Network Time Protocol MAC/Last Extension Fields
draft-stenn-ntp-mac-last-ef-00

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Internet Engineering Task Force                                 H. Stenn
Internet-Draft                                                  D. Mayer
Intended status: Standards Track                 Network Time Foundation
Expires: May 2, 2017                                    October 29, 2016

            Network Time Protocol MAC/Last Extension Fields
                     draft-stenn-ntp-mac-last-ef-00

Abstract

   NTPv4 is defined by RFC 5905 [RFC5905], and it and earlier versions
   of the NTP Protocol have supported symmetric private key Message
   Authentication Code (MAC) authentication.  MACs were first described
   in Appendix C of RFC 1305 [RFC1305] and are further described in RFC
   5905 [RFC5905].  As the number of Extension Fields grows there is an
   increasing chance of a parsing ambiguity when deciding if the "next"
   set of data is an Extension Field or a legacy MAC.  This proposal
   defines two new Extension Fields to avoid this ambiguity.  One is
   used to signifiy that it is the last Extension Field in the packet.
   If present, any subsequent data MUST be considered to be a legacy
   MAC.  The other allows one or more MACs to be encapsulated in an
   Extension Field.  If all parties in an association support MAC-EF,
   the use of a legacy MAC may be avoided.

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 May 2, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Stenn & Mayer              Expires May 2, 2017                  [Page 1]
Internet-Draft        NTP MAC/Last Extension Fields         October 2016

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  The Last Extension Field Extension Field  . . . . . . . . . .   3
   3.  MAC Extension Field . . . . . . . . . . . . . . . . . . . . .   4
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   NTPv4 is defined by RFC 5905 [RFC5905], and it and earlier versions
   of the NTP Protocol have supported symmetric private key Message
   Authentication Code (MAC) authentication.  MACs were first described
   in Appendix C of RFC 1305 [RFC1305] and are further described in RFC
   5905 [RFC5905].  As the number of Extension Fields grows there is an
   increasing chance of a parsing ambiguity when deciding if the "next"
   set of data is an Extension Field or a legacy MAC.  This proposal
   defines two new Extension Fields to avoid this ambiguity.  One is
   used to signifiy that it is the last Extension Field in the packet.
   If present, any subsequent data MUST be considered to be a legacy
   MAC.  The other allows one or more MACs to be encapsulated in an
   Extension Field.  If all parties in an association support MAC-EF,
   the use of a legacy MAC may be avoided.

1.1.  Requirements Language

   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].
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