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Peter Saint-Andre 2012-06-06 18:50:55 -06:00
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<abstract>This specification defines an XMPP protocol extension for communicating the reputation of any entity on the network.</abstract>
&LEGALNOTICE;
<number>0275</number>
<status>Deferred</status>
<status>Experimental</status>
<type>Standards Track</type>
<sig>Standards</sig>
<approver>Council</approver>
@ -21,6 +21,12 @@
<supersededby/>
<shortname>reputation</shortname>
&stpeter;
<revision>
<version>0.2</version>
<date>2012-06-06</date>
<initials>psa</initials>
<remark><p>Removed password strength as an account criterion; changed range from -128/+127 to -100/+100; aligned document somewhat (but not completely) with REPUTE work at the IETF.</p></remark>
</revision>
<revision>
<version>0.1</version>
<date>2010-01-21</date>
@ -36,24 +42,25 @@
</header>
<section1 topic='Introduction' anchor='intro'>
<p>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 &xep0045; rooms for low-reputation users, integration with &xep0016;, and the like.</p>
<p>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 faster blacklisting of rogue servers and other bad actors, differential quality of service based on reputation, delayed entry to &xep0045; rooms for low-reputation users, integration with &xep0016;, and the like.</p>
</section1>
<section1 topic='Terminology' anchor='terminology'>
<p>The following terms identify the entities mentioned in this document:</p>
<ul>
<li>Relying Party -- the entity that queries a Vouching Party about the reputation score of a Subject</li>
<li>Subject -- the entity whose reputation is vouched for by a Vouching Party</li>
<li>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.</li>
<li>Inquirer -- the entity that queries a Rater about the reputation score of a Subject</li>
<li>Rater -- an entity that maintains a reputation score about a Subject; a Rater might be a fellow IM user (e.g., a buddy in one's roster as defined in &xmppim;), the server to which a client connects, a peer server to which a server connects (see &xep0267;), or a specialized reputation service (similar to a DNSBL on the email network)</li>
<li>Subject -- the entity whose reputation is asserted by a Rater</li>
</ul>
</section1>
<section1 topic='Approach' anchor='approach'>
<p>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 &xmppim;), the server to which a client connects, a fellow server to which a server connects (see &xep0267;), 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 &xep0268; or as separate notifications.</p>
<p>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.</p>
<p>The approach taken here is that 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 +100), whereas bad behaviors will decrease a Subject's score (down to a minimum of -100). Any Inquirer can query any "Rater" about the reputation score of a Subject.</p>
<p>In the terms of &reputemodel; and &reputemedia;, this protocol defines only one reputation reponse set, where the rater is making an assertion about the overall reputation of an XMPP entity.</p>
<p>To determine reputation in an objective way, it is important to define the specific behaviors that can be 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 (naturally these criteria are not meant to be exhaustive).</p>
<section2 topic='Server Reputation' anchor='approach-server'>
<p>On the theory that it is more important to reward positive behavior than to punish negative behavior, we first define a number of criteria for increasing the reputation score of an XMPP server (naturally this list of criteria is not meant to be exclusive).</p>
<table caption='Positive Server Behaviors'>
<p>On the theory that it is more important to reward positive behavior than to punish negative behavior, we define a number of criteria for increasing the reputation score of an XMPP server, along with a few criteria for decreasing the reputation score.</p>
<table caption='Server Behaviors'>
<tr>
<th>Criterion</th>
<th>Suggested Point Value</th>
@ -91,7 +98,7 @@
<td>+5</td>
</tr>
<tr>
<td>Service answers &xep0030; information requests sent to bare JIDs, including identification of admin accounts and anonymous users.</td>
