The checksum in DIASER/UDP/IP is a XOR without STX
draft-petrescu-ipwave-diaser-checksum-01

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IPWAVE Working Group                                         A. Petrescu
Internet-Draft                                                   M. Sarr
Intended status: Standards Track                               CEA, LIST
Expires: November 21, 2019                                  May 20, 2019

           The checksum in DIASER/UDP/IP is a XOR without STX
                draft-petrescu-ipwave-diaser-checksum-01

Abstract

   This document defines the manner in which to calculate the checksum
   for the protocol DIASER.  DIASER is a protocol for communication with
   traffic lights controllers used in France.  DIASER is specified at
   AFNOR.  The specification misses an instruction on how to compute the
   'BCC' checksum ('Byte Character Control').

Status of This Memo

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Petrescu & Sarr         Expires November 21, 2019               [Page 1]
Internet-Draft               DIASER-checksum                    May 2019

Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  DIASER Protocol and IETF Protocols  . . . . . . . . . . . . .   2
   3.  Checksum  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Appendix A.  ChangeLog  . . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  DIASER Protocol and IETF Protocols

   The DIASER protocol does this and that with a Traffic Lights
   controller - it is an Application Layer protocol.  DIASER can be
   transported over UDP and over IP.  The DIASER specification is
   available at a cost from AFNOR, on the World Wide Web.  The DIASER
   specification does not describe the mechanism to compute the checksum
   'BCC' (Byte Control Character).  There exist several verbal (oral)
   versions of this mechanism: to cover or not to cover the STX (Start
   of Text), or the ETX (End of Text).  Studying some implementations of
   a particular controller (Aximum) and packet dumps from independent
   sources, lead to a possibility to reverse engineer the specification
   of the checksum calculation of DIASER.

   The DIASER protocol is an application layer protocol.  Initially it
   was designed to run on serial lines like RS-232.  Later on it was put
   on UDP (User Datagram Protocol).  The UDP protocol is an IETF
   protocol.  Running DIASER over UDP over IP is a great fact; contrary
   to RS-232, it allows to query a Traffic Lights Controller from a
   remote 'Poste de Commande et Control', and further from any other
   point in the Internet; second, it allows to query the controller over
   the future generation of Internet Protocol namely IPv6; thirdly, it
   allows to query the controller from nearby like an autonomous
   shuttle, with lower latency communications, thus supporting higher
   autonomous shuttle speeds; fourthly, it is easy to secure - rely on
   numerous security tools for software (IPsec, VPN) widely available
   and enjoy trust developped by Certificate Authorities and Let's
   Encrypt.
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