pretty Easy privacy (pEp): Key Synchronization Protocol (KeySync)
draft-pep-keysync-00

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Last updated 2019-11-04
Replaces draft-hoeneisen-pep-keysync
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Network Working Group                                            V. Birk
Internet-Draft                                              B. Hoeneisen
Intended status: Standards Track                              K. Bristol
Expires: May 7, 2020                                      pEp Foundation
                                                       November 04, 2019

   pretty Easy privacy (pEp): Key Synchronization Protocol (KeySync)
                          draft-pep-keysync-00

Abstract

   This document describes the pEp KeySync protocol, which is designed
   to perform secure peer-to-peer synchronization of private keys across
   devices belonging to the same user.

   Modern users of messaging systems typically have multiple devices for
   communicating, and attempting to use encryption on all of these
   devices often leads to situations where messages cannot be decrypted
   on a given device due to missing private key data.  Current
   approaches to resolve key synchronicity issues are cumbersome and
   potentially unsecure.  The pEp KeySync protocol is designed to
   facilitate this personal key synchronization in a user-friendly
   manner.

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 May 7, 2020.

Copyright Notice

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

Birk, et al.               Expires May 7, 2020                  [Page 1]
Internet-Draft      pretty Easy privacy (pEp) KeySync      November 2019

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Terms . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.3.  Problem Statement . . . . . . . . . . . . . . . . . . . .   5
     1.4.  Main Challenge  . . . . . . . . . . . . . . . . . . . . .   5
     1.5.  Approach  . . . . . . . . . . . . . . . . . . . . . . . .   5
   2.  General Description . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Use Cases for pEp KeySync . . . . . . . . . . . . . . . .   6
       2.1.1.  Form Device Group . . . . . . . . . . . . . . . . . .   6
       2.1.2.  Add New Device to Existing Device Group . . . . . . .   7
       2.1.3.  Exchange Private Keys . . . . . . . . . . . . . . . .   7
       2.1.4.  Leave Device Group  . . . . . . . . . . . . . . . . .   7
       2.1.5.  Remove other Device from Device Group . . . . . . . .   8
     2.2.  Interaction Diagrams  . . . . . . . . . . . . . . . . . .   8
       2.2.1.  Form Device Group . . . . . . . . . . . . . . . . . .   9
       2.2.2.  Add New Device to Existing Device Group . . . . . . .  17
       2.2.3.  Exchange Private Keys . . . . . . . . . . . . . . . .  24
       2.2.4.  Leave Device Group  . . . . . . . . . . . . . . . . .  24
       2.2.5.  Remove other Device from Device Group . . . . . . . .  24
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .  24
   4.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  24
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  24
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  24
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  25
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  25
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  25
   Appendix A.  Reference Implementation . . . . . . . . . . . . . .  26
     A.1.  Full Finite-State Machine Diagram . . . . . . . . . . . .  26
       A.1.1.  States  . . . . . . . . . . . . . . . . . . . . . . .  26
       A.1.2.  Actions . . . . . . . . . . . . . . . . . . . . . . .  35
       A.1.3.  Transitions . . . . . . . . . . . . . . . . . . . . .  39
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