draft-ietf-dnsop-dnssec-bootstrapping-06.txt

DNSOP Working Group                                         P. Thomassen
Internet-Draft                         deSEC, Secure Systems Engineering
Updates: 7344, 8078 (if approved)                              N. Wisiol
Intended status: Standards Track    deSEC, Technische Universität Berlin
Expires: 4 April 2024                                     2 October 2023


  Automatic DNSSEC Bootstrapping using Authenticated Signals from the
                            Zone's Operator
                draft-ietf-dnsop-dnssec-bootstrapping-06

Abstract

   This document introduces an in-band method for DNS operators to
   publish arbitrary information about the zones they are authoritative
   for, in an authenticated fashion and on a per-zone basis.  The
   mechanism allows managed DNS operators to securely announce DNSSEC
   key parameters for zones under their management, including for zones
   that are not currently securely delegated.

   Whenever DS records are absent for a zone's delegation, this signal
   enables the parent's registry or registrar to cryptographically
   validate the CDS/CDNSKEY records found at the child's apex.  The
   parent can then provision DS records for the delegation without
   resorting to out-of-band validation or weaker types of cross-checks
   such as "Accept after Delay".

   This document deprecates the DS enrollment methods described in
   Section 3 of RFC 8078 in favor of Section 4 of this document, and
   also updates RFC 7344.

   [ Ed note: This document is being collaborated on at
   https://github.com/desec-io/draft-ietf-dnsop-dnssec-bootstrapping/
   (https://github.com/desec-io/draft-ietf-dnsop-dnssec-bootstrapping/).
   The authors gratefully accept pull requests. ]

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/.






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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
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   This Internet-Draft will expire on 4 April 2024.

Copyright Notice

   Copyright (c) 2023 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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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Requirements Notation . . . . . . . . . . . . . . . . . .   5
   2.  Updates to RFCs . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Signaling . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Chain of Trust  . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  Signaling Names . . . . . . . . . . . . . . . . . . . . .   6
   4.  Bootstrapping a DNSSEC Delegation . . . . . . . . . . . . . .   6
     4.1.  Signaling Consent to Act as the Child's Signer  . . . . .   6
       4.1.1.  Example . . . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Validating CDS/CDNSKEY Records for DNSSEC
           Bootstrapping . . . . . . . . . . . . . . . . . . . . . .   7
       4.2.1.  Example . . . . . . . . . . . . . . . . . . . . . . .   8
     4.3.  Triggers  . . . . . . . . . . . . . . . . . . . . . . . .   9
     4.4.  Limitations . . . . . . . . . . . . . . . . . . . . . . .  10
   5.  Operational Recommendations . . . . . . . . . . . . . . . . .  10
     5.1.  Child DNS Operator  . . . . . . . . . . . . . . . . . . .  10
     5.2.  Parental Agent  . . . . . . . . . . . . . . . . . . . . .  10
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   8.  Implementation Status . . . . . . . . . . . . . . . . . . . .  11
     8.1.  Child DNS Operator-side . . . . . . . . . . . . . . . . .  12
     8.2.  Parental Agent-side . . . . . . . . . . . . . . . . . . .  12
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   10. Normative References  . . . . . . . . . . . . . . . . . . . .  13



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   11. Informative References  . . . . . . . . . . . . . . . . . . .  14
   Appendix A.  Change History (to be removed before publication)  .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   Securing a DNS delegation for the first time requires that the
   Child's DNSSEC parameters be conveyed to the Parent through some
   trusted channel.  While the communication conceptually has to occur
   between the Parent registry and the DNSSEC key holder, what exactly
   that means and how the communication is coordinated traditionally
   depends on the relationship the Child has with the Parent.

   A typical situation is that the key is held by the Child DNS
   Operator; the communication thus often involes this entity.  In
   addition, depending on the circumstances, it may also involve the
   Registrar, possibly via the Registrant (for details, see [RFC7344],
   Appendix A).

   As observed in [RFC7344], these dependencies often result in a manual
   process that is susceptible to mistakes and/or errors.  In addition,
   due to the annoyance factor of the process, involved parties may
   avoid the process of getting a DS record set published in the first
   place.

