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Network Working Group                                      H. Tschofenig
Internet-Draft                                    Nokia Siemens Networks
Intended status: Informational                                 S. Turner
Expires: April 26, 2013                                       IECA, Inc.
                                                               M. Hanson
                                                                 Mozilla
                                                        October 23, 2012


      An Inquiry into the Nature and the Causes of Web Insecurity
                 draft-tschofenig-secure-the-web-04.txt

Abstract

   The year 2011 has been quite exciting from a Web security point of
   view: a number of high-profile security incidents have gotten a lot
   of press attention but also new initiatives, such as the National
   Strategy for Trusted Identities in Cyberspace (NSTIC), had been
   launched to improve the Web identity eco-system.  The NSTIC strategy
   paper, for example, observes problems with Internet security due to
   the widespread usage of low-entropy passwords and the lack of widely
   deployed authentication and attribute assurance services.

   With this memorandum we try to develop a shared vision for how to
   deal with the most pressing Web security problems.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 26, 2013.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Passwords  . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   4.  Roadmap  . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   5.  From Two-Party to N-Party  . . . . . . . . . . . . . . . . . . 12
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 15
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 16
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19



























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1.  Introduction

   HTTP is an IETF standard and documented in RFC 2616 [RFC2616] and
   provides the core foundation of the browser-based platform but is
   also widely used for non-browser-based applications in smart phones
   and Internet tablets.  Like any other specification in the IETF HTTP
   also comes with various security mechanims.  Digest authentication
   support in HTTP was published in 1997 with RFC 2069 [RFC2069] and
   later updated in 1999 by RFC 2617 [RFC2617].  The HTTP state
   management mechanism, namely cookies, was initially published in 1997
   with RFC 2109 [RFC2109], revised in 2000 by RFC 2965 [RFC2965], and
   obsoleted by RFC 6265 [RFC6265].

   For client side authentication for HTTP-based protocols two different
   solution tracks have been offered from the IETF, namely TLS client
   side authenication and also application level authentication via HTTP
   basic and digest.  TLS-based client authentication using certificates
   was quite complex for end users to configure (and still is today).
   HTTP based authentication on the other hand did not found widespread
   usage either for a number of reasons.  First, the user interface was
   rendered differently than regular Web application forms making it
   less attractive for Web developers and users.  At that time HTTP had
   a semantic that was closer to file system access control and
   therefore the decision making process was binary, either the user was
   granted access to the resource or it wasn't.  With the HTTP 401 there
   was no way for a user to, for example, recover from a lost password
   or other forms of failure cases.  The authentication and
   authorization process was not seen as continuium but rather as a
   binary decision.  For these reasons form-based authentication
   mechanisms had found widespread acceptance by the Web application
   developer community.

   Many Web sites decided to deploy their own authentication
   infrastructure and to store cleartext credentials, since most of them
   use password-based authentication.  As reported in a New York Times
   article from October 2012 [NYT-2Factor] a recent analysis of a leaked
   large password database revealed that among 3.4 million passwords
   (among the 30.3 million passwords) consisting of nothing but four
   digits.  The top 20 passwords account for nearly 27% of the total.
   This even makes online guessing attacks feasible.  Users also share
   the same password across multiple sites making it easy for an
   adversary to utilize credentials obtained from one site to also gain
   access on other Web sites.

   Breach notification laws forced companies to inform their customers
   about incidents.  Consequently, the community became aware of the
   degree of password leakage due to unauthorized access to these
   credential databases.  For example, in April 2011 Sony experienced a



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   data breach within their PlayStation Network and 100 million users
   accounts were compromised.  This is only one out of thousands of data
   breaches collected by the Privacy Rights Clearing House [DataBreach].
   In most cases these security vulnerabilities are due to
   misconfiguration, security vulnerabilities in software which can be
   exploited via buffer overflow attacks, and SQL injection due to
   insufficient input parameter verification.

   In addition, cookies are still the most common mechanism for session
   management, i.e., a non-cryptographic way to bind the initial, often
   better protected, authentication procedure to the subsequent protocol
   exchanges.  The non-cryptographic session management gives attackers
   the ability to perform session hijacking.  This is of particular
   concern when users access Internet services using insecure WLAN
   hotspots.  Firesheep [FireSheep], a Firefox plugin that worked as a
   packetsniffer demonstrated this vulnerability to the non-expert
   community and made session hijacking 'friendly to use' for a broader
   community.

