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</style><link href="http://www.w3.org/StyleSheets/TR/W3C-WD" rel="stylesheet" type="text/css" charset="utf-8"></head><body style="display: inherit; "><div class="head"><p><a href="http://www.w3.org/"><img width="72" height="48" src="http://www.w3.org/Icons/w3c_home" alt="W3C"></a></p><h1 class="title" id="title">Web Application Privacy Best Practices</h1><h2 id="w3c-working-draft-04-august-2011">W3C Working Draft 04 August 2011</h2><dl><dt>This version:</dt><dd><a href="http://www.w3.org/TR/2011/WD-app-privacy-bp-20110804/">http://www.w3.org/TR/2011/WD-app-privacy-bp-20110804/</a></dd><dt>Latest published version:</dt><dd><a href="http://www.w3.org/TR/app-privacy-bp/">http://www.w3.org/TR/app-privacy-bp/</a></dd><dt>Latest editor's draft:</dt><dd><a href="http://dev.w3.org/2009/dap/privacy-practices/">http://dev.w3.org/2009/dap/privacy-practices/</a></dd><dt>Previous version:</dt><dd>none</dd><dt>Editor:</dt><dd><span>Frederick Hirsch</span>, <a href="http://www.nokia.com/">Nokia</a></dd>
</dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2011 <a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p><hr></div>
    <div id="abstract" class="introductory section"><h2>Abstract</h2>
      This document describes privacy best practices for web
      applications, including those that might use device
      APIs.
    </div><div id="sotd" class="introductory section"><h2>Status of This Document</h2><p><em>This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at http://www.w3.org/TR/.</em></p>
      <p>
        This is a First Public Working Draft of a document that is expected to
      be further updated based on both Working
      Group input and public comments. The Working Group anticipates to
      eventually publish a stabilized version of this document as a W3C
      Working Group Note.
      </p>
    <p>This document was published by the <a href="http://www.w3.org/2009/dap/">Device APIs and Policy Working Group</a> as a Working Draft. If you wish to make comments regarding this document, please send them to <a href="mailto:public-device-apis@w3.org">public-device-apis@w3.org</a> (<a href="mailto:public-device-apis-request@w3.org?subject=subscribe">subscribe</a>, <a href="http://lists.w3.org/Archives/Public/public-device-apis/">archives</a>). All feedback is welcome.</p><p>Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.</p><p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent Policy</a>. The group does not expect this document to become a W3C Recommendation. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/43696/status" rel="disclosure">public list of any patent disclosures</a> made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of the W3C Patent Policy</a>.</p></div><div id="toc" class="section"><h2 class="introductory">Table of Contents</h2><ul class="toc"><li class="tocline"><a href="#introduction" class="tocxref"><span class="secno">1. </span>Introduction</a></li><li class="tocline"><a href="#privacybydesign" class="tocxref"><span class="secno">2. </span>Privacy By Design</a></li><li class="tocline"><a href="#usercentric" class="tocxref"><span class="secno">3. </span>User Centric Design</a></li><li class="tocline"><a href="#data-minimization" class="tocxref"><span class="secno">4. </span>Minimize collection and
      transmission of personal data</a></li><li class="tocline"><a href="#data-confidentiality" class="tocxref"><span class="secno">5. </span>Maintain the confidentiality of personal data</a></li><li class="tocline"><a href="#access-log" class="tocxref"><span class="secno">6. </span>Control and log access</a></li><li class="tocline"><a href="#bp-summary" class="tocxref"><span class="secno">7. </span>Best Practices Summary</a></li><li class="tocline"><a href="#references" class="tocxref"><span class="secno">A. </span>References</a><ul class="toc"><li class="tocline"><a href="#normative-references" class="tocxref"><span class="secno">A.1 </span>Normative references</a></li><li class="tocline"><a href="#informative-references" class="tocxref"><span class="secno">A.2 </span>Informative references</a></li></ul></li></ul></div> <!-- abstract -->


    <div id="introduction" class="section">
      <!--OddPage--><h2><span class="secno">1. </span>Introduction</h2>
      <p>
        This document outlines good privacy practices for web
        applications, including those that might use
        device APIs. This continues the work on privacy best practices
        in section 3.3.1 on "User Awareness and Control"  Mobile Web Application Best Practices [<cite><a class="bibref" rel="biblioentry" href="#bib-MWABP">MWABP</a></cite>]. It does not repeat the privacy principles and
        requirements documented in the Device API Privacy Requirements Note
        [<cite><a class="bibref" rel="biblioentry" href="#bib-DAP-PRIVACY-REQS">DAP-PRIVACY-REQS</a></cite>] which should also be consulted.
