Network Working Group                                      Paul E. Jones
Internet Draft                                         Gonzalo Salgueiro
Intended status: Standards Track                           Cisco Systems
Expires: May 29, 2013                                       Joseph Smarr
                                                       November 29, 2012



   This specification defines the WebFinger protocol, which can be used
   to discover information about people or other entities on the
   Internet using standard HTTP methods.

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 May 29, 2013.

Copyright Notice

   Copyright (c) 2012 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
   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.

Jones, et al.            Expires May 29, 2013                   [Page 1]

Internet-Draft                WebFinger                    November 2012

Table of Contents

   1. Introduction...................................................2
   2. Terminology....................................................2
   3. Overview.......................................................3
   4. Example Use of WebFinger.......................................3
      4.1. Locating a User's Blog....................................3
      4.2. Identity Provider Discovery for OpenID Connect............5
      4.3. Auto-Configuration of Email Clients.......................6
      4.4. Retrieving Device Information.............................7
   5. WebFinger Protocol.............................................8
      5.1. Performing a WebFinger Query..............................8
      5.2. The JSON Resource Descriptor (JRD) Document...............9
      5.3. The "rel" Parameter.......................................9
      5.4. WebFinger and URIs.......................................11
   6. Cross-Origin Resource Sharing (CORS)..........................12
   7. Access Control................................................12
   8. Hosted WebFinger Services.....................................13
   9. Security Considerations.......................................13
   10. IANA Considerations..........................................15
   11. Acknowledgments..............................................15
   12. References...................................................15
      12.1. Normative References....................................15
      12.2. Informative References..................................16
   Author's Addresses...............................................17

1. Introduction

   WebFinger is used to discover information about people or other
   entities on the Internet using standard HTTP [2] methods.  The
   WebFinger server returns a structured document that contains link
   relations, properties, and/or other information that is suitable for
   automated processing.  For a person, the kinds of information that
   might be shared via WebFinger include a personal profile address,
   identity service, telephone number, or preferred avatar.  For other
   entities on the Internet, the server might return documents
   containing link relations that allow a client to discover the amount
   of toner in a printer or the physical location of a server.

   Information returned via WebFinger might be for direct human
   consumption (e.g., looking up someone's phone number), or it might be
   used by systems to help carry out some operation (e.g., facilitate
   logging into a web site by determining a user's identity service).

2. Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [1].

Jones, et al.            Expires May 29, 2013                   [Page 2]

Internet-Draft                WebFinger                    November 2012

   WebFinger makes heavy use of "Link Relations".  Briefly, a Link
   Relation is an attribute and value pair used on the Internet wherein
   the attribute identifies the type of link to which the associated
   value refers.  In Hypertext Transfer Protocol (HTTP) and Web Linking
   [4], the attribute is a "rel" and the value is an "href". WebFinger
   also uses the "rel" attribute, where the "rel" value is either a
   single IANA-registered link relation type [12] or a URI [6].

3. Overview

   WebFinger enables the discovery of information about users, devices,
   and other entities that are associated with a host.  Discovery
   involves a single HTTP GET request to the well-known [3] "webfinger"
   resource at the target host and receiving back a JavaScript Object
   Notation (JSON) [5] Resource Descriptor (JRD) document [11]
   containing link relations.  The request MUST include the URI or IRI
   [7] for the entity for which information is sought as a parameter
   named "resource".

   Use of WebFinger is illustrated in the examples in Section 4, then
   described more formally in Section 5.

4. Example Use of WebFinger

   This non-normative section shows a few sample uses of WebFinger.

4.1. Locating a User's Blog

   Assume you receive an email from Bob and he refers to something he
   posted on his blog, but you do not know where Bob's blog is located.
   It would be simple to discover the address of Bob's blog if he makes
   that information available via WebFinger.

