XMPP Working Group P. Saint-Andre Internet-Draft Jabber Software Foundation Expires: June 29, 2004 December 30, 2003 End-to-End Object Encryption in the Extensible Messaging and Presence Protocol (XMPP) draft-ietf-xmpp-e2e-07 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on June 29, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This memo defines a method for end-to-end object signing and encryption in the Extensible Messaging and Presence Protocol (XMPP). Saint-Andre Expires June 29, 2004 [Page 1] Internet-Draft XMPP E2E December 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Securing Messages . . . . . . . . . . . . . . . . . . . . . . 5 4. Securing Presence . . . . . . . . . . . . . . . . . . . . . . 6 5. Securing Arbitrary XMPP Data . . . . . . . . . . . . . . . . . 8 6. Rules for S/MIME Generation and Handling . . . . . . . . . . . 9 7. Secure Communications Through a Gateway . . . . . . . . . . . 12 8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 Normative References . . . . . . . . . . . . . . . . . . . . . 14 Informative References . . . . . . . . . . . . . . . . . . . . 16 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 16 A. Schema for urn:ietf:params:xml:ns:xmpp-e2e . . . . . . . . . . 16 B. Revision History . . . . . . . . . . . . . . . . . . . . . . . 17 Intellectual Property and Copyright Statements . . . . . . . . 19 Saint-Andre Expires June 29, 2004 [Page 2] Internet-Draft XMPP E2E December 2003 1. Introduction This memo define a method for end-to-end signing and encryption in the Extensible Messaging and Presence Protocol (XMPP). (For information about XMPP, see [XMPP-CORE] and [XMPP-IM].) The method defined herein enables a sender to encrypt and/or sign an instant message sent to a specific recipient, encrypt and/or sign presence information that is directed to a specific user, and sign presence information that is broadcasted to a specific user. This memo thereby helps the XMPP specifications meet the requirements defined in [IMP-REQS]. 1.1 Terminology This document inherits terminology defined in [SMIME], [IMP-MODEL], [CMS], and [XMPP-CORE]. The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [TERMS]. 1.2 Discussion Venue The authors welcome discussion and comments related to the topics presented in this document. The preferred forum is the mailing list, for which archives and subscription information are available at . 1.3 Intellectual Property Notice This document is in full compliance with all provisions of Section 10 of RFC 2026. Parts of this specification use the term "jabber" for identifying namespaces and other protocol syntax. Jabber[tm] is a registered trademark of Jabber, Inc. Jabber, Inc. grants permission to the IETF for use of the Jabber trademark in association with this specification and its successors, if any. 2. Requirements For the purposes of this memo, we stipulate the following requirements: 1. The method defined MUST address encryption and signing requirements for minimal instant messaging and presence only, as those are defined in [IMP-REQS]. The method is NOT REQUIRED to support non-IM applications of XMPP, nor to support advanced Saint-Andre Expires June 29, 2004 [Page 3] Internet-Draft XMPP E2E December 2003 instant messaging and presence functionality that is outside the scope of [IMP-REQS]. In particular, the method MUST address the following requirements defined in [IMP-REQS]: * The protocol MUST provide means to ensure confidence that a received message (NOTIFICATION or INSTANT MESSAGE) has not been corrupted or tampered with. (Section 2.5.1) * The protocol MUST provide means to ensure confidence that a received message (NOTIFICATION or INSTANT MESSAGE) has not been recorded and played back by an adversary. (Section 2.5.2) * The protocol MUST provide means to ensure that a sent message (NOTIFICATION or INSTANT MESSAGE) is only readable by ENTITIES that the sender allows. (Section 2.5.3) * The protocol MUST allow any client to use the means to ensure non-corruption, non-playback, and privacy, but the protocol MUST NOT require that all clients use these means at all times. (Section 2.5.4) * When A establishes a SUBSCRIPTION to B's PRESENCE INFORMATION, the protocol