   To alleviate these problems, automated provisioning of DS records has
   been specified in ([RFC8078]).  It is based on the Parental Agent
   (registry or registrar) fetching DNSSEC key parameters from the CDS
   and CDNSKEY records ([RFC7344]) located at the Child zone's apex, and
   validating them somehow.  This validation can be done using the
   Child's existing DNSSEC chain of trust if the objective is to update
   an existing DS record set (such as during key rollover).  However,
   when bootstrapping a DNSSEC delegation, the Child zone has no
   existing DNSSEC validation path, and other means to ensure the CDS/
   CDNSKEY records' legitimacy must be found.

   For lack of a comprehensive DNS-innate solution, either out-of-band
   methods have been used so far to complete the chain of trust, or
   cryptographic validation has been entirely dispensed with, in
   exchange for weaker types of cross-checks such as "Accept after
   Delay" ([RFC8078] Section 3.3).  [RFC8078] does not define an in-band
   validation method for enabling DNSSEC.

   This document aims to close this gap by introducing an in-band method
   for DNS Operators to publish arbitrary information about the zones
   they are authoritative for, in an authenticated manner and on a per-
   zone basis.  The mechanism allows managed DNS Operators to securely
   announce DNSSEC key parameters for zones under their management.  The



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   Parent can then use this signal to cryptographically validate the
   CDS/CDNSKEY records found at an insecure Child zone's apex, and upon
   success secure the delegation.

   While applicable to the vast majority of domains, the protocol does
   not support certain edge cases, such as excessively long Child zone
   names, or DNSSEC bootstrapping for domains with in-bailick
   nameservers only (see Section 4.4).

   DNSSEC bootstrapping is just one application of the generic signaling
   mechanism specified in this document.  Other applications might arise
   in the future, such as publication of API endpoints for third-party
   interaction with the DNS Operator or of other operational metadata
   which the DNS Operator likes to publish.

   Readers are expected to be familiar with DNSSEC, including [RFC4033],
   [RFC4034], [RFC4035], [RFC6781], [RFC7344], and [RFC8078].

1.1.  Terminology

   This section defines the terminology used in this document.

   CDS/CDNSKEY  This notation refers to CDS and/or CDNSKEY, i.e., one or
      both.

   Child  see [RFC8499] Section 7

   Child DNS Operator  The entity that maintains and publishes the zone
      information for the Child DNS.

   Parent  see [RFC8499] Section 7

   Parental Agent  The entity that has the authority to insert DS
      records into the Parent zone on behalf of the Child.  (It could be
      the registry, registrar, a reseller, or some other authorized
      entity.)

   Signaling Domain  A hostname from the Child's NS record set, prefixed
      with the label _signal.  There are as many Signaling Domains as
      there are distinct NS targets.

   Signaling Name  The labels that are prefixed to a Signaling Domain in
      order to identify a Signaling Type and a Child zone's name (see
      Section 3.2).

   Signaling Record  A DNS record located at a Signaling Name under a
      Signaling Domain.  Signaling Records are used by the Child DNS
      Operator to publish information about the Child.



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   Signaling Type  A signal type identifier, such as _dsboot for DNSSEC
      bootstrapping.

   Signaling Zone  The zone which is authoritative for a given Signaling
      Record.

1.2.  Requirements Notation

   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 BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Updates to RFCs

   The DS enrollment methods described in Section 3 of [RFC8078] are
   deprecated and SHOULD NOT be used.  Child DNS Operators and Parental
   Agents who wish to use CDS/CDNSKEY records for initial DS enrollment
   SHOULD instead support the authentication protocol described in
   Section 4 of this document.

   In order to facilitate publication of signaling records for the
   purpose of DNSSEC bootstrapping (see Section 4.1), the first bullet
   ("Location") of [RFC7344] Section 4.1 is removed.

3.  Signaling

   This section describes the general mechanism by which a Child DNS
   Operator can publish an authenticated signal about a Child zone.
   Parental Agents (or any other party) can then discover and process
   the signal.  Authenticity is ensured through standard DNSSEC
   validation.

3.1.  Chain of Trust

   If a Child DNS Operator implements the protocol, each Signaling Zone
   MUST be signed and be validatable by the Parental Agent (i.e. have a
   valid DNSSEC chain of trust).  This is typically achieved by securely
   delegating each Signaling Zone.