   Assume your email client can discover the blog for you.  After
   receiving the message from Bob (bob@example.com), you instruct your
   email client to perform a WebFinger query.  It does so by issuing the
   following HTTPS query to example.com:

     GET /.well-known/webfinger?
                           resource=acct%3Abob%40example.com HTTP/1.1
     Host: example.com

   The server might then respond with a message like this:

     HTTP/1.1 200 OK
     Access-Control-Allow-Origin: *
     Content-Type: application/json; charset=UTF-8


Jones, et al.            Expires May 29, 2013                   [Page 3]

Internet-Draft                WebFinger                    November 2012

       "expires" : "2012-11-16T19:41:35Z",
       "subject" : "acct:bob@example.com",
       "aliases" :
       "properties" :
           "http://example.com/rel/role/" : "employee"
       "links" :
           "rel" : "http://webfinger.net/rel/avatar",
           "type" : "image/jpeg",
           "href" : "http://www.example.com/~bob/bob.jpg"
           "rel" : "http://webfinger.net/rel/profile-page",
           "href" : "http://www.example.com/~bob/"
           "rel" : "blog",
           "type" : "text/html",
           "href" : "http://blogs.example.com/bob/",
           "titles" :
               "en-us" : "The Magical World of Bob",
               "fr" : "Le monde magique de Bob"
           "rel" : "vcard",
           "href" : "http://www.example.com/~bob/bob.vcf"

   The email client would take note of the "blog" link relation in the
   above JRD document that refers to Bob's blog.  This URL would then be
   presented to you so that you could then visit his blog.  The email
   client might also note that Bob has published an avatar link relation
   and use that picture to represent Bob inside the email client.
   Lastly, the client might consider the vcard [14] link relation in
   order to update contact information for Bob.

   In the above example, an "acct" URI [8] is used in the query, though
   any valid alias for the user might also be used.  An alias is a URI
   that is different from the "subject" URI that identifies the same

Jones, et al.            Expires May 29, 2013                   [Page 4]

Internet-Draft                WebFinger                    November 2012

   entity.  In the above example, there is one "http" alias returned,
   though there might have been more than one.  Had the "http:" URI
   shown as an alias been used to query for information about Bob, the
   query would have appeared as:

     GET /.well-known/webfinger?
              resource=http%3A%2F%2Fwww.example.com%2F~bob%2F HTTP/1.1
     Host: example.com

   The response would have been substantially the same, with the subject
   and alias information changed as necessary.  Other information, such
   as the expiration time might also change, but the set of link
   relations and properties would be the same with either response.

4.2. Identity Provider Discovery for OpenID Connect

   Suppose Carol wishes to authenticate with a web site she visits using
   OpenID Connect [16].  She would provide the web site with her OpenID
   Connect identifier, say carol@example.com.  The visited web site
   would perform a WebFinger query looking for the OpenID Connect
   Provider.  Since the site is interested in only one particular link
   relation, the server might utilize the "rel" parameter as described
   in section 5.3:

     GET /.well-known/webfinger?
     Host: example.com

   The server might respond with a JSON Resource Descriptor document
   like this:

       "expires" : "2012-11-16T19:41:35Z",
       "subject" : "acct:carol@example.com",
       "aliases" :
       "properties" :
           "http://example.com/rel/role/" : "employee"
       "links" :
           "rel" : "http://openid.net/specs/connect/1.0/issuer",
           "href" : "https://openid.example.com/"

Jones, et al.            Expires May 29, 2013                   [Page 5]

Internet-Draft                WebFinger                    November 2012


   Since the "rel" parameter only filters the link relations returned by
   the server, other name/value pairs in the response, including any
   aliases or properties, would be returned.  Also, since support for
   the "rel" parameter is optional, the client must not assume the
   "links" array will contain only the requested link relation.

