mirror of
https://github.com/moparisthebest/xeps
synced 2024-11-22 17:22:23 -05:00
468 lines
18 KiB
XML
468 lines
18 KiB
XML
<?xml version='1.0' encoding='UTF-8'?>
|
|
<!DOCTYPE xep SYSTEM 'xep.dtd' [
|
|
<!ENTITY % ents SYSTEM 'xep.ent'>
|
|
<!ENTITY tls13 "<span class='ref'><link url='https://tools.ietf.org/html/draft-ietf-tls-tls13-21'>draft-ietf-tls-tls13-21</link></span> <note>The Transport Layer Security (TLS) Protocol Version 1.3 <<link url='https://tools.ietf.org/html/draft-ietf-tls-tls13-21'>https://tools.ietf.org/html/draft-ietf-tls-tls13-21</link>>.</note>" >
|
|
<!ENTITY sasl-ht "<span class='ref'><link url='https://tools.ietf.org/html/draft-schmaus-kitten-sasl-ht-03'>draft-schmaus-sasl-ht-03</link></span><note>draft-schmaus-sasl-ht-03: The Hashed Token SASL Mechanism <<link url='https://tools.ietf.org/html/draft-schmaus-kitten-sasl-ht-03'>https://tools.ietf.org/html/draft-schmaus-kitten-sasl-ht-03</link>>.</note>" >
|
|
%ents;
|
|
]>
|
|
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
|
|
<xep>
|
|
<header>
|
|
<title>Instant Stream Resumption</title>
|
|
|
|
<abstract>This specification introduces a mechanism for instant
|
|
stream resumption, based on Stream Management (XEP-0198), allowing
|
|
XMPP entities to instantaneously resume an XMPP stream.</abstract>
|
|
&LEGALNOTICE;
|
|
<number>xxxx</number>
|
|
<status>ProtoXEP</status>
|
|
<type>Standards Track</type>
|
|
<sig>Standards</sig>
|
|
<approver>Council</approver>
|
|
<dependencies>
|
|
<spec>XMPP Core</spec>
|
|
<spec>XEP-0198</spec>
|
|
<spec>XEP-0388</spec>
|
|
</dependencies>
|
|
<supersedes/>
|
|
<supersededby/>
|
|
<shortname>isr</shortname>
|
|
<author>
|
|
<firstname>Florian</firstname>
|
|
<surname>Schmaus</surname>
|
|
<email>flo@geekplace.eu</email>
|
|
<jid>flo@geekplace.eu</jid>
|
|
</author>
|
|
<revision>
|
|
<version>0.0.5</version>
|
|
<date>2017-11-30</date>
|
|
<initials>fs</initials>
|
|
<remark><p>Minor changes</p></remark>
|
|
</revision>
|
|
<revision>
|
|
<version>0.0.4</version>
|
|
<date>2017-10-15</date>
|
|
<initials>fs</initials>
|
|
<remark>
|
|
<ul>
|
|
<li>Bump SASL2 namespace to urn:xmpp:sasl:1, and as result:</li>
|
|
<li>Rename 'key' to 'token'</li>
|
|
</ul>
|
|
</remark>
|
|
</revision>
|
|
<revision>
|
|
<version>0.0.3</version>
|
|
<date>2017-03-17</date>
|
|
<initials>fs</initials>
|
|
<remark><p>Based ISR on SASL2.</p></remark>
|
|
</revision>
|
|
<revision>
|
|
<version>0.0.2</version>
|
|
<date>2016-03-11</date>
|
|
<initials>fs</initials>
|
|
<remark><p>Second draft.</p></remark>
|
|
</revision>
|
|
<revision>
|
|
<version>0.0.1</version>
|
|
<date>2016-02-12</date>
|
|
<initials>fs</initials>
|
|
<remark><p>First draft.</p></remark>
|
|
</revision>
|
|
</header>
|
|
|
|
<section1 topic='Introduction' anchor='intro'>
|
|
|
|
<p>This XEP specifies an instant stream resumption mechanism based
|
|
on &xep0198;, allowing XMPP entities to instantaneously resume an
|
|
XMPP stream. This can be seen as the complementary part to &xep0305;
|
|
allowing for fast XMPP session (re-)establishment.</p>
|
|
|
|
<p>Compared to the existing stream resumption mechanism of <link
|
|
url='http://xmpp.org/extensions/xep-0198.html#resumption'><cite>XEP-0198</cite>
|
|
§ 5</link>, the approach defined herein reduces the round trips
|
|
required to resume a stream to exactly <em>one</em>. This is
|
|
achieved by using just a secure short-lived token to resume the
|
|
stream.</p>
|
|
|
|
</section1>
|
|
|
|
<section1 topic='Glossary' anchor='glossary'>
|
|
|
|
<dl>
|
|
<di>
|
|
<dt>ISR</dt>
|
|
<dd>Instant Stream Resumption.</dd>
|
|
</di>
|
|
<di>
|
|
<dt>Instant Stream Resumption Token (ISR Token)</dt>
|
|
<dd>A shared secret that is exclusively ephemeral and represented as string.</dd>
|
|
</di>
|
|
<di>
|
|