      </p>
    </div>
    <div id="privacybydesign" class="section">
      <!--OddPage--><h2><span class="secno">2. </span>Privacy By Design</h2>
      <p>
        The principles of "Privacy by Design" should be reflected in the
        web application design and implementation, including the use
        of device APIs.
        These are enumerated below and in more detail in the reference
      [<cite><a class="bibref" rel="biblioentry" href="#bib-PRIVACY-BY-DESIGN">PRIVACY-BY-DESIGN</a></cite>].</p>
      <div class="practice">
        <p>
        <span id="bp-privacy-by-design" class="practicelab">Best Practice 1: Follow "Privacy By Design" principles</span>.</p>
        <p class="practicedesc">
          Proactively consider privacy, make preservation of
          privacy the default, including privacy in a
          user-centric and transparent design without making
          tradeoffs against privacy for other features as
          privacy is possible along with other functionality.
        </p>
        <p>These principles include the following:</p>
        <ol>
          <li>Proactive not Reactive; Preventative not Remedial</li>
          <li>Privacy as the Default Setting</li>
          <li>Privacy Embedded into Design</li>
          <li> Full Functionality — Positive-Sum, not Zero-Sum</li>
          <li>End-to-End Security — Full Lifecycle Protection</li>
          <li>Visibility and Transparency — Keep it Open</li>
          <li>Respect for User Privacy — Keep it User-Centric</li>
        </ol>
      </div>
      </div>
    <div id="usercentric" class="section">
      <!--OddPage--><h2><span class="secno">3. </span>User Centric Design</h2>
      <p>Privacy should be user centric, giving the user understanding
      and control over use of their personal data.</p>
      <div class="practice">
        <p><span id="bp-user-driven" class="practicelab">Best Practice 2: Enable the user to make informed decisions about
            sharing their personal information with a service.
        </span></p>
        <p class="practicedesc">
          The end user should have enough information about a service
          and how it will user their personal information to make an
          informed decision on whether to share information with that service.
          This should include understanding of the data to be shared,
          clarity about how long data will be kept
          and information with whom it will be shared (and for what purpose).
        </p>
      </div>
      <div class="practice">
        <p><span id="bp-choices-in-context" class="practicelab">Best Practice 3: Enable the user to make decisions at the
        appropriate time with the correct contextual information.
        </span></p>
        <p class="practicedesc">
          The user should have the opportunity to decide whether to
          share information (and what to share) at the time it is
          needed. This is necessary as the decision can depend on the
          context, including the details of what the user is trying to
          accomplish, the details of that task, and differences in how
          the service will operate, use and share data.
        </p>
<!--         <p class="practicedesc"> -->
<!--           Examples are the presentation of a "picker" -->
<!--           interface to a user for selecting contacts fields of -->
<!--           potential contacts returned from a find operation in -->
<!--           the contacts  API [[CONTACTS-API]], or the selection -->
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<!--         </p> -->
<!--         <p class="practicedesc"> -->
<!--           Another similar example is -->
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<!--         </p> -->
<!--         <p class="practicedesc"> -->
<!--           These are examples of granting permission implicitly -->
<!--         through action.</p> -->
      </div>
      <div class="practice">
        <p><span id="bp-sp-choices" class="practicelab">Best Practice 4: When learning user privacy
        decisions and providing defaults, allow the user to easily view and
        change these previous decisions.
        </span></p>
        <p class="practicedesc">
          A service may learn and remember personal information of a
         user in order to improve a service. One example is
         remembering a billing address, another might be remembering
         payment information. When doing so the service should make it
         clear to a user which information is retained, how it is
         used, and give the user an opportunity to correct or remove
         the information.
        </p>
      </div>
      <div class="practice">
        <p><span id="bp-usability" class="practicelab">Best Practice 5: Focus on usability and avoid needless prompting.