4.3. Auto-Configuration of Email Clients

   WebFinger could be used to auto-provision an email client with basic
   configuration data.  Suppose that sue@example.com wants to configure
   her email client.  Her email client might issue the following query:

     GET /.well-known/webfinger?
              resource=mailto%3Asue%40example.com HTTP/1.1
     Host: example.com

   The response from the server would contain entries for the various
   protocols, transport options, and security options.  If there are
   multiple options, the server might return a link relation that for
   each of the valid options and the client or Sue might select which
   option to choose.  Since JRD documents list link relations in a
   specific order, then the most-preferred choices could be presented
   first.  Consider this response:

     "subject" : "mailto:sue@example.com",
     "links" :
         "rel" : "http://example.net/rel/smtp-server",
         "properties" :
           "host" : "smtp.example.com",
           "port" : "587",
           "login-required" : "yes",
           "transport" : "starttls"
         "rel" : "http://example.net/rel/imap-server",
         "properties" :
           "host" : "imap.example.com",
           "port" : "993",
           "transport" : "ssl"

Jones, et al.            Expires May 29, 2013                   [Page 6]

Internet-Draft                WebFinger                    November 2012


   In this example, you can see that the WebFinger server advertises an
   SMTP service and an IMAP service.  In this example, the "href"
   entries associated with the link relation are absent.  This is valid
   when there is no external reference that needs to be made.

4.4. Retrieving Device Information

   As another example, suppose there are printers on the network and you
   would like to check the current toner level for a particular printer
   identified via the URI device:p1.example.com.  While the "device" URI
   scheme is not presently specified, we use it here for illustrative

   Following the procedures similar to those above, a query may be
   issued to get link relations specific to this URI like this:

     GET /.well-known/webfinger?resource=
                       device%3Ap1.example.com HTTP/1.1
     Host: example.com

   The link relations that are returned for a device may be quite
   different than those for user accounts.  Perhaps we may see a
   response like this:

     HTTP/1.1 200 OK
     Access-Control-Allow-Origin: *
     Content-Type: application/json; charset=UTF-8

       "subject" : "device:p1.example.com",
       "links" :
           "rel" : "http://example.com/rel/tipsi",
           "href" : ""

   While this example is fictitious, you can imagine that perhaps the
   Transport Independent, Printer/System Interface [15] may be enhanced
   with a web interface that allows a device that understands the TIP/SI
   web interface specification to query the printer for toner levels.

Jones, et al.            Expires May 29, 2013                   [Page 7]

Internet-Draft                WebFinger                    November 2012

5. WebFinger Protocol

   WebFinger is a simple HTTP-based web service that utilizes the JSON
   Resource Descriptor (JRD) document format and the Cross-Origin
   Resource Sharing (CORS) [10] specification.

   This specification defines URI parameters that are passed from the
   client to the server when issuing a request.  These parameters,
   "resource" and "rel", and the parameter values are included in the
   "query" component of the URI (see Section 3.4 of RFC 3986).  To
   construct the "query" component, the client performs the following
   steps.  First, each parameter value is percent-encoded as per Section
   2.1 of RFC 3986.  Next, the client constructs a string to be placed
   in the query component by concatenating the name of the first
   parameter together with an equal sign ("=") and the percent-encoded
   parameter value.  For any subsequent parameters, the client appends
   an ampersand ("&") to the string, the name of the next parameter, an
   equal sign, and percent-encoded parameter value.  The client MUST NOT
   insert any spaces while constructing the string.  The order in which
   the client places each parameter and its corresponding parameter
   value is unspecified.

5.1. Performing a WebFinger Query

   WebFinger clients issue queries to the well-known resource /.well-
   known/webfinger.  All queries MUST include the "resource" parameter
   exactly once and set to the value of the URI for which information is
   being sought.  If the "resource" parameter is absent or malformed,
   the WebFinger server MUST return a 400 status code.

   Clients MUST first attempt a query the server using HTTPS and utilize
   HTTP only if an HTTPS connection cannot be established.  If the HTTPS
   server has an invalid certificate or returns an HTTP status code
   indicating some error, including a 4xx or 5xx, the client MUST NOT
   use HTTP in attempt to complete the discovery.

   WebFinger servers MUST return JRD documents as the default
   representation for the resource.  A client MAY include the "Accept"
   header to indicate a desired representation, though no other
   representation is defined in this specification.  For the JRD
   document, the media type is "application/json" [5].

   If the client queries the WebFinger server and provides a URI for
   which the server has no information, the server MUST return a 404
   status code.