<dt>TLS</dt>
|
|
<dd>Transport Layer Security (&rfc5246;).</dd>
|
|
</di>
|
|
</dl>
|
|
|
|
</section1>
|
|
|
|
<!--
|
|
<section1 topic='Use Cases' anchor='usecases'>
|
|
<p>STRONGLY RECOMMENDED.</p>
|
|
</section1>
|
|
-->
|
|
|
|
<section1 topic='Stream Feature'>
|
|
|
|
<p>XMPP entities providing Instant Stream Resumption MUST announce
|
|
that functionality as stream feature, but only if an instant stream
|
|
resumption is possible at this stage. The ISR stream future consists
|
|
of an <isr/> element qualified by the 'htpps://xmpp.org/extensions/isr/0'
|
|
namespace. And since ISR requires TLS, this means that the
|
|
<isr/> stream feature only appears on TLS secured
|
|
connections.</p>
|
|
|
|
<p>The ISR stream feature element MUST contain a <mechanisms/>
|
|
element as defined in &rfc6120;. This element contains the SASL
|
|
mechanism which are available to be used for instant stream
|
|
resumption.</p>
|
|
|
|
<example caption='Server announces the Instant Stream Resumption Stream Feature'><![CDATA[
|
|
<stream:stream
|
|
from='example.com'
|
|
xmlns='jabber:client'
|
|
xmlns:stream='http://etherx.jabber.org/stream'
|
|
version='1.0'>
|
|
|
|
<stream:features>
|
|
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/>
|
|
<sm xmlns='urn:xmpp:sm:3'/>
|
|
<isr xmlns='https://xmpp.org/extensions/isr/0'>
|
|
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
|
|
<mechanism>HT-SHA-256-ENDP</mechanism>
|
|
</mechaisms>
|
|
</isr>
|
|
</stream:features>
|
|
]]></example>
|
|
|
|
<p>Every ISR enabled entity SHOULD support the HT-SHA-256-ENDP
|
|
mechanism, support for HT-SHA-256-UNIQ is RECOMMENDED. The family
|
|
of <cite>HT SASL</cite> mechanisms is specified in &sasl-ht;.</p>
|
|
|
|
</section1>
|
|
|
|
<section1 topic='Obtaining a Instant Stream Resumption Token' anchor='obtain'>
|
|
|
|
<p>In order to obtain an ISR token, the requesting entity must add an
|
|
'isr-enable' element qualified by the 'htpps://xmpp.org/extensions/isr/0' namespace to the
|
|
<enable/> element as defined in &xep0198; when attempting to
|
|
enable Stream Management. This <isr-enable/> element MUST contain a
|
|
'mechanism' attribute containing the name of the SASL mechanism the
|
|
requesting entity will use when performing ISR with the returned
|
|
token. The entities involved in ISR MUST only use or allow this
|
|
mechanism when performing ISR with the according token. This
|
|
effectively pins the SASL mechanism <note>Pinning the SASL mechanism
|
|
is believed to increase the security</note>.</p>
|
|
|
|
<example caption='An <enable/> Nonza with the ISR 'mechanism' element'><![CDATA[
|
|
<enable xmlns='urn:xmpp:sm:3'>
|
|
<isr-enable xmlns='https://xmpp.org/extensions/isr/0' mechanism='HT-SHA-256-ENDP'/>
|
|
</enable>
|
|
]]></example>
|
|
|
|
<p>Next, the <enabled/> Nonza (see &xep0360;) which is send as
|
|
positive reply upon a request to enable Stream Management, MUST
|
|
contain an 'isr-enabled' element qualified by the 'htpps://xmpp.org/extensions/isr/0'
|
|
namespace containing a ISR token as value of its 'token' attribute. The
|
|
token MUST be newly generated by a cryptographically secure random
|
|
number generator and MUST contain at least 128 bit of entropy. The
|
|
<isr-enabled/> element can optionally also contain a
|
|
'location' attribute
|
|
which specifies the preferred IP address or hostname, and a TCP port
|
|
number of the host which should be used for instant stream
|
|
resumption.</p>
|
|
|
|
<example caption='An <enabled/> Nonza with a ISR token'><![CDATA[
|
|
<enabled xmlns='urn:xmpp:sm:3'>
|
|
<isr-enabled xmlns='https://xmpp.org/extensions/isr/0' token='a0b9162d-0981-4c7d-9174-1f55aedd1f52'/>
|
|
</enabled>]]></example>
|
|
|
|
<example caption='An <enabled/> Nonza with a ISR token and location'><![CDATA[