   A number of trends had been observed during the last couple of years,
   as briefly summarized below.

   From Documents to Mobile Code:  During the last 10 years the Web has
      changed quite fundamentally with the widespread usage of
      JavaScript.  While Web pages have for a long time been dynamically
      generated the ever increasing capabilities of JavaScript, with
      respect to functionality and performance, have changed the
      security model.  A typical Website collects content from multiple
      other Web sites and delivers it to the user's browser and by
      delivering code inside HTML new security challenges have emerged.
      Also the standardization landscape had been challenged by this new
      development and [I-D.tschofenig-post-standardization] documents
      architectural implications.

   Mashups and Data Sharing:  With the increasing specialization of Web
      sites developers started to outsource functionality to other
      sites.  Partially this is a user-convenience aspect (e.g., users
      do not want to create a new address book with every site, publish
      their latest status on each and every site again and again) but
      often also driven by business interestes.  In any case, the need
      to access resources hosted on other sites emerged and often these
      resources were not visible to everyone.  Sharing long-term
      passwords is considered a bad habit and consequently the Web
      Authorization (OAuth) protocol [RFC6749] started to become used
      widely.  OAuth avoids the need to share long-term credentials with
      random Web sites.





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   The Real-Time Web:  As HTTP became the protocol of choice for many
      application developers, also because of it's ability to go through
      firewalls and NATs, requirements for asynchronous protocol
      communication had to be addressed as well.  HTTP, as a request/
      response protocol, was initially not designed for pushing data
      from the server-side to the client as soon as it is available.
      Long polling requests and other tricks had been used to allow bi-
      directional communication between the HTTP client and the HTTP
      server.  The efforts in the BiDirectional or Server-Initiated HTTP
      (hybi) working group improves the communication capabilities of
      HTTP.  To allow one Web browser to communicate directly with
      another Web browser the same-origin security framework utilized by
      the browser has to be bypassed and the work on Real-Time
      Communication in WEB-browsers (rtcweb) was created to develop a
      architecture [I-D.ietf-rtcweb-security] and in
      [I-D.ietf-rtcweb-overview].  Extending Web clients with real-time
      communication capabilities opens the doors for a large number of
      applications that had previously only been available for
      downloadable applications.

   With the increasing number of security challenges and developments in
   the Web application environment the standards community was
   challenged to initiate activities.  Examples include the development
   of HTTP Strict Transport Layer Security (HSTS)
   [I-D.ietf-websec-strict-transport-sec] that allows Web sites to
   declare themselves accessible only via secure connections.  The
   attempt to clarify the Web Origin Concept [I-D.ietf-websec-origin],
   which covers the principles that underlies the concept of origin as
   used to scope of authority or privilege by user agents.  The work
   around Content Security Policy (CSP) [CSP] that allows Web
   application developers to declare a set of content restrictions for a
   web resources.  The OAuth protocol that allows secure and privacy-
   friendly sharing of resources.  The work on Javascript Object Signing
   and Encryption to give Web developers better ways to protect the
   exchange of JSON data structures.  The W3C Web Cryptography API that
   defines JavaScript extensions that enables developers to implement
   secure application protocols within Web applications.

   A lot has changed over the last 10 years in the Web eco-system.
   While astonishing progress has been made in getting the Web
   application eco-system on a par with native applications the
   foundation of the Web platform is still unable to address many of the
   most common security vulnerabilities; problems the Internet community
   had been fighting against for over a decade and had solved for other
   application protocol frameworks and Internet deployment environments.

   It is time to tackle this problem and to develop a common
   understanding of the problem and the desired design goals.



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2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].














































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3.  Passwords

   Passwords have a long history in authentication protocols on the
   Internet.  They appear to be convient for users and are easy to
   provision to users by many Web site.  Still, passwords present a
   number of challenges, including:

   o  Users re-use the same password at multiple sites.  This allows a
      rouge Website provider to attempt to impersonate users on other
      sites.  It also allows a hacker to use stolen passwords obtained
      from one site to be used at a non-compromised site.

   o  Password are stored in cleartext in most cases.  In case of a data
      breach account information, including the password, becomes
      accessible to an attacker.

   o  Users are tricked in typing their password into a Website
      maintained by phishing attempts.  Furthermore, some Websites
      request username and password for access to protected resources
      maintained by other Websites.  While there are technical ways to
      avoid the need for such long-term password sharing practice using
      OAuth some Websites still ask users.

   o  Many password based authenication protocols are not secure against
      eavesdropping, or allow easy ways for offline dictionary attacks.

   o  When end systems are compromised as well then a keyboard logger
      can capture any password sequence a user enters.

