Problem Statement and Requirements for Header Protection
draft-ietf-lamps-header-protection-requirements-00

Document Type Active Internet-Draft (lamps WG)
Last updated 2019-07-08
Replaces draft-melnikov-lamps-header-protection
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Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Informational                              B. Hoeneisen
Expires: January 9, 2020                                         Ucom.ch
                                                           July 08, 2019

        Problem Statement and Requirements for Header Protection
           draft-ietf-lamps-header-protection-requirements-00

Abstract

   Privacy and security issues with email header protection in S/MIME
   have been identified for some time.  However, the desire to fix these
   issue has been expressed in the IETF LAMPS Working Group only
   recently.  The existing S/MIME specification is likely to be updated
   regarding header protection.

   Several LAMPS WG participants expressed the opinion that whatever
   mechanism will be chosen, it should not be limited to S/MIME, but
   also applicable to PGP/MIME.

   This document describes the problem statement, generic use cases, and
   requirements.  Additionally it drafts possible solutions to address
   the challenge.  Finally some best practices are collected.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on January 9, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Melnikov & Hoeneisen     Expires January 9, 2020                [Page 1]
Internet-Draft       Header Protection requirements            July 2019

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (https://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     1.2.  Terms . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Interactions  . . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  Protection Levels . . . . . . . . . . . . . . . . . . . .   6
   4.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  General Requirements  . . . . . . . . . . . . . . . . . .   6
       4.1.1.  Sending Side  . . . . . . . . . . . . . . . . . . . .   7
       4.1.2.  Receiving Side  . . . . . . . . . . . . . . . . . . .   7
     4.2.  Additional Requirements for Backward-Compatibility With
           Legacy Clients Unaware of Header Protection . . . . . . .   8
       4.2.1.  Sending side  . . . . . . . . . . . . . . . . . . . .   8
       4.2.2.  Receiving side  . . . . . . . . . . . . . . . . . . .   8
     4.3.  Additional Requirements for Backward-Compatibility with
           Legacy Header Protection Systems (if supported) . . . . .   8
       4.3.1.  Sending Side  . . . . . . . . . . . . . . . . . . . .   9
       4.3.2.  Receiving Side  . . . . . . . . . . . . . . . . . . .   9
   5.  Options to Achieve Header Protection  . . . . . . . . . . . .   9
     5.1.  Option 1: Memory Hole . . . . . . . . . . . . . . . . . .   9
     5.2.  Option 2: Wrapping with message/rfc822 or message/global    9
       5.2.1.  Content-Type Parameter "forwarded"  . . . . . . . . .  10
     5.3.  Option 2.1: Progressive Header Disclosure . . . . . . . .  10
     5.4.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  11
       5.4.1.  Option 1: Memory Hole . . . . . . . . . . . . . . . .  12
       5.4.2.  Option 2: Wrapping with message/rfc822 or
               message/global  . . . . . . . . . . . . . . . . . . .  13
       5.4.3.  Option 2.1 Progressive Header Disclosure  . . . . . .  14
   6.  Sending Side Considerations . . . . . . . . . . . . . . . . .  14
     6.1.  Candidate Header Fields for Header Protection . . . . . .  14
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