|
|
<enabled xmlns='urn:xmpp:sm:3'>
|
|
<isr-enabled xmlns='https://xmpp.org/extensions/isr/0'
|
|
token='a0b9162d-0981-4c7d-9174-1f55aedd1f52'
|
|
location='isr.example.org:5222'/>
|
|
</enabled>]]></example>
|
|
|
|
<p>The <enabled/> Nonza containing an ISR token MUST only be
|
|
sent over TLS secured connections.</p>
|
|
|
|
</section1>
|
|
|
|
<section1 topic='Instant Stream Resumption' anchor='isr'>
|
|
|
|
<p>In order to instantaneously resume an XMPP stream the initiating
|
|
entity, which is either an XMPP client or server, must posses a
|
|
valid ISR token. After it has obtained the ISR token, using the process
|
|
described in the previous section, it first determines the host for
|
|
resumption, and after that, tries to perform the instant stream
|
|
resumption.</p>
|
|
|
|
<section2 topic='Determing the Host for Resumption' anchor='host'>
|
|
|
|
<p>The lookup mechanism order to determine host candidates for ISR
|
|
resumption is as follows:</p>
|
|
|
|
<ol>
|
|
<li>The host provided in the optional 'location' attribute
|
|
qualified by the 'htpps://xmpp.org/extensions/isr/0' namespace found in the
|
|
<enabled/> element of <cite>XEP-0198</cite> (the
|
|
"isr:location").
|
|
</li>
|
|
<li>The hosts determined by means of &xep0368;.</li>
|
|
<li>The host announced in the 'location' attribute of the
|
|
<enabled/> Nonza defined in <cite>XEP-0198</cite>.</li>
|
|
<li>Standard host lookup mechanisms.</li>
|
|
</ol>
|
|
|
|
<p>The host candidates retrieved by those mechanisms SHOULD be
|
|
tried by the initiating entity in this order.</p>
|
|
|
|
<p>Note that the hosts announced by the 'location' attribute
|
|
qualified by the 'htpps://xmpp.org/extensions/isr/0' namespace MUST be connected to
|
|
using TLS from the beginning, i.e. <starttls/> MUST NOT be
|
|
used, instead the TLS handshake is performed right after
|
|
establishing the connection.</p>
|
|
|
|
<p>This order prefers hosts which allow connections where TLS is
|
|
enabled from the beginning. This is desirable to reduce the
|
|
required round trips by skipping the <starttls/> step.</p>
|
|
|
|
</section2>
|
|
|
|
<section2 topic='Performing Instant Stream Resumption' anchor='resume'>
|
|
|
|
<p>After the remote host on which the instant stream resumption
|
|
should be performed was determined, the initiating entity connects
|
|
to the host, and establishes TLS by either</p>
|
|
|
|
<ol>
|
|
<li>establishing a TLS session right away, or</li>
|
|
<li>performing STARTTLS (&rfc6120; § 5).</li>
|
|
</ol>
|
|
|
|
<p>Now the initiating entity sends an XMPP <stream> open
|
|
element followed by a <authenticate/> Nonza as specified in
|
|
the &xep0388;. The initiating entity must also provide a
|
|
<inst-resume/> element qualified by the 'htpps://xmpp.org/extensions/isr/0'
|
|
namespace, which must contain a <resume/> element as defined
|
|
in &xep0198;.</p>
|
|
|
|
<p>If the with-isr-token' attribute is set to 'false', then the
|
|
SASL mechanism is performed as when traditionally authenticating
|
|
the XMPP session. If the value of the attribute is 'true', which is
|
|
the default value for this attribute, then the "password" given to
|
|
the SASL mechanism is the ISR token. Note that this implies that only
|
|
SASL mechanisms which take a password/token can be used this
|
|
way.</p>
|
|
|
|
<example caption='Initiating entity requests instant stream resumption via the Extensible SASL Profile (XEP-0388)'><![CDATA[
|
|
<?xml version='1.0'?>
|
|
<stream:stream
|
|
from='juliet@im.example.com'
|
|
to='im.example.com'
|
|
version='1.0'
|
|
xml:lang='en'
|
|
xmlns='jabber:client'
|
|
xmlns:stream='http://etherx.jabber.org/streams'>
|
|
|
|
<authenticate xmlns='urn:xmpp:sasl:1' mechanism='HT-SHA-256-ENDP'>
|
|
<initial-response>[base64 encoded SASL data]</initial-response>