<td>Answers &xep0030; information requests sent to bare JIDs, including identification of admin accounts and anonymous users.</td>
<td>+5</td>
</tr>
<tr>
@ -106,13 +113,21 @@
<td>Admin factor (average of admins' reputation scores, divided by ten and rounded up).</td>
<td>Varies</td>
</tr>
<tr>
<td>Rate limiting (points per incident).</td>
<td>-5</td>
</tr>
<tr>
<td>Incident reports (points per validated report).</td>
<td>-10</td>
</tr>
</table>
<p>For example, a server that (1) meets all of the foregoing criteria, (2) has been online for 7 years, and (3) whose admins have an average score of 37 would have a reputation number of 15+5+5+5+5+5+5+5+5+5+4+21 = 85.</p>
<p>By constrast, a server that does not have a CA-issued cert, does not require CAPTCHAs for account registration, does not support incident reporting, does not support reputation scores, does not require TLS, does have SRV records (+10), has no website, does not answer service discovery requests about its users, has not verified the xmpp@domain.tld email address, has been online for 1 week, and whose administrators are unknown would have a reputation score of 10.</p>
<p>For example, a server that (1) meets all of the foregoing criteria, (2) has been online for 7 years, and (3) whose admins have an average score of 37 would have a reputation score of 15+5+5+5+5+5+5+5+5+5+4+21 = 85.</p>
<p>By constrast, a server that does not have a CA-issued cert, does not require CAPTCHAs for account registration, does not support incident reporting, does not support reputation scores, does not require TLS, does have SRV records (+10), has no website, does not answer service discovery requests about its users, has not verified the xmpp@domain.tld email address, has been online for 1 week, whose administrators are unknown, that has experienced 1 rate limiting incident, and that has been the subject of 2 incident reports would have a reputation score of -15.</p>
</section2>
<section2 topic='Account Reputation' anchor='approach-account'>
<p>The reputation associated with an XMPP account (typically but not always a user) is harder to quantify and easier to fake than server reputation. The following are some possible criteria.</p>
<table caption='Positive Account Behaviors'>
<table caption='Account Behaviors'>
<tr>
<th>Criterion</th>
<th>Suggested Point Value</th>
@ -137,10 +152,6 @@
<td>Verified website</td>
<td>+5</td>
</tr>
<tr>
<td>Password strength</td>
<td>Measured on a scale from 0 (e.g., "password") to 5</td>
</tr>
<tr>
<td>Reputation of buddies known to server</td>
<td>Divide average reputation by 10</td>
@ -162,24 +173,24 @@
<td>For each room in which the user is banned (XEP-0045 "outcast"), divide the room's reputation by 10 and decrement the user's score by the result (e.g., -6 for a room with a reputation of 60).</td>
</tr>
<tr>
<td>Rate limiting</td>
<td>For each rate limiting incident, -5.</td>
<td>Rate limiting (points per incident)</td>
<td>-5</td>
</tr>
<tr>
<td>Incident reports</td>
<td>For each validated incident report, -10.</td>
<td>Incident reports (points per validated report)</td>
<td>-10</td>
</tr>
</table>
<p>For example, an account that is an admin of a server (+15), has been online for 5 years (+25), has a verified email address (+5) and website (+5), has a strong password (+5), has a "buddy reputation average" of 40 (+4), uses a public key (+10), has passed a CAPTCHA test (+5), owns 3 chatrooms with an average reputation of 30 (+9), and has not been banned from any chatrooms, rate limited, or been the subject of any incident reports would have a reputation number of 83.</p>
<p>By contrast, an account that is registered (+5), was just created, has no verified email address or website, has a strong password (+5), has a "buddy reputation average" of 10 (+1), does not use a public key, has not passed a CAPTCHA test, owns or administers no chatrooms, has been banned from 3 chatrooms with an average reputation of 30 (-9), has been rate limited twice (-10), and has been the subject of 2 incident reports (-20) would have a reputation number of -28.</p>
