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RFC 2542         Terminology and Goals for Internet Fax       March 1999


   facsimile messages suggests {3} that the standard accommodate
   arbitrary bit sequences.

5.2 Goals for transmission

   It is necessary {1} that Internet Fax to work in the context of the
   current Internet, Intranet, and the combination across firewalls.

   A single protocol with various extensions is preferable {3} to
   multiple separate protocols, if there are devices that might require,
   at different times and for different recipients, different protocols.

5.3 Goals for addressing

   Interoperability with the terminal types in section 2 requires {1}
   the ability to address each of the kinds of recipient devices.  The
   address of a recipient must give sufficient information to allow the
   sender to initiate communication.

   Interoperability with offramps to legacy fax terminals requires {1}
   that the message contain some way of addressing the final destination
   of facsimile messages, including telephone numbers, various ISDN
   addressing modes, and facsimile sub-addresses.

   Interoperability with Internet Mail requires {1} that it be possible
   to address Internet Fax to any email address.  Interworking with
   Internet mail also requires {1} that the addressing is in the email
   addressing headers, including mail transport envelope [RFC1123] and
   RFC822 headers, as appropriate. The information must {1} appear
   nowhere else.

   Sending devices might not have local storage for directories of
   addresses, and addresses might be cumbersome for users to type in.
   For these reasons, Internet Fax devices may require configuration to
   locate directories of recipients and their capabilities.

   The source of a fax message must {1} be clearly identified. The
   address of the appropriate return message (whether via fax or via
   email) should {2} be clearly identified in a way that is visible to
   all manner of recipients.  In the case of Internet Fax delivered by
   email, it should {2} be possible to use the normal 'reply' functions
   for email to return a message to the sender.

   Traditionally, it is common for the first page of a fax message sent
   to a facsimile terminal to contain an (image) representation of the
   name, address, return number, etc. of the sender of the document.
   Some legal jurisdictions for facsimile require an identification of
   the sender on every page. The standard for Internet Fax should {2}



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RFC 2542         Terminology and Goals for Internet Fax       March 1999


   cover the issues of sender and recipient identification in the cases
   where fax messages are re-routed, forwarded, sent through gateways.

5.4 Goals for Security

   Users typically use GSTN-based fax for confidential document
   transmission, assuming a similar or higher level of confidentiality
   and protection from both deliberate and inadvertent eavesdropping as
   holds for telephone conversations; the higher level of
   confidentiality arising from the requirement for non-standard
   equipment to intercept and interpret an overheard fax transmission.

   Similarly, in traditional fax there is an expectation (and, in some
   contexts, a legally recognized assurance) that the received fax is
   unaltered from the document originally transmitted.

   It is important {2} that Internet Fax give users a level of assurance
   for privacy and integrity that is as good or better than that
   available for telephone-based fax.  The Internet Fax standard should
   {2} specify how secure messages can be sent, in an interoperable
   fashion. The Internet Fax protocol should {2} encourage the
   introduction of security features, e.g., by requiring that minimum
   capability devices still accept signed messages (even if ignoring the
   signature.)

   In the case where the sender is responsible for payment for offramp
   services in a remote location, it is desirable {3} to provide for
   authentication and authorization of the sender, as well as enable
   billing related information from the offramp to be transferred
   securely.

5.5 Goals for capabilities exchange

   Traditional fax supports a wide range of devices, including high
   resolution ("Superfine"); recent enhancements include methods for
   color and a variety of compression mechanisms. Fax messaging includes
   the capability for "non-standard frames", which allow vendors to
   introduce proprietary data formats. In addition, facsimile supports
   "binary file transfer": a method of sending arbitrary binary data in
   a fax message.

   To support interoperability with these mechanisms, it should {2} be
   possible to express a wide variety of fax capabilities.

   Capability support has three elements: expression of the capabilities
   of the sender (as far as a particular message is concerned),
   expressing the capabilities of a recipient (in advance of the
   transmission of the message), and then the protocol by which



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RFC 2542         Terminology and Goals for Internet Fax       March 1999


   capabilities are exchanged.

   The Internet Fax standard should {2} specify a uniform mechanism for
   capabilities expression. If capabilities are being sent at times
   other than the time of message transmission, then capabilities should
   {2} include sufficient information to allow it to be validated,
   authenticated, etc.

   The Internet Fax standard may {3} include one or several methods for
   transmission, storage, or distribution of capabilities.

   A request for capability information, if sent to a recipient at any
   time other than the immediate time of delivery of the message, should
   {2} clearly identify the sender, the recipient whose capabilities are
   being requested, and the time of the request. Som kind of signature
   would be useful, too.

   A capability assertion (sent from recipient to sender) should {2}
   clearly identify the recipient and some indication of the date/time
   or range of validity of the information inside. To be secure,
   capability assertions should {2} be protected against interception
   and the substitution of valid data by invalid data.

6. Security Considerations

   This document describes the goals for the Internet Fax protocol,
   including the security goals. An Internet Fax protocol must {1}
   address the security goals and provide adequate measures to provide
   users with expected security features.

7. Acknowledgements

   The author gratefully acknowledges the contributions of Graham Klyne,
   Vivian Cancio, Dan Wing, Jim Dahmen, Neil Joffe, Mike Lake, Lloyd
   McIntyre, Richard Shockey, Herman Silbiger, Nadesan Narenthiran,
   George Pajari and Dave Crocker for their valuable comments on this
   document.

8. Author's Address

   Larry Masinter
   Xerox Corporation
   3333 Coyote Hill Road
   Palo Alto, CA 94304

   http://www.parc.xerox.com/masinter
   Fax: [phone]
   EMail: [e-mail]



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RFC 2542         Terminology and Goals for Internet Fax       March 1999


9. References

   [T.30]    "Procedures for Document Facsimile Transmission in the
             General Switched Telephone Network", ITU-T (CCITT),
             Recommendation T.30, July, 1996.

   [F.185]   "Internet facsimile: Guidelines for the support of the
             communication of facsimile documents", ITU-T (CCITT),
             Recommendation F.185, 1998.

   [T.37]    "Procedures for the transfer of facsimile data via store-
             and-forward on the Internet", ITU-T (CCITT), Recommendation
             T.37, 1998.

   [T.38]    "Procedures for real time Group 3 facsimile communication
             between terminals using IP Networks", ITU-T (CCITT),
             Recommendation T.38, 1998.

   [RFC2305] Toyoda, K., Ohno, H., Murai, J. and D. Wing, "A Simple Mode
             of Facsimile Using Internet Mail", RFC 2305, March 1998.

   [RFC2298] Fajman, R., "An Extensible Message Format for Message
             Disposition Notifications", RFC 2298, March 1998.

   [RFC1123] Braden, R., "Requirements for Internet hosts - Application
             and Support", STD 3, RFC 1123, October 1989.

























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10.  Full Copyright Statement

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   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
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
























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