   WebFinger servers can include cache validators in a response to
   enable conditional requests by clients and/or expiration times as per
   RFC 2616 section 13.

Jones, et al.            Expires May 29, 2013                   [Page 8]

Internet-Draft                WebFinger                    November 2012

5.2. The JSON Resource Descriptor (JRD) Document

   The JSON Resource Descriptor (JRD) document is formally described in
   Appendix A of [11].  There is a RECOMMENDED order of JRD name/value
   pairs.  Further, WebFinger requires some name/value pairs and some
   are optional.  The following list indicates the preferred order and
   comments on the presence or absence of name/value pairs:

        o "expires" (name/value pair) is optional
        o "subject" (name/value pair) is required and MUST be the value
          of the "resource" parameter
        o "aliases" (array) is optional and absence or an empty array
          are semantically the same
        o "properties" (object) is optional and absence or an empty
          object are semantically the same
        o "links" (array) is optional and absence or an empty array are
          semantically the same

   Values within the "links" array are presented by the server in order
   of preference.

   The "links" array is comprised of several name/value pairs.  As
   above, the following list indicates the preferred order within a
   "links" array and comments on the presence or absence of name/value
   pairs within the array:

        o "rel" (name/value pair) is required
        o "type" (name/value pair) is optional
        o "href" (name/value pair) is optional
        o "template" (name/value pair) is forbidden
        o "titles" (object) is optional and absence or an empty object
          are semantically the same
        o "properties" (object) is optional and absence or an empty
          object are semantically the same

   Clients MUST ignore any unknown or forbidden name/value pair received
   in the JRD document.

5.3. The "rel" Parameter

   WebFinger defines the "rel" parameter to request only a subset of the
   information that would otherwise be returned without the "rel"
   parameter.  When the "rel" parameter is used, only the link relations
   that match the link relations provided via "rel" are included in the
   array of links returned in the JSON Resource Descriptor document.
   All other information normally present in a resource descriptor is
   present in the resource descriptor, even when "rel" is employed.

Jones, et al.            Expires May 29, 2013                   [Page 9]

Internet-Draft                WebFinger                    November 2012

   The "rel" parameter MAY be transmitted to the server multiple times
   in order to request multiple types of link relations.

   The purpose of the "rel" parameter is to return a subset of
   resource's link relations.  Use of the parameter might reduce
   processing requirements on either the client or server, and it might
   also reduce the bandwidth required to convey the partial resource
   descriptor, especially if there are numerous link relation values to
   convey for a given resource.

   Support for the "rel" parameter is OPTIONAL, but RECOMMENDED on the
   server.  Should the server not support the "rel" parameter, it MUST
   ignore it and process the request as if any "rel" parameter values
   were not present.

   The following example presents the same example as found in section
   4.1, but uses the "rel" parameter in order to select two link

     GET /.well-known/webfinger?
                rel=vcard HTTP/1.1
     Host: example.com

   In this example, the client requests the link relations of type
   "http://webfinger.net/rel/profile-page" and "vcard".  The server then
   responds with a message like this:

     HTTP/1.1 200 OK
     Access-Control-Allow-Origin: *
     Content-Type: application/json; charset=UTF-8

       "expires" : "2012-11-16T19:41:35Z",
       "subject" : "acct:bob@example.com",
       "aliases" :
       "properties" :
           "http://example.com/rel/role/" : "employee"
       "links" :
           "rel" : "http://webfinger.net/rel/profile-page",
           "href" : "http://www.example.com/~bob/"

Jones, et al.            Expires May 29, 2013                  [Page 10]

Internet-Draft                WebFinger                    November 2012

           "rel" : "vcard",
           "href" : "http://www.example.com/~bob/bob.vcf"

   As you can see, the server returned only the link relations requested
   by the client, but also included the other parts of the JSON resource
   Descriptor document.

   In the event that a client requests links for link relations that are
   not defined for the specified resource, a resource descriptor MUST be
   returned.  In the returned JRD, the "links" array MAY be absent,
   empty, or contain only links that did match a provided "rel" value.
   The server MUST NOT return a 404 status code when a particular link
   relation specified via "rel" is not defined for the resource, as a
   404 status code is reserved for indicating that the resource itself
   (e.g., either /.well-known/webfinger or the resource indicated via
   the "resource" parameter) does not exist.