|
|
<inst-resume xmlns='https://xmpp.org/extensions/isr/0' with-isr-token='true'/>
|
|
<resume xmlns='urn:xmpp:sm:3'
|
|
h='some-sequence-number'
|
|
previd='some-long-sm-id'/>
|
|
</inst-resume>
|
|
</authenticate>
|
|
]]></example>
|
|
|
|
<p>Note that the initiating entity SHOULD pipeline the instant
|
|
stream resumption request together with then initial
|
|
<stream> open element. The initiating entity is able to do
|
|
so since it already knows that the service supports ISR because it
|
|
announced an ISR token.</p>
|
|
|
|
<p>Servers MUST destroy the ISR token of a stream after an instant
|
|
stream resumption was attempted for that stream with an invalid ISR
|
|
token. Server implementations MUST implement the ISR token comparision in
|
|
linear runtime.</p>
|
|
|
|
<section3 topic='Successful Stream Resumption' anchor='isr-success'>
|
|
|
|
<example caption='Successful Instant Stream Resumption'><![CDATA[
|
|
<success xmlns='urn:xmpp:sasl:1'>z
|
|
<additional-data></additional-data>
|
|
<inst-resumed xmlns='https://xmpp.org/extensions/isr/0'
|
|
token='006b1a29-c549-41c7-a12c-2a931822f8c0'>
|
|
<resumed xmlns='urn:xmpp:sm:3' h='354' previd='123'/>
|
|
</inst-resumed>
|
|
</success>
|
|
]]></example>
|
|
|
|
<p>On success the server replies with a <success/> nonza as
|
|
specified in the &xep0388;, which must include a
|
|
<inst-resumed/> element qualified by the 'htpps://xmpp.org/extensions/isr/0'
|
|
namespace. This element MUST contain a <em>new</em> ISR Token found in
|
|
the 'token' attribute. It also MUST include a <resumed/> as
|
|
specified in &xep0198; containing the sequence number of the last by
|
|
Stream Management handled stanza in the 'h' attribute and the
|
|
'previd' attribute.</p>
|
|
|
|
<p>In case of an successful Instant Stream Resumption authenticated
|
|
by an ISR token, the server MUST immediately destroy the ISR token after
|
|
authentication, i.e., it MUST no longer be possible to perform an
|
|
ISR using that ISR token and Stream Management ID (SM-ID, see
|
|
&xep0198;) tuple.</p>
|
|
|
|
<p>After the <inst-resumed/> was received and has been
|
|
verified both entities MUST consider the resumed stream to be
|
|
re-established. This includes all previously negotiated stream
|
|
features like &xep0138;. It does however not include the specific
|
|
state of the features: For example in case of Stream Compression,
|
|
the dictionary used by the compression mechanism of the resumed
|
|
stream MUST NOT be considered to be restored after instant stream
|
|
resumption.</p>
|
|
|
|
<p class='box'>Note that this behavior is different from &xep0198;
|
|
stream resumption, where "outer stream" features like compression
|
|
are not restored. Since such a behavior would be counterproductive
|
|
towards the goal of this XEP, it specifies that the negotiation
|
|
state of such "outer stream" features is also restored (besides the
|
|
features which where already negotiated at ISR-time, i.e. TLS).</p>
|
|
|
|
</section3>
|
|
|
|
<section3 topic='Successful Authentication but failed Stream Resumption' anchor='isr-auth-success-resumption-failed'>
|
|
|
|
<p>If the server was able to authenticate the initiating entity
|
|
but is unable to resume the stream instantly it MUST reply with a
|
|
<success/> Nonza as defined in the &xep0388; containing
|
|
a <inst-resume-failed/> element qualified by the
|
|
'htpps://xmpp.org/extensions/isr/0' namespace. This
|
|
<inst-resume-failed/> MUST contain a <failed/>
|
|
element as defined in &xep0198;.</p>
|
|
|
|
<example caption='Server indicates instant stream resumption failure'><![CDATA[
|
|
<success xmlns='urn:xmpp:sasl:1'>
|
|
<inst-resume-failed xmlns='https://xmpp.org/extensions/isr/0'>
|
|
<failed xmlns='urn:xmpp:sm:3'
|
|