   So, why do we need passwords at all?  It is easy to come up with
   solutions that use hardware-based mechanisms (e.g., such as OTP
   tokens), mobile phones, etc.  [Quest] lists some of these mechanisms
   and makes an attempt to classify them.  Many of the analysed
   authentication mechanisms provide additional security but have design
   limitations regarding usability and incremental deployment.  There
   are, however, reasons why alternatives have not found widespread
   deployment on the Internet, such as

   o  Passwords are cheap (at least the primary costs) for user's and
      service providers.  Hardware tokens on the other hand have a
      certain amount of cost associated with them.

   o  Provisioning new users with passwords is easy.  Tools and
      processes exist and are widely accepted.

   o  Service providers have no external dependency when they manage
      user accounts themselves (unlike with many third party identity
      management solutions).



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   o  Users are familiar with password-based systems and the acceptance
      is good.

   o  Passwords can easily be delegated to others.

   o  Users typically feel quite secure when they are using shared
      secrets and it fits into their mental model of self-securing.

   o  Passwords can easily be transferred to multiple devices used by a
      single user.

   Note that the credential type and the actual form of where these
   credentials are stored (e.g., software, hardware) is orthogonal to
   the actual identity proofing process.  Stronger forms of identity
   proofing (e.g., requiring in-person passport verification) can be
   quite expensive.  There are also secondary costs in the form of
   support calls and education if credential provisioning is more
   complicated, as it is often the case with client certificates.

   Regardless how many disadvantages passwords have they will be with us
   for a long time.  As such, out attempt is therefore to start from the
   currently deployment and to look towards a future where fewer of them
   are used, and if they are used then in a more secure fashion.




























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4.  Roadmap

   It is our aim to accomplish three types of goals:

   1.  Reduce the number of passwords used on the Web

   2.  Increase security of how passwords are used (for example using
       two-factor authentication).  With the RSA patents for one-time
       password based authentication expiring the usage of the work by
       the Initiative for Open Authentication (OATH) with their HMAC-
       Based One-time Password (HOTP) algorithm (RFC 4226 [RFC4226]) and
       the Time-based One-time Password (TOTP) algorithm (RFC 6238
       [RFC6238]) has increased.

   3.  Broaden the use of other, non-password-based credentials.  The
       weaknesses related to compromised password databases and the
       unauthorized access to these stored credentials is difficult to
       avoid entirely without switching to stronger credentials or
       without outsourcing those functions to specifialized third party
       identity providers.

   A non-goal of this document is to evaluate ways for improving
   identity proofing, which is a requirement for accomplishing higher
   levels of assurance.

   We do not believe that the technical community should be attempting
   to come up with the single and best solution to satisfy these three
   goals.  We would like to leave room for innovation and allow many
   different solutions to co-exist to best suite their deployment.

   Subsequently, we try to highlight a few guiding principles in an
   attempt to come with a way forward.

   Move Authentication down into the Platform:

      Exposing authentication protocol functionality to the user and
      requiring Web application developers to write security related
      code has proven to lead to problems.  Avoid user interaction
      related to security whenever possible but keep in mind that
      authorization decisions, particularly with regard to data sharing,
      require a consent.  Ensure that library support is available for
      Web developers to allow them easy integration of security
      functionality into their applications.  Unfortunately, a protocol
      design also needs to consider the transition scenario where the
      Web endpoints are not yet upgraded to support the new
      functionality and that the authentication functionality is not yet
      available.




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   Design for Growth:

      No single authentication mechanism nor credential type is able to
      fulfill all use cases.  Design for later extensions and develop
      the protocol architecture in such a way that components are
      interchangable.  In particular, there are a number of
      authentication mechanisms already in use in other deployment
      environments.


   Context Matters:

      Users require context for all disclosures and the sequence of
      interactions matters.  A monolitic authentication protocol that
      provides mutual authentication is less likely going to capture the
      context related disclosures.  Server-side authentication is the
      first interaction that will have to be provided to guarantee
      genuine content as well as the prerequisity of an early setup for
      a confidentiality protected channel.  Client side authentication
      may, however, come at a much later stage of the application
      interaction.  It is often bundled with an authorization decision
      where different application execution paths depend on the level of
      authorization.