5.4. WebFinger and URIs

   WebFinger requests can include a parameter specifying the URI of an
   account, device, or other entity.  WebFinger is agnostic regarding
   the scheme of such a URI: it could be an "acct" URI [7], an "http" or
   "https" URI, a "mailto" URI, or some other scheme.

   For resources associated with a user account at a host, use of the
   "acct" URI scheme is RECOMMENDED, since it explicitly identifies an
   account accessible via WebFinger.  Further, the "acct" URI scheme is
   not associated with other protocols as, by way of example, the
   "mailto" URI scheme is associated with email.  Since not every host
   offers email service, using the "mailto" URI scheme [9] is not ideal
   for identifying user accounts on all hosts.  That said, use of the
   "mailto" URI scheme would be ideal for use with WebFinger to discover
   mail server configuration information for a user.

   A host MAY utilize one or more URIs that serve as aliases for the
   user's account, such as URIs that use the "http" URI scheme [2].  A
   WebFinger server MUST return substantially the same response to both
   an "acct" URI and any alias URI for the account, including the same
   set of link relations and properties.  The only name/value pairs in
   the response that MAY be different include "subject", "expires", and
   "aliases".  In addition, the server SHOULD include the entire list
   aliases for the user's account in the JRD returned when querying the
   LRDD resource or when utilizing the "resource" parameter.

Jones, et al.            Expires May 29, 2013                  [Page 11]

Internet-Draft                WebFinger                    November 2012

6. Cross-Origin Resource Sharing (CORS)

   WebFinger resources might not be accessible from a web browser due to
   "Same-Origin" policies.  The current best practice is to make
   resources available to browsers through Cross-Origin Resource Sharing
   (CORS) [10], and servers MUST include the Access-Control-Allow-Origin
   HTTP header in responses.  Servers SHOULD support the least
   restrictive setting by allowing any domain access to the WebFinger

      Access-Control-Allow-Origin: *

   There are cases where defaulting to the least restrictive setting is
   not appropriate, for example a WebFinger server on an intranet that
   provides sensitive company information should not allow CORS requests
   from any domain, as that could allow leaking of that sensitive
   information.  WebFinger servers that wish to restrict access to
   information from external entities SHOULD use a more restrictive
   Access-Control-Allow-Origin header.

7. Access Control

   As with all web resources, access to the /.well-known/webfinger
   resource MAY require authentication.  Further, failure to provide
   required credentials MAY result in the server forbidding access or
   providing a different response than had the client authenticated with
   the server.

   Likewise, a server MAY provide different responses to different
   clients based on other factors, such as whether the client is inside
   or outside a corporate network.  As a concrete example, a query
   performed on the internal corporate network might return link
   relations to employee pictures, whereas link relations for employee
   pictures might not be provided to external entities.

   Further, link relations provided in a WebFinger server response MAY
   point to web resources that impose access restrictions.  For example,
   the aforementioned corporate server may provide both internal and
   external entities with URIs to employee pictures, but further
   authentication might be required in order for the client to access
   the picture resources if the request comes from outside the corporate

   The decisions made with respect to what set of link relations a
   WebFinger server provides to one client versus another and what
   resources require further authentication, as well as the specific
   authentication mechanisms employed, are outside the scope of this

Jones, et al.            Expires May 29, 2013                  [Page 12]

Internet-Draft                WebFinger                    November 2012

8. Hosted WebFinger Services

   As with most services provided on the Internet, it is possible for a
   domain owner to utilize "hosted" WebFinger services.  By way of
   example, a domain owner might control most aspects of their domain,
   but use a third-party hosting service for email.  In the case of
   email, mail servers for a domain are identified by MX records.  An MX
   record points to the mail server to which mail for the domain should
   be delivered.  It does not matter to the sending mail server whether
   those MX records point to a server in the destination domain or a
   different domain.

