XEP-0275: Entity Reputation

WARNING: Consideration of this document has been Deferred by the XMPP Standards Foundation. Implementation of the protocol described herein is not recommended.

Table of Contents

1. Introduction

Reputation systems are used in many online communities to increase trust and to encourage communication, commerce, and other forms of interaction. The public XMPP network might benefit from instituting a reputation system for servers, for end users, or both. The benefits might include fast blacklisting of rogue servers and other bad actors, differential quality of service based on reputation, delayed entry to Multi-User Chat [1] rooms for low-reputation users, integration with Privacy Lists [2], and the like.

2. Terminology

The following terms identify the entities mentioned in this document:

• Relying Party -- the entity that queries a Vouching Party about the reputation score of a Subject
• Subject -- the entity whose reputation is vouched for by a Vouching Party
• Vouching Party -- an entity that maintains a reputation score about a Subject, such as a server vouching for an account, a server vouching for a chatroom at a chat service associated with the server, a third party vouching service, etc.

3. Approach

The approach taken here is that an XMPP entity (a "Subject") is innocent until proven guilty, so it starts out with a score of zero. Good behaviors will increase a Subject's score (up to a maximum of +127), whereas bad behaviors will decrease a Subject's score (potentially down to a minimum of -128). Any entity (a "Relying Party") can query another entity (a "Vouching Party") about the reputation score of a Subject. A Vouching Party might be a fellow IM user (e.g., a buddy in one's roster as defined in XMPP IM [3]), the server to which a client connects, a fellow server to which a server connects (see Server Buddies [4]), or a specialized reputation service (similar to a DNSBL on the email network). Changes in reputation scores can also be sent in real time to Relying Parties, either as part of Incident Reporting [5] or as separate notifications.

To determine reputation in an objective way, it is important to define the specific behaviors that are used as measurable dimensions of good or bad reputation. The following sections attempt to do so for XMPP servers and XMPP users, with some rough point values.

4. Protocol

In order to query a Vouching Party about the reputation of a Subject, a Relying Party sends an IQ stanza of type "get" containing a <score/> element qualified by the 'urn:xmpp:reputation:0' namespace (see Namespace Versioning regarding the possibility of incrementing the version number).

Example 1. Score request

<iq from='juliet@capulet.lit/chamber'
    to='shakespeare.lit'
    id='bn4c297j'
    type='get'>
  <score xmlns='urn:xmpp:reputation:0' jid='romeo@montague.lit'/>
</iq>
  

The Vouching Party would then return an error or a score.

Example 2. Score response

<iq from='shakespeare.lit'
    to='juliet@capulet.lit/chamber'
    id='bn4c297j'
    type='result'>
  <score xmlns='urn:xmpp:reputation:0' 
         jid='romeo@montague.lit'
         num='65'/>
</iq>
  

Any XMPP error might be appropriate (e.g., <forbidden/> if the Relying Party is not trusted at all by the Vouching Party).

5. Determining Support

To advertise its support for reputation scores, when replying to Service Discovery [9] information requests an entity MUST return a feature for 'urn:xmpp:reputation:0'.

In order for an application to determine whether an entity supports this protocol, where possible it SHOULD use the dynamic, presence-based profile of service discovery defined in Entity Capabilities [10]. However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.

6. Security Considerations

Any entity can keep a reputation score for any other entity. Although some entities might be considered more knowledgeable than others, that judgment is up to the entity that makes a request for a reputation score and is not a feature of the network itself.

7. IANA Considerations

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [11].

8. XMPP Registrar Considerations

9. XML Schema

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='urn:xmpp:reputation:0'
    xmlns='urn:xmpp:reputation:0'
    elementFormDefault='qualified'>

  <xs:element name='score'>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base='xs:string'>
          <xs:attribute name='jid' type='xs:string' use='required'/>
          <xs:attribute name='num' type='xs:byte' use='optional'/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

</xs:schema>
  

10. Acknowledgements

Thanks to Dan Brickley, Kevin Smith, Mike Taylor, and Matthew Wild for their feedback.

Appendices

Appendix A: Document Information

Series: XEP
Number: 0275
Publisher: XMPP Standards Foundation
Status: Deferred
Type: Standards Track
Version: 0.1
Last Updated: 2010-01-21
Approving Body: XMPP Council
Dependencies: XMPP Core
Supersedes: None
Superseded By: None
Short Name: reputation
Source Control: HTML
This document in other formats: XML  PDF

Appendix B: Author Information

Appendix C: Legal Notices

Appendix D: Relation to XMPP

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 3920) and XMPP IM (RFC 3921) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself.

Appendix E: Discussion Venue

The primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list.

Discussion on other xmpp.org discussion lists might also be appropriate; see <http://xmpp.org/about/discuss.shtml> for a complete list.

Errata can be sent to <editor@xmpp.org>.

Appendix F: Requirements Conformance

The following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL".

Appendix G: Notes

Appendix H: Revision History

Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/

END