         Discussion: Is it indeed given that client authentication will
         have to happen at a later stage given that platform-level
         authentication proliferates (particularly or mobile phone
         applications) and "authenticated by default" becomes the norm?
         If so, then strong signals in UIs of authenticated status,
         identity selection, and anonymous/pseudonymous modes become
         more important.  One could compare this to the evolution in the
         telephony communication where caller ID information was
         initially not provided but became the norm later and blocking
         the caller ID instead became the expection.


   Transform Long-Term Passwords to Short-Term Credentials:

      One of the function of authentication protocols is to transform
      long-term credentials into short term secrets.  Long-term
      credentials, such as passwords, require substantial protection in
      a protocol exchange and therefore this interaction often leads to
      a computationally expensive, multi-roundtrip protocol exchange.
      We do, however, encourage protocol designers to make heavier use
      of this transformation step into short term credentials.





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   Keep the User Experience in Mind:

      Design your protocol stack in such a way that developers up the
      stack can give good advice to users.  The use case analysis should
      include common failure scenarios since error paths need as much
      expressiveness as success paths, whereby expressiveness refers to
      the ability to communicate with the user about failure cases.

   TLS Always:

      The initial step of entity authentication cannot be seen in
      isolution of the ultimate purpose of securing an entire applicatio
      interaction that requires session management to take place.  While
      this session management today happens in most cases in a non-
      cryptographic way (i.e., without data origin authentication) we
      believe it is time revisit this practice.  Designing a new
      cryptographic session management concept is questionable given the
      already available tools, such as TLS that provides a secure
      session management using the TLS Record Layer.  The usage of the
      Record Layer is, compared to the TLS Handshake protocol, fairly
      computationally less time-consuming






























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5.  From Two-Party to N-Party

   It would be short sighted to write about a topic like this without
   touching a commonly desired way to reduce the number of long term
   credentials: federated logins

   Federated login allows a user to utilize his credential obtained from
   one organization, acting as the Identity Provider, for accessing a
   resource at another entity, who acts as a Relying Party.  While this
   approach addresses some of our design goals it causes secondary
   problems to appear - particularly related to privacy.

   The following issues in this transition from a two-party to a three-
   party model are to observe:

   Discovery:

      How do the three parties find each other?  In particular, how does
      the user (via his or her user agent) inform the relying party
      about the identity provider it wants to use?  How does the relying
      party inform the user agent (and user) about the identity
      providers it is able and willing to interact with?  Without any
      changes to the end device relying parties often display icons of
      identity providers: the more identity providers they support the
      more icons are displayed to the user.  This is also known as the
      NASCAR problem.


   Mutual Authentication:

      How do we ensure that each party is authenticated to each other?


   Trust and Permissions:

      What information should the user share with the relying party and
      how can he be reassured that the information is used in the way he
      permitted?  What information is needed by the Relying Party for
      the application specific functionality?  How is the identity
      provider able to protect its users against misbehaving relying
      parties?


   Collusion:

      There are three related properties systems should be tying to
      provide:




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      Relying parties can be prevented from knowing the real or
      pseudonymous identity of an individual, since the identity
      provider is the only entity involved in verifying identity.

      Relying parties that collude can be prevented from using an
      individual's credentials to track the individual.  That is, two
      different relying parties can be prevented from determining that
      the same individual has authenticated to both of them.  This
      requires that each relying party use a different means of
      identifying individuals.

      The identity provider can be prevented from knowing which relying
      parties an individual interacted with.  This requires avoiding
      direct communication between the identity provider and the relying
      party at the time when access to a resource by the initiator is
      made.


   Security:

      Keeping data secure at rest and in transit is another important
      component of security and privacy protection.  How can it be
      ensured that the interactions between the three parties are not
      manipulated?  An identity provider providing services to many
      relying parties is exposed to increased risk of a at breach via an
      nauthorized access to the credential database.  How can this
      increased security protection be provided?


   Note: While this text talks about three parties there may well be
   more parties involved in the exchange.  The role of the identity
   consists of a credential provider and an attribute provider that may
   be provided by different parties.  Furthermore, attributes associated
   with personal data may be contributed by multiple attribute
   providers, not just by a single entity.  There may also be additional
   parties involved in the communication between the identity provider
   and the relying party the trust path from the identity provider to
   the relying party.