   Likewise, a domain owner might utilize the services of a third party
   to provide WebFinger services on behalf of its users.  Just as a
   domain owner was required to insert MX records into DNS to allow for
   hosted email serves, the domain owner is required to redirect HTTP(S)
   queries to its domain to allow for hosted WebFinger services.

   When a query is issued to /.well-known/webfinger, the web server MUST
   return a 301, 302, or 307 response status code that includes a
   Location header pointing to the location of the hosted WebFinger
   service URL.  The WebFinger service URL does not need to point to
   /.well-known/* on the hosting service provider server.  WebFinger
   clients MUST follow all 301, 302, or 307 redirection requests.

   As an example, assume that example.com's WebFinger services are
   hosted by example.net.  Suppose a client issues a query for
   acct:alice@example.com like this:

     GET /.well-known/webfinger?
                   resource=acct%3Aalice%40example.com HTTP/1.1
     Host: example.com

   The server might respond with this:

     HTTP/1.1 307 Temporary Redirect
     Location: http://wf.example.net/example.com/webfinger?
                       resource=acct%3Aalice%40example.com HTTP/1.1

   The client MUST follow the redirection, re-issuing the request to the
   URL provided in the Location header.

9. Security Considerations

   Since this specification utilizes Cross-Origin Resource Sharing
   (CORS) [10], all of the security considerations applicable CORS are
   also applicable to this specification.

Jones, et al.            Expires May 29, 2013                  [Page 13]

Internet-Draft                WebFinger                    November 2012

   The recommended use of HTTPS is to ensure that information is not
   modified during transit.  It should be appreciated that in
   environments where an HTTPS server is normally available, there
   exists the possibility that a compromised network might have its
   WebFinger server operating on HTTPS replaced with one operating only
   over HTTP.  As such, clients that need to ensure data is not
   compromised SHOULD NOT issue queries over a non-secure connection.
   While Section 5.1 allows for clients that fail to establish an HTTPS
   connection to attempt a query using HTTP, a client and any underlying
   client libraries are not required to re-issue queries using HTTP and
   SHOULD NOT when security for a given application that uses WebFinger
   is paramount.

   When using HTTPS, clients MUST verify that the certificate used on an
   HTTPS connection is valid.

   Service providers and users should be aware that placing information
   on the Internet accessible through WebFinger means that any user can
   access that information.  While WebFinger can be an extremely useful
   tool for allowing quick and easy access to one's avatar, blog, or
   other personal information, users should understand the risks, too.
   If one does not wish to share certain information with the world, do
   not allow that information to be freely accessible through WebFinger
   and do not use any service supporting WebFinger.  Further, WebFinger
   servers MUST NOT be used to provide any personal information to any
   party unless explicitly or implicitly authorized by the person whose
   information is being shared. Implicit authorization can be determined
   by the user's voluntary utilization of a service as defined by that
   service's relevant terms of use or published privacy policy.

   The aforementioned word of caution is perhaps worth emphasizing again
   with respect to dynamic information one might wish to share, such as
   the current location of a user.  WebFinger can be a powerful tool
   used to assemble information about a person all in one place, but
   service providers and users should be mindful of the nature of that
   information shared and the fact that it might be available for the
   entire world to see.  Sharing location information, for example,
   would potentially put a person in danger from any individual who
   might seek to inflict harm on that person.

   The easy access to user information via WebFinger was a design goal
   of the protocol, not a limitation.  If one wishes to limit access to
   information available via WebFinger, such as a WebFinger server for
   use inside a corporate network, the network administrator must take
   measures necessary to limit access from outside the network.  Using
   standard methods for securing web resources, network administrators
   do have the ability to control access to resources that might return
   sensitive information.  Further, WebFinger servers can be employed in

Jones, et al.            Expires May 29, 2013                  [Page 14]

Internet-Draft                WebFinger                    November 2012

   such a way as to require authentication and prevent disclosure of
   information to unauthorized entities.

