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Versions: 00 01 02 draft-irtf-hrpc-anonymity

Human Rights Protocol Considerations Research Group        S. Bortzmeyer
Internet-Draft                                                     AFNIC
Intended status: Informational                              N. ten Oever
Expires: August 13, 2018                                      ARTICLE 19
                                                       February 09, 2018

             Anonymity, Human Rights and Internet Protocols


   Anonymity is less discussed in the IETF than for instance security
   [RFC3552] or privacy [RFC6973].  This can be attributed to the fact
   anonymity is a hard technical problem or that anonymizing user data
   is not of specific market interest.  It remains a fact that 'most
   internet users would like to be anonymous online at least
   occasionally' [Pew].

   This document aims to break down the different meanings and
   implications of anonymity on a mediated computer network.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on August 13, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Vocabulary Used . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Should protocols promote anonymity? . . . . . . . . . . . . .   4
   4.  Example of use cases  . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Simultaneous use  . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Successive use  . . . . . . . . . . . . . . . . . . . . .   5
     4.3.  TODO  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Practical advices . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Protocol developers . . . . . . . . . . . . . . . . . . .   5
     5.2.  Protocol implementors . . . . . . . . . . . . . . . . . .   6
   6.  Open Questions  . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   9.  Research Group Information  . . . . . . . . . . . . . . . . .   7
   10. Objections against anonymity  . . . . . . . . . . . . . . . .   7
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     11.1.  Informative References . . . . . . . . . . . . . . . . .   8
     11.2.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   There seems to be a clear need for anonymity online in an environment
   where harassment on the Internet is on the increase [Pew2] and the UN
   Special Rapporteur for Freedom of Expression calls anonymity
   'necessary for the exercise of the right to freedom of opinion and
   expression in the digital age' [UNHRC2015].

   Nonetheless anonymity is not getting much discussion at the IETF,
   providing anonymity does not seem a (semi-)objective for many
   protocols, even though several documents contribute to improving
   anonymity such as [RFC7258], [RFC7626], [RFC7858].

   There are initiatives on the Internet to improve end users anonymity,
   most notably [torproject], but these initiatives rely on adding
   encryption in the application layer.

   This document aims to break down the different meanings and
   implications of anonymity on a mediated computer network and to see

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   whether (some parts of) anonymity should be taken into consideration
   in protocol development.

2.  Vocabulary Used

   Concepts in this draft currently strongly hinges on [AnonTerm]

   Anonymity  A state of an individual in which an observer or attacker
      cannot identify the individual within a set of other individuals
      (the anonymity set).  [RFC6973]

   Linkability  Linkability of two or more items of interest (IOIs -
      Items Of Interest, e.g., subjects, messages, actions, ...) from an
      attacker's perspective means that within the system (comprising
      these and possibly other items), the attacker can sufficiently
      distinguish whether these IOIs are related or not.  [AnonTerm]

   Pseudonymity  Derived from pseudonym, a persistent identity which is
      not the same as the entity's given (or official) name.  For all
      IETF protocols, pseudonimity is a given: protocols don't care
      whether the identity is an official one or not.  Even if the
      protocol allows to use ifficial identities (for instance in the
      From: header of an Internet email), it dos not require it.  But it
      should be noted that, if the user cannot create new pseudonyms
      easily, pseudonyms suffer from linkability.  Unlikability depends
      on this ability to create new pseudonyms gratis and at will (good
      examples are SSH keys or Bitcoin addresses).

   Unlinkability  Unlinkability of two or more items of interest (IOIs,
      e.g., subjects, messages, actions, ...) from an attacker's
      perspective means that within the system (comprising these and
      possibly other items), the attacker cannot sufficiently
      distinguish whether these IOIs are related or not.  [AnonTerm]

   Undetectability  The impossibility of being noticed or discovered

      Undetectability of an item of interest (IOI) from an attacker's
      perspective means that the attacker cannot sufficiently
      distinguish whether it exists or not [AnonTerm]


      Unobservability of an item of interest (IOI) means:
      undetectability of the IOI against all subjects uninvolved in it

      anonymity of the subject(s) involved in the IOI even against the
      other subject(s) involved in that IOI.  [AnonTerm]

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   It should be noted that the word "anonymity" is both very loaded
   politically (witness all the headlines about the "darknet") and
   poorly understood.  Most texts talking about anonymity actually refer
   to pseudonymity (for instance, when people say that "Bitcoin is
   anonymous").  This confusion is even in the example given in
   [RFC4949] definition of anonymity.

   Anonymity is strongly linked to unlinkability: if your actions are
   linkable, it suffices that one of them is tied to your identity, and
   anonymity is over.