<p>For example, an account that is an admin of a server (+15), has been online for 5 years (+25), has a verified email address (+5) and website (+5), has a "buddy reputation average" of 40 (+4), uses a public key (+10), has passed a CAPTCHA test (+5), owns 3 chatrooms with an average reputation of 30 (+9), and has not been banned from any chatrooms, rate limited, or been the subject of any incident reports would have a reputation score of 78.</p>
<p>By contrast, an account that is registered (+5), was just created, has no verified email address or website, has a "buddy reputation average" of 10 (+1), does not use a public key, has not passed a CAPTCHA test, owns or administers no chatrooms, has been banned from 3 chatrooms with an average reputation of 30 (-9), has been rate limited twice (-10), and has been the subject of 2 incident reports (-20) would have a reputation score of -25.</p>
</section2>
<section2 topic='Other Entities' anchor='approach-other'>
<p>Any entity can have a reputation score: servers, end-user accounts, chatrooms, chatroom servers, publish-subscribe servers, vouching services, etc. Criteria for entities other than servers and accounts are yet to be described.</p>
<p>Any entity can have a reputation score: servers, end-user accounts, chatrooms, chatroom servers, publish-subscribe servers, service directories (&xep0309;), third-party reputation services, etc. Criteria for entities other than servers and accounts are yet to be described.</p>
</section2>
</section1>
<section1 topic='Protocol' anchor='protocol'>
<p>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 &lt;score/&gt; element qualified by the 'urn:xmpp:reputation:0' namespace &VNOTE;.</p>
<p>In order to query a Rater about the reputation of a Subject, an Inquirer sends an IQ stanza of type "get" containing a &lt;score/&gt; element and 'jid' attribute qualified by the 'urn:xmpp:reputation:0' namespace &VNOTE;.</p>
<example caption='Score request'><![CDATA[
<iq from='juliet@capulet.lit/chamber'
to='shakespeare.lit'
@ -188,7 +199,7 @@
<score xmlns='urn:xmpp:reputation:0' jid='romeo@montague.lit'/>
</iq>
]]></example>
<p>The Vouching Party would then return an error or a score.</p>
<p>The Rater would then return an error or a score; if the latter, the &lt;score/&gt; element shall include both a 'jid' attribute and a 'num' attribute.</p>
<example caption='Score response'><![CDATA[
<iq from='shakespeare.lit'
to='juliet@capulet.lit/chamber'
@ -199,16 +210,20 @@
num='65'/>
</iq>
]]></example>
<p>Any XMPP error might be appropriate (e.g., &forbidden; if the Relying Party is not trusted at all by the Vouching Party).</p>
<p>Any XMPP error might be appropriate (e.g., &forbidden; if the Inquirer is not trusted at all by the Rater or &notfound; if the Rater has no score information about the Subject).</p>
</section1>
<section1 topic='Determining Support' anchor='support'>
<p>To advertise its support for reputation scores, when replying to &xep0030; information requests an entity MUST return a feature for 'urn:xmpp:reputation:0'.</p>
<p>To advertise its support for reputation scores, when replying to &xep0030; information requests an entity MUST return a feature of 'urn:xmpp:reputation:0'.</p>
<p>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 &xep0115;. However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.</p>
</section1>
<section1 topic='Internationalization Considerations' anchor='i18n'>
<p>The 'jid' attribute is a "JID slot" as described in &rfc6122bis;.</p>
</section1>
<section1 topic='Security Considerations' anchor='security'>
<p>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.</p>
<p>Any entity can keep a reputation score (i.e., be a Rater) for any other entity. Although Raters might be considered more knowledgeable than others, that judgment is up to the Inquirer and is not a feature of the network itself.</p>
</section1>
<section1 topic='IANA Considerations' anchor='iana'>
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<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:attribute name='num' type='ScoreNumber' use='optional'/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
<xs:simpleType name="ScoreNumber">
<xs:restriction base="xs:integer">
<xs:maxInclusive value="100" />
<xs:minInclusive value="-100" />
</xs:restriction>
</xs:simpleType>
</xs:schema>
]]></code>
</section1>