   Finally, a WebFinger server has no means of ensuring that information
   provided by a user is accurate.  Likewise, neither the server nor the
   client can be absolutely guaranteed that information has not been
   manipulated either at the server or along the communication path
   between the client and server.  Use of HTTPS helps to address some
   concerns with manipulation of information along the communication
   path, but it clearly cannot address issues where the server provided
   incorrect information, either due to being provided false information
   or due to malicious behavior on the part of the server administrator.
   As with any information service available on the Internet, users
   should wary of information received from untrusted sources.

10. IANA Considerations

   This specification registers the "webfinger" well-known URI in the
   Well-Known URI Registry as defined by [3].

   URI suffix:  webfinger

   Change controller:  IETF

   Specification document(s):  RFC QQQ

   Related information:  The JSON Resource Descriptor (JRD) documents
   obtained via the WebFinger web service are described in RFC 6415
   Appendix A and RFC QQQ.

   [RFC EDITOR: Please replace "QQQ" references in this section with the
   number for this RFC.]

11. Acknowledgments

   The authors would like to acknowledge Eran Hammer-Lahav, Blaine Cook,
   Brad Fitzpatrick, Laurent-Walter Goix, Joe Clarke, Michael B. Jones,
   Peter Saint-Andre, Dick Hardt, Tim Bray, and Joe Gregorio for their
   invaluable input.

12. References

12.1. Normative References

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

Jones, et al.            Expires May 29, 2013                  [Page 15]

Internet-Draft                WebFinger                    November 2012

   [2]   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.

   [3]   Nottingham, M., Hammer-Lahav, E., "Defining Well-Known Uniform
         Resource Identifiers (URIs)", RFC 5785, April 2010.

   [4]   Nottingham, M., "Web Linking", RFC 5988, October 2010.

   [5]   Crockford, D., "The application/json Media Type for
         JavaScript Object Notation (JSON)", RFC 4627, July 2006.

   [6]   Berners-Lee, T., Fielding, R., and Masinter, L., "Uniform
         Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
         January 2005.

   [7]   Duerst, M., "Internationalized Resource Identifiers (IRIs)",
         RFC 3987, January 2005.

   [8]   Saint-Andre, P., "The 'acct' URI Scheme", draft-ietf-appsawg-
         acct-uri-01, October 2012.

   [9]   Duerst, M., Masinter, L., and J. Zawinski, "The 'mailto' URI
         Scheme", RFC 6068, October 2010.

   [10]  Van Kesteren, A., "Cross-Origin Resource Sharing", W3C CORS
         http://www.w3.org/TR/cors/, July 2010.

   [11]  Hammer-Lahav, E. and Cook, B., "Web Host Metadata", RFC 6415,
         October 2011.

12.2. Informative References

   [12]  IANA, "Link Relations", http://www.iana.org/assignments/link-

   [13]  Zimmerman, D., "The Finger User Information Protocol", RFC
         1288, December 1991.

   [14]  Perreault, S., "vCard Format Specification", RFC 6350, August

   [15]  "Transport Independent, Printer/System Interface", IEEE Std
         1284.1-1997, 1997.

   [16]  Sakimura, N., Bradley, J., Jones, M., de Medeiros, B.,
         Mortimore, C., and E. Jay, "OpenID Connect Messages 1.0", June
         2012, http://openid.net/specs/openid-connect-messages-1_0.html.

Jones, et al.            Expires May 29, 2013                  [Page 16]

Internet-Draft                WebFinger                    November 2012

Author's Addresses

   Paul E. Jones
   Cisco Systems, Inc.
   7025 Kit Creek Rd.
   Research Triangle Park, NC 27709

   Phone: +1 919 476 2048
   Email: paulej@packetizer.com
   IM: xmpp:paulej@packetizer.com

   Gonzalo Salgueiro
   Cisco Systems, Inc.
   7025 Kit Creek Rd.
   Research Triangle Park, NC 27709

   Phone: +1 919 392 3266
   Email: gsalguei@cisco.com
   IM: xmpp:gsalguei@cisco.com

   Joseph Smarr

   Email: jsmarr@google.com

Jones, et al.            Expires May 29, 2013                  [Page 17]