MUST provide A means of verifying the accurate receipt of the content B chooses to disclose to A. (Section 5.1.4) * The protocol MUST provide A means of verifying that the presence information is accurate, as sent by B. (Section 5.3.1) * The protocol MUST provide A means of ensuring that no other PRINCIPAL C can see the content of M. (Section 5.4.6) * The protocol MUST provide A means of ensuring that no other PRINCIPAL C can tamper with M, and B means to verify that no tampering has occurred. (Section 5.4.7) 2. The method defined MUST enable interoperability with non-XMPP messaging systems that support the Common Presence and Instant Messaging (CPIM) specifications defined by the Instant Messaging and Presence (IMPP) Working Group. Therefore: * Prior to encrypting or signing, the format of an instant message MUST conform to the CPIM Message Format defined in [MSGFMT]. * Prior to encrypting or signing, the format of presence Saint-Andre Expires June 29, 2004 [Page 4] Internet-Draft XMPP E2E December 2003 information MUST conform to the CPP Presence Information Data Format defined in [PIDF]. 3. The method MUST follow the required procedures (including the specific algorithms) defined in [CPIM] and [CPP]. In particular, these documents specify: * Encryption MUST use [SMIME] encryption with [CMS] EnvelopeData. * Signing MUST use [SMIME] signatures with [CMS] SignedData. 4. In order to enable interoperable implementations, sending and receiving applications MUST implement the algorithms defined under Section 6.9. 3. Securing Messages In order to encrypt a message, a sending entity MUST use the following procedure: 1. Generate a "Message/CPIM" object as defined in [MSGFMT]. 2. Encrypt and/or sign both the headers and content of the "Message/ CPIM" object as specified in Requirement 3 of Section 2 above. 3. Provide the resulting multipart [SMIME] object (see [MULTI]) within a CDATA section of an child of a stanza, where the element is qualified by the 'urn:ietf:params:xml:ns:xmpp-e2e' namespace. Example 1: Sender generates "Message/CPIM" object: Content-type: Message/CPIM From: Juliet Capulet To: Romeo Montague DateTime: 2003-12-09T11:45:36.66Z Subject: Imploring Content-type: text/plain; charset=utf-8 Content-ID: <1234567890@example.com> Wherefore art thou, Romeo? Example 2: Sender generates signed message (the 'from' address on the XMPP message stanza is stamped by sender's server): Saint-Andre Expires June 29, 2004 [Page 5] Internet-Draft XMPP E2E December 2003 To: Romeo Montague DateTime: 2003-12-09T23:45:36.66Z Subject: Imploring Content-type: text/plain; charset=utf-8 Content-ID: <1234567890@example.com> Wherefore art thou, Romeo? --next Content-Type: application/pkcs7-signature Content-Disposition: attachment;handling=required;filename=smime.p7s [signed body part] --next-- ]]> 4. Securing Presence In order to encrypt presence information, a sending entity MUST use the following procedure: 1. Generate an "application/pidf+xml" object as defined in [PIDF]. 2. Encrypt and/or sign the "application/pidf+xml" object as specified in Requirement 3 of Section 2 above. 3. Provide the resulting [SMIME] object within a CDATA section of an child of a stanza, where the element is qualified by the 'urn:ietf:params:xml:ns:xmpp-e2e' namespace. The stanza MUST include a 'to' attribute, i.e., it must be an instance of directed presence as defined in [XMPP-IM]. Saint-Andre Expires June 29, 2004 [Page 6] Internet-Draft XMPP E2E December 2003 Example 3: Sender generates "application/pidf+xml" object: open away retired to the chamber 2003-12-09T23:53:11.31 Example 4: Sender generates signed presence (the 'from' address on the XMPP presence stanza is stamped by sender's server): open away retired to the chamber 2003-12-09T23:53:11.31Z --next Content-Type: application/pkcs7-signature Content-Disposition: attachment;handling=required;filename=smime.p7s [signed body part] Saint-Andre Expires June 29, 2004 [Page 7] Internet-Draft XMPP E2E December 2003 --next-- ]]> 5. Securing Arbitrary XMPP Data The foregoing sections of this memo describe how to secure "least common denominator" messaging and presence data of the kind that can be directly translated into the MSGFMT