DNSOP                                                          G. Huston
Internet-Draft                                                  J. Damas
Intended status: Standards Track                                   APNIC
Expires: April 5, 2018                                   October 2, 2017


            A Sentinel for Detecting Trusted Keys in DNSSEC
                  draft-huston-kskroll-sentinel-00.txt

Abstract

   The DNS Security Extensions (DNSSEC) were developed to provide origin
   authentication and integrity protection for DNS data by using digital
   signatures.  These digital signatures can be verified by building a
   chain of trust starting from a trust anchor and proceeding down to a
   particular node in the DNS.  This document specifies a mechanism that
   will allow an end user to establish the trusted key state of the
   resolvers that handle the user's DNS queries.  This allows users to
   discover the trusted key state used by their DNS resolution service.

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
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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
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   This Internet-Draft will expire on April 5, 2018.

Copyright Notice

   Copyright (c) 2017 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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   to this document.  Code Components extracted from this document must



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   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.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Sentinel Mechanism  . . . . . . . . . . . . . . . . . . . . .   3
   3.  Sentinel Processing . . . . . . . . . . . . . . . . . . . . .   3
   4.  Sentinel Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

.  Introduction

   The DNS Security Extensions (DNSSEC) [RFC4033]", [RFC4034] and
   [RFC4035] were developed to provide origin authentication and
   integrity protection for DNS data by using digital signatures.
   DNSSEC uses Key Tags to efficiently match signatures to the keys from
   which they are generated.  The Key Tag is a 16-bit value computed
   from the RDATA portion of a DNSKEY RR using a formula not unlike a
   ones-complement checksum.  RRSIG RRs contain a Key Tag field whose
   value is equal to the Key Tag of the DNSKEY RR that validates the
   signature.

   This document specifies how validating resolvers should respond to
   certain queries so that a user can deduce whether a key has been
   loaded into a resolver's trusted key store.  This mechanism can be
   used to determine whether a certain Root Zone KSK is ready to be used
   as a trusted key within the context of a key roll.

   This new mechanism is OPTIONAL to implement and use, although for
   reasons of supporting broad based measurement techniques, it is
   strongly preferred if configurations of DNSSEC-vbalidating resolvers
   enabled this mechanism by default, allowing for configuration
   directives to disable this mechanism if desired.

1.1.  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.



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.  Sentinel Mechanism

   DNSSEC-Validating resolvers that implement this mechanism MUST be
   performing validation of responses in accordance with the DNSSEC
   response validation specification [RFC4035].

   If the outcome of the DNS response validation process indicates that
   the response is authentic, and if the original query contains exactly
   one label that matches the template ".is-ta-<tag-index>.", then the
   following rule should be applied to the response.  If the resolver
   has placed a Root Zone Key Signing Key with tag index value matching
   the value specified in the query into the local resolver's store of
   trusted keys, then the resolver should return a response indicatating
   that the response contains authenticated data according to section
   5.8 of [RFC6840].  Otherwise, the resolver MUST return RCODE 2
   (server failure).  Note that the <tag-index> is specified in the DNS
   label using hex notation.

   If the outcome of the DNS response validation process indicates that
   the response is authentic, and if the original query contains exactly
   one label that matches the template ".not-ta-<tag-index>.", then the
   following rule should be applied to the response.  If the resolver
   has not placed a Root Zone Key Signing Key with tag index value
   matching the value specified in the query into the local resolver's
   store of trusted keys, then the resolver should return a response
   indicatating that the response contains authenticated data according
   to section 5.8 of [RFC6840].  Otherwise, the resolver MUST return
   RCODE 2 (server failure).  Note that the <tag-index> is specified in
   the DNS label using hex notation.

   If a query contains one instance of both of these query templates
   then the resolver MUST NOT alter the outcome of the DNS response
   validation process.

.  Sentinel Processing

   [Text to be added as to how to pose queries and interpret responses]

.  Sentinel Considerations

   [Text to be added about considerations relating to caching, and
   resolver forwarding partial deployment of the mechanism, as well as
   any other issues that may arise with this mechanism]








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.  Security Considerations

   This document describes a mechanism to allow users to determine the
   trust state of root zone key signing keys in the DNS resolutiojn
   system that they use.

   The mechanism does not require resolvers to set outwise
   unauthenticated responses to be marked as authenticated, and does not
   alter the security properties of DNSSEC with respect to the
   interpretation of the authenticity of responses that are do marked.

   The mechanism does not require any further significant processing of
   DNS responses, and queries of the form described in this document do
   not impose any additional load that could be exploited in an attack
   over the the normal DNSSEC validation processing load.

.  IANA Considerations

   [Note to IANA, to be removed prior to publication: there are no IANA
   considerations stated in this version of the document.]

.  Acknowledgements

   This document has borrowed extensively from RFC8145 for the
   introductory text, and the authors would like to acknowledge and
   thank the authors of that document both for some text excerpts and
   for the more general stimulation of thoughts about monitoring the
   progress of a roll of the Key Signing Key of the Root Zone of the
   DNS.

.  References

8.1.  Normative References

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements",
              RFC 4033, DOI 10.17487/RFC4033, March 2005,
              <https://www.rfc-editor.org/info/rfc4033>.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, DOI 10.17487/RFC4034, March 2005,
              <https://www.rfc-editor.org/info/rfc4034>.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
              <https://www.rfc-editor.org/info/rfc4035>.



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   [RFC6840]  Weiler, S., Ed. and D. Blacka, Ed., "Clarifications and
              Implementation Notes for DNS Security (DNSSEC)", RFC 6840,
              DOI 10.17487/RFC6840, February 2013,
              <https://www.rfc-editor.org/info/rfc6840>.

8.2.  Informative References

   [RFC8145]  Wessels, D., Kumari, W., and P. Hoffman, "Signaling Trust
              Anchor Knowledge in DNS Security Extensions (DNSSEC)",
              RFC 8145, DOI 10.17487/RFC8145, April 2017,
              <https://www.rfc-editor.org/info/rfc8145>.

Authors' Addresses

   Geoff Huston

   Email: gih@apnic.net
   URI:   http://www.apnic.net


   Joao da Silva Damas

   Email: joao@apnic.net
   URI:   http://www.apnic.net



























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