pretty Easy privacy (pEp): Contact and Channel Authentication through Handshake
draft-marques-pep-handshake-05

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Network Working Group                                         H. Marques
Internet-Draft                                              B. Hoeneisen
Intended status: Standards Track                          pEp Foundation
Expires: January 9, 2021                                   July 08, 2020

 pretty Easy privacy (pEp): Contact and Channel Authentication through
                               Handshake
                     draft-marques-pep-handshake-05

Abstract

   In interpersonal messaging, end-to-end encryption means for public
   key distribution and verification of its authenticity are needed; the
   latter to prevent man-in-the-middle (MITM) attacks.

   This document proposes a new method to easily verify a public key is
   authentic by a Handshake process that allows users to easily
   authenticate their communication channel.  The new method is targeted
   to Opportunistic Security scenarios and is already implemented in
   several applications of pretty Easy privacy (pEp).

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on January 9, 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Terms . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Existing Solutions  . . . . . . . . . . . . . . . . . . .   4
   3.  The pEp Handshake Proposal  . . . . . . . . . . . . . . . . .   5
     3.1.  Verification Process  . . . . . . . . . . . . . . . . . .   6
       3.1.1.  Short, Long and Full Trustword Mapping  . . . . . . .   7
       3.1.2.  Display Modes . . . . . . . . . . . . . . . . . . . .   8
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   5.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Implementation Status . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Introduction  . . . . . . . . . . . . . . . . . . . . . .   9
     7.2.  Current software implementing pEp . . . . . . . . . . . .   9
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Appendix A.  Document Changelog . . . . . . . . . . . . . . . . .  12
   Appendix B.  Open Issues  . . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   In interpersonal messaging end-to-end encryption means for public key
   distribution and verification of its authenticity are needed.

   Examples for key distribution include:

   o  Exchange public keys out-of-band before encrypted communication

   o  Use of centralized public key stores (e.g., OpenPGP Key Servers)

   o  Ship public keys in-band when communicating

   To prevent man-in-the-middle (MITM) attacks, additionally the
   authenticity of a public key needs to be verified.  Methods to
   authenticate public keys of peers include, e.g., to verify digital

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