or PIDF formats. However, XMPP possesses a third base-level stanza type () in addition to and , as well as the ability to include extended XML data within arbitrary child elements of the three core stanza types. Therefore it would be desirable to secure such data if possible. Because [MSGFMT] specifies the ability to encapsulate any MIME type, the approach taken in this memo is to include arbitrary XMPP data in a new MIME type, "application/xmpp+xml". The root element for this MIME type is , and the root element MUST contain one and only one child element, corresponding to one of the XMPP stanza types (i.e., message, presence, or iq) if the default namespace is 'jabber:client' or 'jabber:server' as defined in [XMPP-CORE]. The following examples illustrate the structure of the "application/ xmpp+xml" MIME type. Example 5: Message stanza with extended data contained in "application/xmpp+xml" MIME type: I told him what I thought, and told no more Than what he found himself was apt and true. Example 6: Presence stanza with extended data contained in "application/xmpp+xml" MIME type: Saint-Andre Expires June 29, 2004 [Page 8] Internet-Draft XMPP E2E December 2003 dnd Fomenting dissension Example 7: IQ stanza with extended data contained in "application/ xmpp+xml" MIME type: Stabber 666 FiendOS 6. Rules for S/MIME Generation and Handling 6.1 Certificate Enrollment [SMIME] does not specify how to obtain a certificate from a certificate authority, but instead mandates that every sending agent must already have a certificate. The PKIX Working Group has, at the time of this writing, produced two separate standards for certificate enrollment: [CMP] and [CMC]. Which method to use for certificate enrollment is outside the scope of this memo. 6.2 Certificate Retrieval A receiving agent MUST provide some certificate retrieval mechanism in order to gain access to certificates for recipients of digital envelopes. This memo does not cover how S/MIME agents handle certificates, only what they do after a certificate has been validated or rejected. S/MIME certification issues are covered in [CERT]. At a minimum, for initial S/MIME deployment, a user agent could Saint-Andre Expires June 29, 2004 [Page 9] Internet-Draft XMPP E2E December 2003 automatically generate a message to an intended recipient requesting that recipient's certificate in a signed return message. Receiving and sending agents SHOULD also provide a mechanism to allow a user to "store and protect" certificates for correspondents in such a way so as to guarantee their later retrieval. 6.3 Certificate Names End-entity certificates used by XMPP entities in the context of this memo SHOULD contain a valid instant messaging and presence address. The address SHOULD be specified as both an 'im:' URI (for instant messaging, as defined in [CPIM]) and a 'pres:' URI (for presence, as defined in [CPP]); each of these URIs SHOULD be specified in a separate GeneralName entry of type uniformResourceIdentifier inside the subjectAltName (i.e., two separate entries). Information in the subject distinguished name SHOULD be ignored. Each URI MUST be of the form or , where the "address" portion is an XMPP address (also referred to as a Jabber Identifier or JID) as defined in [XMPP-CORE], prepended with the 'im:' or 'pres:' URI scheme. The address SHOULD be of the form (i.e., a "bare JID"), although any valid JID form MAY be used. The value of the JID contained in the XMPP 'from' attribute SHOULD match the JID provided in the signer's certificate, with the exception that the resource identifier portion of the JID contained in the 'from' attribute SHOULD be ignored for matching purposes. Receiving agents SHOULD check that sending JID matches a JID provided in the signer's certificate, with the exception that the resource identifier portion of the JID contained in the 'from' attribute MAY be ignored for matching purposes. A receiving agent SHOULD provide some explicit alternate processing of the message if this comparison fails, which may be to display a message that shows the recipient the addresses in the certificate or other certificate details. The subject alternative name extension is used in S/MIME as the preferred means to convey the instant messaging and presence address that corresponds to the entity for this certificate. Any instant messaging or presence address present in the certificate SHOULD be encoded using the otherName choice of the subjectAltName type along with a type-id of "xmpp" (as these terms are profiled in [X509]). 