h='another-sequence-number'>
|
|
<item-not-found xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
|
|
</failed>
|
|
</inst-resume-failed>
|
|
</sucess>
|
|
]]></example>
|
|
|
|
<p>Instant stream resumption errors SHOULD be considered
|
|
recoverable, the initiating entity MAY continue with normal
|
|
session establishment; however, misuse of stream management MAY
|
|
result in termination of the stream. Since the initiating entity is
|
|
authenticated, it could continue with resource binding by using
|
|
&rfc6120; § 7. or &xep0386;.</p>
|
|
|
|
</section3>
|
|
|
|
<section3 topic='Multi step authentication ISR' anchor='multi-step-auth-isr'>
|
|
|
|
<p>As specified in the &xep0388; § 2.6.3, sole SASL authentication
|
|
may not be sufficient for authentication. In this case, the remote
|
|
entity sends a <continue/> element as defined in &xep0388;
|
|
to request the local entity to perform another
|
|
task.</p>
|
|
|
|
<example caption='Server requires Multi SASL Mechanism ISR'><![CDATA[
|
|
<continue xmlns='urn:xmpp:sasl:1'>
|
|
<additional-data>
|
|
T3B0aW9uYWwgQmFzZSA2NCBlbmNvZGVkIFNBU0wgc3VjY2VzcyBkYXRh
|
|
</additional-data>
|
|
<tasks>
|
|
<task>HOTP-EXAMPLE</task>
|
|
<task>TOTP-EXAMPLE</task>
|
|
<tasks>
|
|
</continue>
|
|
]]></example>
|
|
|
|
</section3>
|
|
|
|
<section3 topic='Failed ISR Authentication' anchor='isr-auth-failed'>
|
|
|
|
<p>If the server is unable to authenticate the initiating entity
|
|
it replies with a <failure/> Nonza as defined in
|
|
&xep0388;. The server MUST delete any state of the stream which
|
|
was attempted to resume in case the SM-ID was correct but the
|
|
authentication failed.<note>This is to prevent brute force
|
|
attacks.</note></p>
|
|
|
|
<example caption='Server indicates instant stream resumption failure'><![CDATA[
|
|
<failure xmlns='urn:xmpp:sasl:1'>
|
|
<not-authorized xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
|
|
</failure>
|
|
]]></example>
|
|
|
|
<p>After the ISR authentication has failed, the initiating entity
|
|
could continue with normal authentication (&xep0388;,
|
|
…).</p>
|
|
|
|
</section3>
|
|
|
|
</section2>
|
|
|
|
</section1>
|
|
|
|
<section1 topic='Security Considerations' anchor='security'>
|
|
|
|
<p>Any ISR data SHALL NOT be part of <cite>TLS 1.3</cite> 0-RTT
|
|
early data. (TODO: Shall we weaken this requirement to allow early
|
|
data?. It would be technically possible if the sender does not add
|
|
additional data, for example Stanzas, after the ISR/XEP-0388 data at
|
|
the end of the early data. And if the receiver does ensure that the
|
|
existence of such additional data is causing an ISR failure.)</p>
|
|
|
|
<p>It is of vital importance that the Instant Stream Resumption
|
|
Token is generated by a cryptographically secure random
|
|
generator. See &rfc4086; for more information about Randomness
|
|
Requirements for Security.</p>
|
|
|
|
</section1>
|
|
|
|
<section1 topic='IANA Considerations' anchor='iana'>
|
|
|
|
<p>This document requires no interaction with &IANA;.</p>
|
|
|
|
</section1>
|
|
|
|
<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
|
|
|
|
<p>The ®ISTRAR; includes 'htpps://xmpp.org/extensions/isr/0' in its registry of protocol namespaces (see &NAMESPACES;).</p>
|
|
|
|
</section1>
|
|
|
|
<section1 topic='XML Schema' anchor='schema'>
|
|
|
|
<p>TODO: Add after the XEP leaves the 'experimental' state.</p>
|
|
|
|
</section1>
|
|
|
|
<section1 topic='Acknowledgements' anchor='acknowledgements'>
|
|
|
|
<p>Thanks to Jonas Wielicki, Thijs Alkemade, Dave Cridland, Maxime
|
|
Buquet, Alexander Würstlein and Sam Whited for their feedback.</p>
|
|
|
|
</section1>
|
|
|
|
</xep>
|
|
|
|
<!-- Local Variables: -->
|
|
<!-- fill-column: 100 -->
|
|
<!-- indent-tabs-mode: nil -->
|
|
<!-- End: -->
|