   It should be noted that anonymity is not binary: there have been
   these recent years a lot of progress of desanonymisation techniques
   (see also [GDPR], article 26).  Data is never fully "anonymous", it
   is only more or less anonymous.  [RFC6235] [MITdeano] [Utexas]

3.  Should protocols promote anonymity?

   The amount of data that is generated by and about individuals is
   growing exponentially.  This can be attributed to the fact that an
   ever increasing number of actions is digitally mediated, and the
   increase of connected sensors in the every day environment.  Even
   though these two causes do not fully fall within the scope of the
   IETF, there is a significant part of these two examples that do.

   TODO add here more examples of the need to anonymity

   With the increase of data there is also an increasing ability for
   third parties to analyze human behaviour.  It should be noted that
   any data that could identify an individual is personally identifiable
   information (PII).  This means that information which can be used to
   distinguish an indivual from other individuals can be considered as
   personally identiable information.  The access and control of
   personally identifiable information by a third party is a (potential)
   liability for both the third party and the individual.  This
   liability could for example translate into a physical risk for the
   individual or into a legal risk for the third party under information
   security and privacy laws.

   Some network operators argue that without the opportunity to
   persistently identify individual users it becomes harder to thwart
   attacks and troubleshoot network issues.  Whereas identification
   might be helpful to address issues in some cases, it poses an
   inherent threat to the anonymity of users.  Not protecting the
   anonymity of users leads to a deterioration of the right to privacy,
   and the right to freedom of opinion and expression.  There can be
   limitations the right to privacy and freedom of expression, but these

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   should always be provided by law and necessary and proportionate to
   achieve one of a handful of legitimate objectives.  It is clear that
   anonymity may make system and network administration different.  To
   quote [RFC7824], "Those properties (stable and trackable IP
   addresses, derived from static identifiers) are convenient for system
   administrators".  Here, there is a clear and fundamental tussle
   between the protection of the users and the ability of the system and
   network administrator to continue their work in the same way.

   Anonymity will always be a balancing act between user protection
   (which requires a high level of anonymity) and other requirments for
   operations and research, such as routing information.  Anonymity is
   by no means achieved by default in an online environment, nor has it
   been a strong consideration in protocol development in the
   development of the Internet.  Increasing anonymity in the digital
   environment is not an easy task, exactly because the ubiquity of data
   that is generated and stored.  But exactly the fact that we generate
   so much data urges us to address this issue.

4.  Example of use cases

4.1.  Simultaneous use

   One user may use concurrently several identities, mixing them in
   operations, while wanting to keep them distinct.  The protocol and
   its implementations should not preclude this use.

4.2.  Successive use

   One user may switch from one identity to another.  In that case, it
   must be doable without a "bleedover" from the old identity to the new

4.3.  TODO

   TODO more use cases

5.  Practical advices

5.1.  Protocol developers

   First, the protocol should avoid to have mandatory persistent

   Even without persistent identifiers, anonymity could be broken by
   examining the patterns of access.  If an user visits each morning the
   three same Web sites, always in the same order, it will be easy to
   identify them even without persistent identifier.  Protocol designers

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   should therefore ask themselves if patterns are easily visible, or
   obfuscated in some way.

   If the protocol collects data and distributes it (see [RFC6235]),
   "anonymizing" the data is often suggested but it is notoriously hard.
   Do not think that just dropping the last byte of an IP address
   "anonymizes" data.

   Pay attention to the fact that Internet actors do not all see the
   same thing.  Consider the anonymity of the user with respect to:

   -  local network operator

   -  other networks you connect to

   -  your communications peer on the other end of the pipe

   -  intermediaries ([RFC6973])

   -  enablers ([RFC6973])

   -  someone who is in several roles, for instance a big state
      surveillance agency

5.2.  Protocol implementors

   Avoid adding options or configurations that create or might lead to
   patterns or regularities that are not explicitely required by the

   An example is DHCP where sending a persistent identifier as the
   client name was not mandatory but, in practice, done by many
   implementations, before [RFC7844].

   If an implementation allows for identity management, there should be
   a clear barrier between the identities to ensure that they cannot
   (easily) be associated with each other.

   If there are anonymization option for the protocol, these should be
   enabled by default.

6.  Open Questions

   While analyzing protocols for their impact on users anonymity, would
   it make sense to ask the following questions:

   1.  How does the protocol impact pseudonymity?  If the protocol
       limits the creation of new pseudonyms, it can limit their

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       usefulness to "hide" an user's identity.  For instance, IP
       addresses are pseudonyms but, since they are not under end
       users's control, they have strong linkability.  That's why they
       are rightly regarded as personal identifiers [EUcourt].  On the
       other hand, Bitcoin addresses are pseudonyms with limited
       linkability, since the user can always create a lot of them.

   2.  Could there be more advice for protocol developers and
       implementers to improve anonymity?  (Besides the ones in
       Section 5.)