6.4 Transfer Encoding Because it is expected that XMPP applications will not interface with older 7-bit systems, the transfer encoding (as defined in Section Saint-Andre Expires June 29, 2004 [Page 10] Internet-Draft XMPP E2E December 2003 3.1.2 of [SMIME]) MUST be "binary". 6.5 Attachment of Signatures Sending agents SHOULD attach a signature to each encrypted message or presence stanza. If a signature is attached, a Content-Disposition header field (as defined in [DISP]) SHOULD be included to specify how the signature is to be handled by the receiving application. 6.6 Inclusion of Certificates If the sender and recipient are involved in an active messaging session over a period of time, the sending agent SHOULD include the sender's certificate along with at least one encrypted message stanza every five minutes. Outside the context of an active messaging session, the sending agent SHOULD include the sender's certificate along with each encrypted message stanza. A sending agent MAY include the sender's certificate along with each encrypted presence stanza. However, a sending agent SHOULD NOT include a certificate more than once every five minutes. 6.7 Order of Signing and Encrypting If a stanza is both signed and encrypted, it SHOULD be signed first, then encrypted. 6.8 Checking of Timestamps Timestamps are included in "Message/CPIM" and "application/pidf+xml" objects to help prevent replay attacks. All timestamps MUST conform to [DATETIME] and be presented as UTC with no offset, including fractions of a second as appropriate. Absent a local adjustment to the sending application's perceived time or the underlying clock time, the sending application MUST ensure that the timestamps it sends to the receiver increase monotonically (if necessary by incrementing the seconds fraction in the timestamp if the clock returns the same time for multiple requests). The following rules apply to the receiving application: o it MUST verify that the timestamp received is within five minutes of the current time o it SHOULD verify that the timestamp received is greater than any timestamp received in the last 10 minutes which passed the previous check o if any of the foregoing checks fails, the timestamp SHOULD be presented to the receiving entity (human or via an API) marked as Saint-Andre Expires June 29, 2004 [Page 11] Internet-Draft XMPP E2E December 2003 "old timestamp", "future timestamp", or "decreasing timestamp" 6.9 Mandatory to Implement Technologies At a minimum, all implementations MUST support the following CMS algorithms as defined in [CMS-ALG]: for digest: SHA-1 for signing: RSA for content encryption: AES 7. Secure Communications Through a Gateway A common method for achieving interoperability between two disparate services is through the use of a "gateway" that interprets the protocols of each service and translates them into the protocols of the other. The CPIM specifications (specifically [MSGFMT] and [PIDF] define the common profiles to be used for interoperability between instant messaging and presence services that comply with [IMP-REQS]. In the case of communications between an XMPP service and a non-XMPP service, we can visualize this relationship as follows: +-------------+ +-------------+ +------------+ | | | | | | | XMPP | | XMPP-CPIM | | Non-XMPP | | Service | <----> | Gateway | <----> | Service | | | | | | | +-------------+ +-------------+ +------------+ The end-to-end encryption method defined herein enables the exchange of encrypted and/or signed instant messages and presence through an XMPP-CPIM gateway. In particular: o When a gateway receives a secured XMPP message or presence stanza from the XMPP service that is addressed to a user on the non-XMPP service, it MUST remove the XMPP "wrapper" (everything down to and including the and tags) in order to reveal the multipart S/MIME object, then route the object to the