        </span></p>
        <p class="practicedesc">
          Focus on usability should improve a service as well as
          making it easier for a user to understand and control use of their
          personal information. Minimize use of modal dialogs as they
          harm the user experience and many users will not understand how to
          respond to prompts, choosing a choice that enables them to
          continue their work
          [<cite><a class="bibref" rel="biblioentry" href="#bib-GEOLOCATION-PRIVACY">GEOLOCATION-PRIVACY</a></cite>].
        </p>
      </div>
      <div class="practice">
        <p><span id="bp-clarity" class="practicelab">Best Practice 6: Be clear and
        transparent to users regarding
        potential privacy concerns.
        </span></p>
        <p class="practicedesc">
          The end user should understand if information is being used
          by the service itself or being shared with a third
          party, especially when third party services are
          involved in a "mashup".
        </p>
      </div>
      <div class="practice">
        <p><span id="bp-clarify-one-shot-or-repeated" class="practicelab">Best Practice 7: Be clear as to whether information is
        needed on a one-time basis or is necessary for a period of
        time and for how long.
        </span></p>
        <p class="practicedesc">
          The end user should understand whether information collected is
          for a single use or will be retained and have an impact over time.
        </p>
      </div>
    </div>
    <div id="data-minimization" class="section">
      <!--OddPage--><h2><span class="secno">4. </span>Minimize collection and
      transmission of personal data</h2>
        <p>Review the data and how it is structured and used, minimizing
        the amount and detail of data required to provide a service.
        </p>
        <div class="practice">
          <p><span id="bp-data-granularity" class="practicelab">Best Practice 8: Request the minimum number of data
          items at the
          minimum level of detail needed to provide a service.</span></p>
          <p class="practicedesc">
            As an example, an address book entry is not the
            natural level of granularity as a user may wish to
            share various individual address
            book fields independently. Thus the natural level of
            granularity in an address book is a field and no
            more than the necessary fields should be provided in
            response to
            an address book entry request.
          </p>
        </div>
        <div class="practice">
          <p><span id="bp-data-retention" class="practicelab">Best Practice 9:
          Retain the minimum amount of data at the minimum level of detail for
          the minimum amount of time needed.
          Consider potential misuses of retained data and
          possible countermeasures.
          </span></p>
          <p class="practicedesc">
            As an example, retaining user payment information
            entails the risk of this information being stolen and
            misused. Perhaps it does not need to be retained but
            if it is (with user permission) perhaps it should be
            encrypted (to give one possible countermeasure).
          </p>

        </div>
    </div>
    <div id="data-confidentiality" class="section">
      <!--OddPage--><h2><span class="secno">5. </span>Maintain the confidentiality of personal data</h2>
      <div class="practice">
        <p><span id="bp-use-https" class="practicelab">Best Practice 10:
        Maintain the confidentiality of user data in
        transmission, for example using <code>HTTPS</code> for
        transport rather than <code>HTTP</code>.
        </span></p>
        <p class="practicedesc">
          Use of <code>HTTPS</code> can provide confidentiality of
          personal data in
          transport when an appropriate cipher suite is
          required.  This should be done for sensitive personal
          information unless confidentiality can be assured by other means.
        </p>
      </div>
      <div class="practice">
        <p><span id="bp-secure-storage" class="practicelab">Best Practice 11:
        Maintain the confidentiality of user data in
        storage.
        </span></p>
        <p class="practicedesc">
          The confidentiality of personal information should be
          maintained  when in storage, to prevent inadvertent or
          malicious loss (e.g. break in to a server, theft of backups
          or other threats).
        </p>
      </div>
    </div>
    <div id="access-log" class="section">
      <!--OddPage--><h2><span class="secno">6. </span>Control and log access</h2>
        <div class="practice">
          <p><span id="bp-audit-log" class="practicelab">Best Practice 12: Control and log access to data.</span></p>
          <p class="practicedesc">
            Control access to information through access controls and
            log access.
          </p>
        </div>
    </div>
    <div id="bp-summary" class="section"><!--OddPage--><h2><span class="secno">7. </span>Best Practices Summary</h2><ul><li><a href="#bp-privacy-by-design">Best Practice 1</a>: Follow "Privacy By Design" principles</li><li><a href="#bp-user-driven">Best Practice 2</a>: Enable the user to make informed decisions about
            sharing their personal information with a service.
