Guidance for NSEC3 parameter settings
draft-hardaker-dnsop-nsec3-guidance-02
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Active Internet-Draft (individual)
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Wes Hardaker
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Viktor Dukhovni
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2021-02-19
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Consensus Boilerplate |
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dnsop at IETF-110
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I-D Exists
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Network Working Group W. Hardaker
Internet-Draft USC/ISI
Intended status: Best Current Practice V. Dukhovni
Expires: August 23, 2021 Bloomberg, L.P.
February 19, 2021
Guidance for NSEC3 parameter settings
draft-hardaker-dnsop-nsec3-guidance-02
Abstract
NSEC3 is a DNSSEC mechanism providing proof of non-existence by
promising there are no names that exist between two domainnames
within a zone. Unlike its counterpart NSEC, NSEC3 avoids directly
disclosing the bounding domainname pairs. This document provides
guidance on setting NSEC3 parameters based on recent operational
deployment experience.
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 August 23, 2021.
Copyright Notice
Copyright (c) 2021 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
(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
Hardaker & Dukhovni Expires August 23, 2021 [Page 1]
Internet-Draft title February 2021
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3
2. Recommendation for zone publishers . . . . . . . . . . . . . 3
2.1. Algorithms . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Flags . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3. Iterations . . . . . . . . . . . . . . . . . . . . . . . 3
2.4. Salt . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Best-practice for zone publishers . . . . . . . . . . . . . . 5
4. Recommendation for validating resolvers . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Operational Considerations . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 6
Appendix B. Github Version of this document . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
As with NSEC [RFC4035], NSEC3 [RFC5155] provides proof of non-
existence that consists of signed DNS records establishing the non-
existence of a given name or associated Resource Record Type (RRTYPE)
in a DNSSEC [RFC4035] signed zone. In the case of NSEC3, however,
the names of valid nodes in the zone are obfuscated through (possibly
multiple iterations of) hashing via SHA-1. (currently only SHA-1 is
in use within the Internet).
NSEC3 also provides "opt-out support", allowing for blocks of
unsigned delegations to be covered by a single NSEC3 record. Opt-out
blocks allow large registries to only sign as many NSEC3 records as
there are signed DS or other RRsets in the zone - with opt-out,
unsigned delegations don't require additional NSEC3 records. This
sacrifices the tamper-resistance proof of non-existence offered by
NSEC3 in order to reduce memory and CPU overheads.
NSEC3 records have a number of tunable parameters that are specified
via an NSEC3PARAM record at the zone apex. These parameters are the
Hash Algorithm, processing Flags, the number of hash Iterations and
the Salt. Each of these has security and operational considerations
that impact both zone owners and validating resolvers. This document
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