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draft-vaudreuil-mime-sig-00.txt
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Network Working Group Gregory M. Vaudreuil
Internet Draft Tigon Corporation
Expires 4/18/94 October 18th, 1993
Application/Signature
<draft-vaudreuil-mime-sig-00.txt>
1.Status of this Memo
This document is an Internet Draft. 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 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 a "work in progress".
2.Abstract
The memo defines a MIME content type for the exchange of sender
contact information and user agent capability information beyond what
is feasable in the RFC822 header. This exchange is generally
accomplished by use of a signature trailer appended to the message.
These signatures commonly contain address, phone, and email
addressing. This document outlines a formalization and extension of
the signature concept to provide a machine readable, internationally
friendly form to exchange this information.
3.Introduction
Mechanisms for the exchange of contact information are lacking in the
general internet. Directory services are not ubiquitous and it is not
clear how to search for a given person even when they are available.
The exchange of business cards provides a mechanism for identifying a
specific person when you meet them. The application/signature body
part provides a similar mechanism, to deliver contact information to a
person you "meet" over electronic mail.
The information to be exchanged between people over electronic mail is
also growing. As Privacy Enhanced Mail grows in popularity, accessory
information such as public keys becomes more essential to exchange
with those who you normally contact. As Internet mail becomes multi-
media, the exchange of information, such as a small portrait or short
audio greeting become as useful as the RFC822 text name for
identifying the sender.
As the number of content-types, languages, and character sets
increase, it becomes more essential to identify the capabilities of
the destination mail agents without having to wait for error reports
and letters of complaint. The Application/Signature body part
Internet Draft Application/Signature Expires 4/10/93
provides a mechanism for sending a list of MIME content-types, the
character sets supported, and the languages spoken by the mailbox
owner.
By saving and caching the information provided in the
application/signature body part, a database of destinations frequently
contacted can be populated and updated. This database can be used for
providing basic, local alias directory services and can be used by
mailers to notify the sender before sending the message if it is
supported by the receiver.
Automated update of the database requires loosely standardized
attribute/value pair definitions. These elements are based on the
MIME content-type/sub-type registry. Each attribute registration
includes all information needed to unambiguously identify the content-
type, parameters such as character set, and transport encoding.
This specification does not explicitly include a universal database
key value. X.500 distinguished names and email addresses may provide
a suitable mechanism for correlating updates and providing lookup
functions.
4.Definition of the Application/Signature Body Part
Mime type name: Application
Mime Sub-Type name: Signature
Required Parameters: None
Optional Parameters: None
Encoding Considerations: 7 bit is always sufficient.
The application/signature body part should be included as the last
body part in a top-level Multipart/Mixed construct.
The Application/Signature body part is a sequence of attribute/value
pairs formatted according to the rules of RFC 822 header lines. As in
RFC822 headers, lines may be wrapped and continued on subsequent lines
by indenting with linear white space. Comments are optional and are
not considered part of the value if included.
All lines must be in 7bit US ASCII format. Non US ASCII textual data
can be represented using the RFC 1522 encoded word. Non-text data
must be encoded using base-64 or quoted printable, with the specific
encoding specified in the attribute definition.
The list of allowable attributes is maintained by the IANA. Except
for Text/Plain, registered values must correspond to exactly one
previously registered MIME content-subtype and must include constant
values for all necessary parameters and specify the transport encoding
if needed. Use of X- for experimental and bi-laterally defined
(Private) values is permitted.
The attribute "Capabilities" is provided to identify the MIME content-
types supported by the destination. The list of attributes should
Vaudreuil [Page 2]
Internet Draft Application/Signature Expires 4/10/93
include any IANA registered content-type. To reduce the amount of
data transferred, the list of capabilities should not include the
basic MIME constructor types. These types are Message/RFC822,
Message/Partial, Multipart/Mixed, Multipart/Parallel,
Multipart/Alternative, and Application/Octet-Stream. Text/Plain if
supported should be explicitly identified as some mixed media agents
may not support text output.
The attribute "Charsets" is provided to identify the character sets
accepted for use in Text/* bodyparts. The list of character sets can
include any IANA registered character set. US-ASCII does not need to
be identified as it the default character set. The character sets
should be listed in the order of preference.
The attribute "Languages" is provided to communicate the languages
understood by the mailbox owner. As communication becomes increasing
global, a list of languages will allow the sender to choose an
appropriate language without guessing. The set of language identifier
can include any registered in XXXXX(need reference). The languages
should be listed in the order of preference.
Vaudreuil [Page 3]
Internet Draft Application/Signature Expires 4/10/93
Initially Defined Application/Signature Values . 5
Attribute Content Type Description
Encoding
Email Text/Plain A fully qualified domain name style
7bit address.
Name Text/Plain The name of the mailbox owner. Latin
7bit derived names must be in the Last, First,
Middle initial format for ease of parsing.
Telephone Text/Plain The international version of the telephone
7bit number. Multiple telephone numbers can be
differentiated by use of an RFC 822
comment.
Fax Text/Plain The international verison of the
7bit fascimilie number.
Address Text/Plain The postal address, each line separated
7bit with a slash "/".
Portrait Image/Gif A small bitmap portrait. This may be used
Base-64 for visual message waiting identification.
SpokenName Audio/ADPCM A short phrase containing the name in the
Base-64 voice of the mailbox owner.
Capabilities Text/Plain A coma separated list of the MIME content-
7bit types the mailbox owner is willing to
accept. Message/RFC822, Message/Partial,
Multipart/Mixed, Multipart/Parallel, and
Multipart/Alternative are required and
need not be listed.
Text Text/Plain Free form text for comments, quotes, and
7bit ASCII art.
Vaudreuil [Page 4]
Internet Draft Application/Signature Expires 4/10/93
Charsets Text/Plain A coma separated prioritized list of the
MIME content-types supported by the user
agent.
Languages Text/Plain A coma separated prioritized list of the
languages understood by the mailbox owner.
PEM_Cert Text/Plain The PEM certificate of the mailbox owner
7bit as specified in RFC 1421.
Distname Text/Plain The X.500 distinguished name of the
7bit mailbox owner.
Vaudreuil [Page ] 5
Internet Draft Application/Signature Expires 4/10/93
6.Example Application/Signature Body Part
Content-Type: Application/Signature
Name: Gregory M. Vaudreuil
Email: GVaudre@cnri.reston.va.us
Telephone: +1 214 555 2121 (Work)
Fax: +1 214 555 3232
Address: 17080 Dallas Parkway/Suite 100/Dallas Texas, 75248
Portrait: R0lGODdhEAAQAIAAAAAAAP///ywAAAAAEAAQAAACK4wNqceR7UCT8FB
n2aUc47550nZ5iFZWVqpG2bS+WhbK3frYrYmwOaRYMAoAOw==
Capabilities: Text/Plain, Image/GIF, Image/Postscript, Audio/Basic
PEM-Cert: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7.Security Consideration
The information in the application/signature cannot be considered any
more authoritative than the "from" line of the RFC 822 header.
Authentication of the content is left to mechanisms specified in the
Privacy Enhanced Mail extension to RFC 822.
8.Author's Address
Gregory M. Vaudreuil
The Tigon Corporation
17080 Dallas Parkway
Dallas, TX 75248-1905
214-733-2722
Gvaudre@cnri.reston.va.us
Vaudreuil [Page 6]