Padding Policy for EDNS(0)
draft-ietf-dprive-padding-policy-06

Document Type Active Internet-Draft (dprive WG)
Last updated 2018-08-01 (latest revision 2018-07-19)
Replaces draft-mayrhofer-dprive-padding-profile
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Intended RFC status Experimental
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Responsible AD Terry Manderson
Send notices to Brian Haberman <brian@innovationslab.net>, dns-privacy@ietf.org
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Network Working Group                                       A. Mayrhofer
Internet-Draft                                               nic.at GmbH
Intended status: Experimental                              July 19, 2018
Expires: January 20, 2019

                       Padding Policy for EDNS(0)
                  draft-ietf-dprive-padding-policy-06

Abstract

   RFC 7830 specifies the EDNS(0) 'Padding' option, but does not specify
   the actual padding length for specific applications.  This memo lists
   the possible options ("Padding Policies"), discusses implications of
   each of these options, and provides a recommended (experimental)
   option.

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
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   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 20, 2019.

Copyright Notice

   Copyright (c) 2018 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
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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   described in the Simplified BSD License.

Mayrhofer               Expires January 20, 2019                [Page 1]
Internet-Draft      draft-ietf-dprive-padding-policy           July 2018

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  General Guidance  . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Padding Strategies  . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Block Length Padding - Recommended Strategy . . . . . . .   3
     4.2.  Other Strategies  . . . . . . . . . . . . . . . . . . . .   5
       4.2.1.  Maximal Length Padding  . . . . . . . . . . . . . . .   5
       4.2.2.  Random Length Padding . . . . . . . . . . . . . . . .   5
       4.2.3.  Random Block Length Padding . . . . . . . . . . . . .   6
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  Changes . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  draft-ietf-dprive-padding-policy-06 . . . . . . . . . . .   7
     8.2.  draft-ietf-dprive-padding-policy-05 . . . . . . . . . . .   7
     8.3.  draft-ietf-dprive-padding-policy-04 . . . . . . . . . . .   8
     8.4.  draft-ietf-dprive-padding-policy-03 . . . . . . . . . . .   8
     8.5.  draft-ietf-dprive-padding-policy-02 . . . . . . . . . . .   8
     8.6.  draft-ietf-dprive-padding-policy-01 . . . . . . . . . . .   8
     8.7.  draft-ietf-dprive-padding-policy-00 . . . . . . . . . . .   8
     8.8.  draft-mayrhofer-dprive-padding-profiles-00  . . . . . . .   8
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Appendix A.  Non-sensible Padding Policies  . . . . . . . . . . .   9
     A.1.  No Padding  . . . . . . . . . . . . . . . . . . . . . . .   9
     A.2.  Fixed Length Padding  . . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   [RFC7830] specifies the Extensions Mechanisms for DNS (EDNS(0))
   "Padding" option, which allows DNS clients and servers to
   artificially increase the size of a DNS message by a variable number
   of bytes, hampering size-based correlation of encrypted DNS messages.

   However, RFC 7830 deliberately does not specify the actual length of
   padding to be used.  This memo discusses options regarding the actual
   size of padding, lists advantages and disadvantages of each of these
   "Padding Strategies", and provides a recommended (experimental)
   strategy.

   Padding DNS messages is useful only when transport is encrypted,
   using protocols such as DNS over Transport Layer Security [RFC7858],
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