Padding Policy for EDNS(0)
draft-ietf-dprive-padding-policy-00

Document Type Active Internet-Draft (dprive WG)
Last updated 2017-01-05 (latest revision 2016-12-05)
Replaces draft-mayrhofer-dprive-padding-profile
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Network Working Group                                       A. Mayrhofer
Internet-Draft                                               nic.at GmbH
Intended status: Standards Track                        December 5, 2016
Expires: June 8, 2017

                       Padding Policy for EDNS(0)
                  draft-ietf-dprive-padding-policy-00

Abstract

   RFC 7830 specifies the EDNS0 'Padding' option, but does not specify
   the amount of padding to be used in specific applications.  This memo
   lists the possible options ("Padding Policies"), discusses the
   implications of each of these options, and provides implementation
   guidance.

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
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   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 June 8, 2017.

Copyright Notice

   Copyright (c) 2016 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Mayrhofer                 Expires June 8, 2017                  [Page 1]
Internet-Draft      draft-ietf-dprive-padding-policy       December 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  General Guidance  . . . . . . . . . . . . . . . . . . . . . .   2
   4.  Padding Strategies  . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  No Padding  . . . . . . . . . . . . . . . . . . . . . . .   3
     4.2.  Fixed Length Padding  . . . . . . . . . . . . . . . . . .   3
     4.3.  Block Length Padding  . . . . . . . . . . . . . . . . . .   4
     4.4.  Random Length Padding . . . . . . . . . . . . . . . . . .   4
     4.5.  Random Block Length Padding . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Changes . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  draft-ietf-dprive-padding-policy-00 . . . . . . . . . . .   6
     7.2.  draft-mayrhofer-dprive-padding-profiles-00  . . . . . . .   6
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   RFC 7830 [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 7803 deliberately does not specify the actual amount of
   padding to be used.  This memo discusses options regarding the actual
   size of padding, and lists advantages and disadvantages of each of
   these "Padding Strategies".

2.  Terminology

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

3.  General Guidance

   Padding messages does not have any semantic impact on the DNS
   protocol.  However, the amount of (possible) padding does depend on
   the circumstances under which a DNS message is created, specifically
   the maximum message length as dictated by protocol negotiations.
   Therefore, in order to not impact the possibility to add other EDNS
   options, "Padding" MUST be the last ENDS option applied before a DNS
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