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