        </li><li><a href="#bp-choices-in-context">Best Practice 3</a>: Enable the user to make decisions at the
        appropriate time with the correct contextual information.
        </li><li><a href="#bp-sp-choices">Best Practice 4</a>: When learning user privacy
        decisions and providing defaults, allow the user to easily view and
        change these previous decisions.
        </li><li><a href="#bp-usability">Best Practice 5</a>: Focus on usability and avoid needless prompting.
        </li><li><a href="#bp-clarity">Best Practice 6</a>: Be clear and
        transparent to users regarding
        potential privacy concerns.
        </li><li><a href="#bp-clarify-one-shot-or-repeated">Best Practice 7</a>: Be clear as to whether information is
        needed on a one-time basis or is necessary for a period of
        time and for how long.
        </li><li><a href="#bp-data-granularity">Best Practice 8</a>: Request the minimum number of data
          items at the
          minimum level of detail needed to provide a service.</li><li><a href="#bp-data-retention">Best Practice 9</a>:
          Retain the minimum amount of data at the minimum level of detail for
          the minimum amount of time needed.
          Consider potential misuses of retained data and
          possible countermeasures.
          </li><li><a href="#bp-use-https">Best Practice 10</a>:
        Maintain the confidentiality of user data in
        transmission, for example using <code>HTTPS</code> for
        transport rather than <code>HTTP</code>.
        </li><li><a href="#bp-secure-storage">Best Practice 11</a>:
        Maintain the confidentiality of user data in
        storage.
        </li><li><a href="#bp-audit-log">Best Practice 12</a>: Control and log access to data.</li></ul></div>


<div id="references" class="appendix section"><!--OddPage--><h2><span class="secno">A. </span>References</h2><div id="normative-references" class="section"><h3><span class="secno">A.1 </span>Normative references</h3><p>No normative references.</p></div><div id="informative-references" class="section"><h3><span class="secno">A.2 </span>Informative references</h3><dl class="bibliography"><dt id="bib-DAP-PRIVACY-REQS">[DAP-PRIVACY-REQS]</dt><dd>Alissa Cooper, Frederick Hirsch, John Morris. <a href="http://www.w3.org/TR/2010/NOTE-dap-privacy-reqs-20100629/"><cite>Device API Privacy Requirements</cite></a> 29 June 2010. W3C Note URL: <a href="http://www.w3.org/TR/2010/NOTE-dap-privacy-reqs-20100629/">http://www.w3.org/TR/2010/NOTE-dap-privacy-reqs-20100629/</a>
</dd><dt id="bib-GEOLOCATION-PRIVACY">[GEOLOCATION-PRIVACY]</dt><dd>Marcos Cáceres <a href="http://www.w3.org/2010/api-privacy-ws/papers/privacy-ws-21.pdf"><cite>Privacy of Geolocation Implementations</cite></a>, "W3C Workshop on Privacy for Advanced Web APIs" paper, 12/13 July 2010. URL: <a href="http://www.w3.org/2010/api-privacy-ws/papers/privacy-ws-21.pdf">http://www.w3.org/2010/api-privacy-ws/papers/privacy-ws-21.pdf</a>
</dd><dt id="bib-MWABP">[MWABP]</dt><dd>Adam Connors; Bryan Sullivan. <a href="http://www.w3.org/TR/2010/REC-mwabp-20101214/">Mobile Web Application Best Practices.</a> 14 December 2010. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2010/REC-mwabp-20101214/">http://www.w3.org/TR/2010/REC-mwabp-20101214/</a>
</dd><dt id="bib-PRIVACY-BY-DESIGN">[PRIVACY-BY-DESIGN]</dt><dd>Ann Cavoukian, PhD. <a href="http://www.ipc.on.ca/images/Resources/7foundationalprinciples.pdf"><cite>Privacy By Design: The 7 Foundational Principles</cite></a>. August 2009, revised January 2011. URL: <a href="http://www.ipc.on.ca/images/Resources/7foundationalprinciples.pdf">http://www.ipc.on.ca/images/Resources/7foundationalprinciples.pdf</a>
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