Recursive to Authoritative DNS with Opportunistic Encryption
draft-pp-recursive-authoritative-opportunistic-02

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Author Paul Hoffman 
Last updated 2020-11-19
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Network Working Group                                         P. Hoffman
Internet-Draft                                                     ICANN
Intended status: Standards Track                        19 November 2020
Expires: 23 May 2021

      Recursive to Authoritative DNS with Opportunistic Encryption
             draft-pp-recursive-authoritative-opportunistic-02

Abstract

   This document describes a use case and a method for a DNS recursive
   resolver to use opportunistic encryption when communicating with
   authoritative servers.  A motivating use case for this method is that
   more encryption on the Internet is better, and opportunistic
   encryption is better than no encryption at all.  The method here is
   optional for both the recursive resolver and the authoritative
   server.  Nothing in this method prevents use cases and methods that
   require authenticated encryption.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   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 23 May 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Use Case  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.2.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Method for Opportunistic Encryption . . . . . . . . . . . . .   3
   3.  Transport Caches  . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   A recursive resolver using traditional DNS over port 53 may wish
   instead to use encrypted communication with authoritative servers in
   order to prevent passive snooping of its DNS traffic.  The recursive
   resolver can use opportunistic encryption (defined in [RFC7435] to
   achieve this goal.

   This document describes a use case and a method for recursive
   resolvers to use opportunistic encryption.  The use case is described
   in Section 1.1.  The method uses DNS-over-TLS [RFC7858] with
   authoritative servers in an efficient manner.

1.1.  Use Case

   The use case in this document is recursive resolver operators who are
   happy to use TLS [RFC8446] encryption with authoritative servers if
   doing so doesn't significantly slow down getting answers, and
   authoritative server operators that are happy to use encryption with
   recursive resolvers if it doesn't cost much.

   Both parties understand that using encryption costs something, but
   are willing to absorb the costs for the benefit of more Internet
   traffic being encrypted.  The extra costs (compared to using
   traditional DNS on port 53) include:

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   *  Extra round trips to establish TCP for every session

   *  Extra round trips for TLS establishment

   *  Greater CPU use for TLS establishment

   *  Greater CPU use for encryption after TLS establishment

   *  Greater memory use for holding TLS state

1.2.  Definitions

   The terms "recursive resolver" and "authoritative server" are defined
   in [RFC8499].

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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