of these potentially divergent requirements, the IETF
     believes that the operation of the Internet and the needs of its
     users are best served by making sure the security properties of
     connections across the Internet are as well known as possible.  At
     the present stage of our ignorance this means making them as free
     from security loopholes as possible.

   - The IETF believes that in the case of traffic that is today going
     across the Internet without being protected by the end systems (by
     encryption or other means), the use of existing network features,
     if deployed intelligently, provides extensive opportunities for
     wiretapping, and should be sufficient under presently seen
     requirements for many cases. The IETF does not see an engineering
     solution that allows such wiretapping when the end systems take
     adequate measures to protect their communications.

   - The IETF believes that adding a requirement for wiretapping will
     make affected protocol designs considerably more complex.
     Experience has shown that complexity almost inevitably jeopardizes
     the security of communications even when it is not being tapped by
     any legal means; there are also obvious risks raised by having to
     protect the access to the wiretap. This is in conflict with the
     goal of freedom from security loopholes.

   - The IETF restates its strongly held belief, stated at greater
     length in [RFC 1984], that both commercial development of the
     Internet and adequate privacy for its users against illegal
     intrusion requires the wide availability of strong cryptographic
     technology.

   - On the other hand, the IETF believes that mechanisms designed to
     facilitate or enable wiretapping, or methods of using other
     facilities for such purposes, should be openly described, so as to
     ensure the maximum review of the mechanisms and ensure that they
     adhere as closely as possible to their design constraints. The IETF
     believes that the publication of such mechanisms, and the
     publication of known weaknesses in such mechanisms, is a Good
     Thing.

2. The Raven process

   The issue of the IETF doing work on legal intercept technologies came
   up as a byproduct of the extensive work that the IETF is now doing in
   the area if IP-based telephony.

   In the telephony world, there has been a tradition of cooperation
   (often mandated by law) between law enforcement agencies and
   telephone equipment operators on wiretapping, leading to companies
   that build telephone equipment adding wiretapping features to their
   telephony-related equipment, and an emerging consensus in the
   industry of how to build and manage such features. Some traditional
   telephony standards organizations have supported this by adding
   intercept features to their telephony-related standards.

   Since the future of the telephone seems to be intertwined with the
   Internet it is inevitable that the primary Internet standards
   organization would be faced with the issue sooner or later.

   In this case, some of the participants of one of the IETF working
   groups working on a new standard for communication between components
   of a distributed phone switch brought up the issue. Since adding
   features of this type would be something the IETF had never done
   before, the IETF management decided to have a public discussion
   before deciding if the working group should go ahead. A new mailing
   list was created (the Raven mailing list, see
   http://www.ietf.org/mailman/listinfo/raven) for this discussion.
   Close to 500 people subscribed to the list and about 10% of those
   sent at least one message to the list. The discussion on this list
   was a precursor to a discussion held during the IETF plenary in
   Washington, D.C.

   Twenty-nine people spoke during the plenary session. Opinions ranged
   from libertarian: 'governments have no right to wiretap' - to
   pragmatic: 'it will be done somewhere, best have it done where the
   technology was developed'. At the end of the discussion there was a
   show of hands to indicate opinions: should the IETF add special
   features, not do this or abstain. Very few people spoke out strongly
   in support for adding the intercept features, while many spoke out
   against it, but a sizable portion of the audience refused to state an
   opinion (raised their hands when asked for "abstain" in the show of
   hands).

   This is the background on the basis of which the Internet Engineering
   Steering Group (IESG) and the Internet Architecture Board (IAB) was
   asked to formulate a policy.

3. A definition of wiretapping

   The various legal statutes defining wiretapping do not give adequate
   definitions to distinguish between wiretapping and various other
   activities at the technical level. For the purposes of this memo, the
   following definition of wiretapping is used:

   Wiretapping is what occurs when information passed across the
   Internet from one party to one or more other parties is delivered to
   a third party:

   1. Without the sending party knowing about the third party

   2. Without any of the recipient parties knowing about the delivery to
      the third party

   3. When the normal expectation of the sender is that the transmitted
      information will only be seen by the recipient parties or parties
      obliged to keep the information in confidence

   4. When the third party acts deliberately to target the transmission
      of the first party, either because he is of interest, or because
      the second party's reception is of interest.

   The term "party", as used here, can refer to one person, a group of
   persons, or equipment acting on behalf of persons; the term "party"
   is used for brevity.

   Of course, many wiretaps will be bidirectional, monitoring traffic
   sent by two or more parties to each other.

   Thus, for instance, monitoring public newsgroups is not wiretapping
   (condition 3 violated), random monitoring of a large population is
   not wiretapping (condition 4 violated), a recipient passing on
   private email is not wiretapping (condition 2 violated).

   An Internet equivalent of call tracing by means of accounting logs
   (sometimes called "pen registers") that is a feature of the telephone
   network is also wiretapping by this definition, since the normal
   expectation of the sender is that the company doing the accounting
   will keep this information in confidence.

   Wiretapping may logically be thought of as 3 distinct steps:

   - Capture - getting information off the wire that contains the
     information wanted.

   - Filtering - selecting the information wanted from information
     gathered by accident.

   - Delivery - transmitting the information wanted to the ones who want
     it.

   The term applies to the whole process; for instance, random
   monitoring followed by filtering to extract information about a
   smaller group of parties would be wiretapping by this definition.

   In all these stages, the possibility of using or abusing mechanisms
   defined for this purpose for other purposes exists.

   This definition deliberately does not include considerations of:

   - Whether the wiretap is legal or not, since that is a legal, not a
     technical matter.