7.  Security Considerations

   As this draft concerns a research document, there are no security

8.  IANA Considerations

   This document has no actions for IANA.

9.  Research Group Information

   The discussion list for the IRTF Human Rights Protocol Considerations
   proposed working group is located at the e-mail address hrpc@ietf.org
   [1].  Information on the group and information on how to subscribe to
   the list is at https://www.irtf.org/mailman/listinfo/hrpc [2]

   Archives of the list can be found at: https://www.irtf.org/mail-
   archive/web/hrpc/current/index.html [3]

10.  Objections against anonymity

   TODO: should be turned into an appendix.  This draft is about how to
   allow anonymity, not about how to fight it.

   For a long time, there have been objections against anonymity.  This
   document won't attempt to rebuke them all, since it is concerned
   about how to ensure that protocols allow anonymity.  But it is
   interesting to keep in mind that protocols never forbid anonymity.
   If smeones want his or her actions to be trackable, and under her or
   his official name, they can do so, by adding this information to
   their messages.  In the same way, people are free not to engage with
   anonymous entities, in the same way that a SIP use, for instance, is
   free not to pick up a call if it comes from
   sip:anonymous@anonymous.invalid.  This document is concerned about
   enabling anonymity, not about mandating it.

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11.  References

11.1.  Informative References

              Pfitzmann, A. and M. Hansen, "A terminology for talking
              about privacy by data minimization: Anonymity,
              Unlinkability, Undetectability, Unobservability,
              Pseudonymity, and Identity Management", 2010,

              Article29, ., "Opinion 05/2014 on Anonymisation
              Techniques", 2014, <http://ec.europa.eu/justice/data-

   [EUcourt]  "EUCJ Case C-70/10: Scarlet Extended SA vs. Societe belge
              des auteurs, compositeurs et editeurs SCRL (SABAM)", 2011,

   [GDPR]     European Parliament and Council, ., "REGULATION (EU)
              the protection of natural persons with regard to the
              processing of personal data and on the free movement of
              such data, and repealing Directive 95/46/EC (General Data
              Protection Regulation)", 2016, <http://eur-lex.europa.eu/

              de Montjoye, Y., Hidalgo, C., Verleysen, M., and V.
              Blondel, "Unique in the Crowd: The privacy bounds of human
              mobility", 2013,

   [Pew]      Rainie, L., Kiesler, S., Kang, R., and M. Madden,
              "Anonymity, Privacy, and Security Online", 2013,

   [Pew2]     Duggan, M., "Online Harassment", 2014,

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   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC
              Text on Security Considerations", BCP 72, RFC 3552,
              DOI 10.17487/RFC3552, July 2003,

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,

   [RFC6235]  Boschi, E. and B. Trammell, "IP Flow Anonymization
              Support", RFC 6235, DOI 10.17487/RFC6235, May 2011,

   [RFC6973]  Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
              Morris, J., Hansen, M., and R. Smith, "Privacy
              Considerations for Internet Protocols", RFC 6973,
              DOI 10.17487/RFC6973, July 2013,

   [RFC7258]  Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
              Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
              2014, <https://www.rfc-editor.org/info/rfc7258>.

   [RFC7626]  Bortzmeyer, S., "DNS Privacy Considerations", RFC 7626,
              DOI 10.17487/RFC7626, August 2015,

   [RFC7824]  Krishnan, S., Mrugalski, T., and S. Jiang, "Privacy
              Considerations for DHCPv6", RFC 7824,
              DOI 10.17487/RFC7824, May 2016,

   [RFC7844]  Huitema, C., Mrugalski, T., and S. Krishnan, "Anonymity
              Profiles for DHCP Clients", RFC 7844,
              DOI 10.17487/RFC7844, May 2016,

   [RFC7858]  Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
              and P. Hoffman, "Specification for DNS over Transport
              Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
              2016, <https://www.rfc-editor.org/info/rfc7858>.

              The Tor Project, ., "Tor Project - Anonymity Online",
              2007, <https://www.torproject.org/>.

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              Kaye, D., "Anonymity, Privacy, and Security Online (A/
              HRC/29/32)", 2015, <http://www.ohchr.org/EN/HRBodies/HRC/R

   [Utexas]   Narayanan, A. and V. Shmatikov, "Robust De-anonymization
              of Large Sparse Datasets", 2008,

11.2.  URIs

   [1] mailto:hrpc@ietf.org

   [2] https://www.irtf.org/mailman/listinfo/hrpc

   [3] https://www.irtf.org/mail-archive/web/hrpc/current/index.html

Authors' Addresses

   Stephane Bortzmeyer

   EMail: bortzmeyer+ietf@nic.fr

   Niels ten Oever

   EMail: niels@article19.org

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