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6.  IANA Considerations

   This document does not require actions by IANA.
















































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7.  Acknowledgments

   The content of this document has been created based on discussions
   with a number of persons, including

   o  Jeff Hodges

   o  Michael Garcia

   o  Adam Barth

   o  Brad Hill

   o  Dan Mills

   o  Ed Felton

   o  Tara Whalen

   o  Andy Steingruebl

   o  Tim Polk

   o  Dirk Balfanz

   o  Nico Williams

   o  Tobias Gondrom

   o  Julian Reschke

   We would like to thank them for their input.  We would also like to
   thank the participants of the May 2011 W3C Identity in the Browser
   workshop for their discussion feedback.

















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8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A., and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

   [RFC2109]  Kristol, D. and L. Montulli, "HTTP State Management
              Mechanism", RFC 2109, February 1997.

   [RFC6265]  Barth, A., "HTTP State Management Mechanism", RFC 6265,
              April 2011.

   [RFC2965]  Kristol, D. and L. Montulli, "HTTP State Management
              Mechanism", RFC 2965, October 2000.

8.2.  Informative References

   [RFC6749]  Hardt, D., "The OAuth 2.0 Authorization Framework",
              RFC 6749, October 2012.

   [RFC5849]  Hammer-Lahav, E., "The OAuth 1.0 Protocol", RFC 5849,
              April 2010.

   [I-D.ietf-websec-origin]
              Barth, A., "The Web Origin Concept",
              draft-ietf-websec-origin-06 (work in progress),
              October 2011.

   [I-D.ietf-websec-strict-transport-sec]
              Hodges, J., Jackson, C., and A. Barth, "HTTP Strict
              Transport Security (HSTS)",
              draft-ietf-websec-strict-transport-sec-14 (work in
              progress), September 2012.

   [RFC2069]  Franks, J., Hallam-Baker, P., Hostetler, J., Leach, P.,
              Luotonen, A., Sink, E., and L. Stewart, "An Extension to
              HTTP : Digest Access Authentication", RFC 2069,
              January 1997.



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   [I-D.ietf-httpbis-p7-auth]
              Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
              (HTTP/1.1): Authentication", draft-ietf-httpbis-p7-auth-21
              (work in progress), October 2012.

   [I-D.tschofenig-post-standardization]
              Tschofenig, H., Aboba, B., Peterson, J., and D. McPherson,
              "Trends in Web Applications and the Implications on
              Standardization", draft-tschofenig-post-standardization-02
              (work in progress), May 2012.

   [I-D.ietf-rtcweb-overview]
              Alvestrand, H., "Overview: Real Time Protocols for Brower-
              based Applications", draft-ietf-rtcweb-overview-04 (work
              in progress), June 2012.

   [I-D.ietf-rtcweb-security]
              Rescorla, E., "Security Considerations for RTC-Web",
              draft-ietf-rtcweb-security-03 (work in progress),
              June 2012.

   [RFC4226]  M'Raihi, D., Bellare, M., Hoornaert, F., Naccache, D., and
              O. Ranen, "HOTP: An HMAC-Based One-Time Password
              Algorithm", RFC 4226, December 2005.

   [RFC6238]  M'Raihi, D., Machani, S., Pei, M., and J. Rydell, "TOTP:
              Time-Based One-Time Password Algorithm", RFC 6238,
              May 2011.

   [CSP]      "Content Security Policy 1.0", July 2012.

   [FireSheep]
              "FireSheep, available at
              http://en.wikipedia.org/wiki/Firesheep", October 2012.

   [NYT-2Factor]
              "Doing the Two-Step, Beyond the A.T.M., New York Times,
              available at http://www.nytimes.com/2012/10/14/technology/
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   [DataBreach]
              "Privacy Rights Clearinghouse - Data Breaches, available
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   [Quest]    "The Quest to Replace Passwords: A Framework for
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              Proc. IEEE Symp. on Security and Privacy 2012 (Oakland
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Authors' Addresses

   Hannes Tschofenig
   Nokia Siemens Networks
   Linnoitustie 6
   Espoo  02600
   Finland

   Phone: +358 (50) 4871445
   Email: Hannes.Tschofenig@gmx.net
   URI:   http://www.tschofenig.priv.at


   Sean Turner
   IECA, Inc.
   3057 Nutley Street, Suite 106
   Fairfax, VA  22031
   USA

   Phone:
   Email: turners@ieca.com


   Mike Hanson
   Mozilla


   Phone:
   Email: mhanson@mozilla.com






















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