   - Whether the wiretap occurs in real time, or can be performed after
     the fact by looking at information recorded for other purposes
     (such as the accounting example given above).

   - What the medium targeted by the wiretap is - whether it is email,
     IP telephony, Web browsing or EDI transfers.

   These questions are believed to be irrelevant to the policy outlined
   in this memo.

   Wiretapping is also sometimes called "interception", but that term is
   also used in a sense that is considerably wider than the monitoring
   of data crossing networks, and is therefore not used here.

4. Why the IETF does not take a moral position

   Much of the debate about wiretapping has centered around the question
   of whether wiretapping is morally evil, no matter who does it,
   necessary in any civilized society, or an effective tool for catching
   criminals that has been abused in the past and will be abused again.

   The IETF has decided not to take a position in this matter, since:

   - There is no clear consensus around a single position in the IETF.

   - There is no means of detecting the morality of an act "on the
     wire".  Since the IETF deals with protocol standardization, not
     protocol deployment, it is not in a position to dictate that its
     product is only used in moral or legal ways.

   However, a few observations can be made:

   - Experience shows that tools which are effective for a purpose tend
     to be used for that purpose.

   - Experience shows that tools designed for one purpose that are
     effective for another tend to be used for that other purpose too,
     no matter what its designers intended.

   - Experience shows that if a vulnerability exists in a security
     system, it is likely that someone will take advantage of it sooner
     or later.

   - Experience shows that human factors, not technology per se, is the
     biggest single source of such vulnerabilities.

   What this boils down to is that if effective tools for wiretapping
   exist, it is likely that they will be used as designed, for purposes
   legal in their jurisdiction, and also in ways they were not intended
   for, in ways that are not legal in that jurisdiction. When weighing
   the development or deployment of such tools, this should be borne in
   mind.

5. Utility considerations

   When designing any communications function, it is a relevant question
   to ask if such functions efficiently perform the task they are
   designed for, or whether the work spent in developing them is not, in
   fact, worth the benefit gained.

   Given that there are no specific proposals being developed in the
   IETF, the IETF cannot weigh proposals for wiretapping directly in
   this manner.

   However, as above, a few general observations can be made:

   - Wiretapping by copying the bytes passed between two users of the
     Internet with known, static points of attachment is not hard.
     Standard functions designed for diagnostic purposes can accomplish
     this.

   - Correlating users' identities with their points of attachment to
     the Internet can be significantly harder, but not impossible, if
     the user uses standard means of identification. However, this means
     linking into multiple Internet subsystems used for address
     assignment, name resolution and so on; this is not trivial.

   - An adversary has several simple countermeasures available to defeat
     wiretapping attempts, even without resorting to encryption. This
     includes Internet cafes and anonymous dialups, anonymous remailers,
     multi-hop login sessions and use of obscure communications media;
     these are well known tools in the cracker community.

   - Of course, communications where the content is protected by strong
     encryption can be easily recorded, but the content is still not
     available to the wiretapper, defeating all information gathering
     apart from traffic analysis.  Since Internet data is already in
     digital form, encrypting it is very simple for the end-user.

   These things taken together mean that while wiretapping is an
   efficient tool for use in situations where the target of a wiretap is
   either ignorant or believes himself innocent of wrongdoing,
   Internet-based wiretapping is a less useful tool than might be
   imagined against an alerted and technically competent adversary.

6. Security Considerations

   Wiretapping, by definition (see above), releases information that the
   information sender did not expect to be released.

   This means that a system that allows wiretapping has to contain a
   function that can be exercised without alerting the information
   sender to the fact that his desires for privacy are not being met.

   This, in turn, means that one has to design the system in such a way
   that it cannot guarantee any level of privacy; at the maximum, it can
   only guarantee it as long as the function for wiretapping is not
   exercised.

   For instance, encrypted telephone conferences have to be designed in
   such a way that the participants cannot know to whom any shared
   keying material is being revealed.

   This means:

   - The system is less secure than it could be had this function not
     been present.

   - The system is more complex than it could be had this function not
     been present.

   - Being more complex, the risk of unintended security flaws in the
     system is larger.

   Wiretapping, even when it is not being exercised, therefore lowers
   the security of the system.

7. Acknowledgements

   This memo is endorsed by the IAB and the IESG.

   Their membership is:

   IAB:

   Harald Alvestrand
   Randall Atkinson
   Rob Austein
   Brian Carpenter
   Steve Bellovin
   Jon Crowcroft
   Steve Deering
   Ned Freed
   Tony Hain
   Tim Howes
   Geoff Huston
   John Klensin


   IESG:

   Fred Baker
   Keith Moore
   Patrik Falstrom
   Erik Nordmark
   Thomas Narten
   Randy Bush
   Bert Wijnen
   Rob Coltun
   Dave Oran
   Jeff Schiller
   Marcus Leech
   Scott Bradner
   Vern Paxson
   April Marine

   The number of contributors to the discussion are too numerous to
   list.

8. Author's Address

   This memo is authored by the IAB and the IESG.

   The chairs are:

   Fred Baker, IETF Chair
   519 Lado Drive
   Santa Barbara California 93111

   Phone: +1-408-526-4257
   EMail: fred@cisco.com


   Brian E. Carpenter, IAB Chair
   IBM
   c/o iCAIR
   Suite 150
   1890 Maple Avenue
   Evanston IL 60201
   USA

   EMail: brian@icair.org

9. References

   [RFC 1984]  IAB and IESG, "IAB and IESG Statement on Cryptographic
               Technology and the Internet", RFC 1984, August 1996.

9. Full Copyright Statement

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