non-XMPP service (first wrapping it in the protocol used by the non-XMPP service if necessary). o When a gateway receives a secured non-XMPP instant message or presence document from the non-XMPP service that is addressed to a user on the XMPP service, it MUST remove the non-XMPP "wrapper" Saint-Andre Expires June 29, 2004 [Page 12] Internet-Draft XMPP E2E December 2003 (if any) in order to reveal the multipart S/MIME object, wrap the object in an XMPP message or presence "wrapper" (including the and tags), and then route the XMPP stanza to the XMPP service. The wrapped S/MIME object MUST be immutable and MUST NOT be modified by an XMPP-CPIM gateway. 8. Security Considerations This entire memo discusses security. Detailed security considerations for instant messaging and presence protocols are given in [IMP-REQS] (Sections 5.1 through 5.4), and for XMPP in particular are given in [XMPP-CORE] (Sections 12.1 through 12.6). The end-to-end security method defined here MAY result in exchanging secured instant messages and presence information through a gateway that implements the CPIM specifications. Such a gateway MUST be compliant with the minimum security requirements of the instant messaging and presence protocols with which it interfaces. 9. IANA Considerations 9.1 Content-type Registration for "application/xmpp+xml" To: ietf-types@iana.org Subject: Registration of MIME media type application/xmpp+xml MIME media type name: application MIME subtype name: xmpp+xml Required parameters: (none) Optional parameters: charset Indicates the character encoding of the enclosed XML; the default encoding is UTF-8. Encoding considerations: Contains XML, which can employ 8-bit characters, depending on the character encoding used. Security considerations: Contains a message, presence information, or IQ (request-response) data in XMPP, which may be considered private. Appropriate precautions should be adopted to limit disclosure of this information. Saint-Andre Expires June 29, 2004 [Page 13] Internet-Draft XMPP E2E December 2003 Interoperability considerations: (none) Specification: XXXX Applications which use this media type: XMPP-compliant instant messaging and presence systems. Additional information: (none) Person and email address to contact for further information: IETF, XMPP Working Group, Intended usage: COMMON Author/Change controller: IETF, XMPP Working Group 9.2 XML Namespace Name for e2e Data in XMPP A URN sub-namespace for signed and encrypted content in the Extensible Messaging and Presence Protocol (XMPP) is defined as follows. (This namespace name adheres to the format defined in [XML-REG].) URI: urn:ietf:params:xml:ns:xmpp-e2e Specification: XXXX Description: This is the XML namespace name for signed and encrypted content in the Extensible Messaging and Presence Protocol as defined by XXXX. Registrant Contact: IETF, XMPP Working Group, Normative References [CERT] Ramsdell, B., "S/MIME Version 3 Certificate Handling", RFC 2632, June 1999. [CMC] Blaze, M., Ioannidis, J. and A. Keromytis, "DSA and RSA Key and Signature Encoding for the KeyNote Trust Management System", RFC 2792, March 2000. [CMP] Adams, C. and S. Farrell, "Internet X.509 Public Key Infrastructure Certificate Management Protocols", RFC 2510, March 1999. [CMS] Housley, R., "Cryptographic Message Syntax (CMS)", RFC Saint-Andre Expires June 29, 2004 [Page 14] Internet-Draft XMPP E2E December 2003 3369, August 2002. [CMS-ALG] Housley, R., "Cryptographic Message Syntax (CMS) Algorithms", RFC 3370, August 2002. [CPIM] Crocker, D. and J. Peterson, "Common Profile for Instant Messaging (CPIM)", draft-ietf-impp-im-03 (work in progress), May 2003. [CPP] Crocker, D. and J. Peterson, "Common Profile for Presence (CPP)", draft-ietf-impp-pres-03 (work in progress), May 2003. [DATETIME] Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, July 2002. [DISP] Troost, R., Dorner, S. and K. Moore, "Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field", RFC 2183, August 1997. [IMP-MODEL] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000, . [IMP-REQS] Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging / Presence Protocol Requirements", RFC 2779, February 2000. [MSGFMT] Atkins, D. and G. Klyne, "Common Presence and Instant Messaging: Message Format", draft-ietf-impp-cpim-msgfmt-08 (work in progress), January 2003. [MULTI] Galvin, J., Murphy, S., Crocker, S. and N. Freed, "Security Multiparts for MIME: Multipart/Signed and Multipart/Encrypted", RFC 1847, October 1995. [PIDF] Fujimoto, S., Sugano, H., Klyne, G., Bateman, A., Carr, W. and J. Peterson, "Presence Information Data Format", draft-ietf-impp-cpim-pidf-08 (work in progress), May 2003. [SMIME] Ramsdell, B., "S/MIME Version 3 Message Specification", RFC 2633, June 1999. [TERMS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Saint-Andre Expires June 29, 2004 [Page 15] Internet-Draft XMPP E2E December 2003 [X509] Housley, R., Polk, W., Ford, W. and D. Solo, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 3280, April 2002. [XMPP-CORE] Saint-Andre, P., "XMPP Core", draft-ietf-xmpp-core-21 (work in progress), December 2003. [XMPP-IM] Saint-Andre, P., "XMPP Instant Messaging", draft-ietf-xmpp-im-20 (work in progress), December 2003. Informative References [XML-REG] Mealling, M., "The IANA XML Registry", draft-mealling-iana-xmlns-registry-05 (work in progress), June 2003. [XMPP-CPIM] Saint-Andre, P., "Mapping the Extensible Messaging and Presence Protocol (XMPP) to Common Presence and Instant Messaging (CPIM)", draft-ietf-xmpp-cpim-03 (work in progress), November 2003. Author's Address Peter Saint-Andre Jabber Software Foundation EMail: stpeter@jabber.org Appendix A. Schema for urn:ietf:params:xml:ns:xmpp-e2e The following XML schema is descriptive, not normative. Saint-Andre Expires June 29, 2004 [Page 16] Internet-Draft XMPP E2E December 2003 Appendix B. Revision History Note to RFC Editor: please remove this entire appendix, and the corresponding entries in the table of contents, prior to publication. B.1 Changes from draft-ietf-xmpp-e2e-06 o Specified use of SHA-1 for digest and AES for content encryption. o Specified order of signing then encrypting. o Specified format and checking of timestamps. o Clarified use of subjectAltName field, where the GeneralName content is a URI of the form im:user@host and pres:user@host. o Clarified circumstances under which certificates should be attached. o Added Content-Disposition header field to examples. B.2 Changes from draft-ietf-xmpp-e2e-05 o Addressed I-D nits and RFC Editor formatting. B.3 Changes from draft-ietf-xmpp-e2e-04 o Added text about instant inbox addresses. B.4 Changes from draft-ietf-xmpp-e2e-03 o Specified that S/MIME multipart objects are enclosed in a CDATA section. o Changed "text/xml" to "text/plain" for message examples. o Specified must-implement technologies, transfer encodings, certificate enrollment, certificate retrieval, and certificate names (including subjectAltName for JIDs). o Specified requirements regarding attachment of signatures and inclusion of certificates. o Fixed some small terminological errors. Saint-Andre Expires June 29, 2004 [Page 17] Internet-Draft XMPP E2E December 2003 B.5 Changes from draft-ietf-xmpp-e2e-02 o Completely revised to use formats defined in the CPIM specifications, S/MIME only, etc. B.6 Changes from draft-ietf-xmpp-e2e-01 o Removed old Section 6 (Signalling Support via Presence) -- the ability to sign broadcasted presence made it redundant. o Made small editorial changes to address RFC Editor requirements. B.7 Changes from draft-ietf-xmpp-e2e-00 o Added support for all stanza types. o Specified that the full stanza is encrypted. o Added support for S/MIME in addition to OpenPGP. o Specified that encrypted presence must be directed to a specific recipient. o Specified order of encrypting and signing. o Added support for signing broadcasted presence. o Added IANA considerations. o Changed namespace to 'urn:ietf:params:xml:ns:xmpp-e2e'. o Added XML schema. Saint-Andre Expires June 29, 2004 [Page 18] Internet-Draft XMPP E2E December 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. 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This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION Saint-Andre Expires June 29, 2004 [Page 19] Internet-Draft XMPP E2E December 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Saint-Andre Expires June 29, 2004 [Page 20]