   For example, when publishing a signal that relates to a Child zone
   with NS records ns1.example.net and ns2.example.org, the Child DNS
   Operator needs to ensure that the Parental Agent has a valid DNSSEC
   chain of trust for the zone(s) that are authoritative for the
   Signaling Domains _signal.ns1.example.net and
   _signal.ns2.example.org.




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3.2.  Signaling Names

   To publish a piece of information about the Child zone in an
   authenticated fashion, the Child DNS Operator MUST publish one or
   more Signaling Records at a Signaling Name under each Signaling
   Domain.

   Signaling Records MUST be accompanied by RRSIG records created with
   the corresponding Signaling Zone's key(s).  The type and contents of
   these Signaling Records depend on the type of signal.

   The Signaling Name identifies the Child and the Signaling Type.  It
   is identical to the Child name (with the final root label removed),
   prefixed with a label containing the Signaling Type.

4.  Bootstrapping a DNSSEC Delegation

   When the Child zone's CDS/CDNSKEY RRsets are used for setting up
   initial trust, they need to be authenticated.  This is achieved by
   co-publishing the Child's CDS/CDNSKEY records as an authenticated
   signal as described in Section 3.  The Parent can discover and
   validate it, thus transferring trust from the Child DNS Operator
   nameservers' chain of trust to the Child zone.

   This protocol is not intended for updating an existing DS RRset.  For
   this purpose, the Parental Agent can validate the Child's CDS/CDNSKEY
   records directly, using the chain of trust established by the
   existing DS RRset ([RFC7344] Section 4).

4.1.  Signaling Consent to Act as the Child's Signer

   To confirm its willingness to act as the Child's delegated signer and
   authenticate the Child's CDS/CDNSKEY RRsets, the Child DNS Operator
   MUST co-publish them at the corresponding Signaling Name under each
   out-of-bailiwick Signaling Domain (Section 3.2).  For simplicity, the
   Child DNS Operator MAY also co-publish the Child's CDS/CDNSKEY RRsets
   under Signaling Domains that are in bailiwick, although those
   Signaling Domains are not used for validation (Section 4.2).

   Unlike the CDS/CDNSKEY records at the Child's apex, Signaling Records
   MUST be signed with the corresponding Signaling Zone's key(s).  Their
   contents MUST be identical to the corresponding records published at
   the Child's apex.








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   Existing use of CDS/CDNSKEY records was specified at the Child apex
   only ([RFC7344], Section 4.1).  This protocol extends the use of
   these record types to non-apex owner names for the purpose of DNSSEC
   bootstrapping.  To exclude the possibility of semantic collision,
   there MUST NOT be a zone cut at a Signaling Name.

4.1.1.  Example

   For the purposes of bootstrapping the Child zone example.co.uk with
   NS records ns1.example.net, ns2.example.org, and ns3.example.co.uk,
   the required Signaling Domains are _signal.ns1.example.net and
   _signal.ns2.example.org.

   In the zones containing these domains, the Child DNS Operator
   authenticates the CDS/CDNSKEY records found at the Child's apex by
   co-publishing them at the names:

   _dsboot.example.co.uk._signal.ns1.example.net
   _dsboot.example.co.uk._signal.ns2.example.org

   The records are accompanied by RRSIG records created using the key(s)
   of the respective Signaling Zone.

   Publication of Signaling Records under the in-bailiwick domain
   _signal.ns3.example.co.uk is not required.

4.2.  Validating CDS/CDNSKEY Records for DNSSEC Bootstrapping

   To validate a Child's CDS/CDNSKEY RRset for DNSSEC bootstrapping, the
   Parental Agent, knowing both the Child zone name and its NS
   hostnames, MUST execute the following steps:

   1.  verify that the Child is not currently securely delegated and
       that at least one of its nameservers is out of bailiwick;

   2.  query the CDS/CDNSKEY records at the Child zone apex directly
       from each of the authoritative servers as determined by the
       delegation's NS record set (without caching);

   3.  query the CDS/CDNSKEY records located at the Signaling Name under
       each out-of-bailiwick Signaling Domain using a trusted DNS
       resolver and enforce DNSSEC validation;

   4.  check (separately by record type) that all record sets retrieved
       in Steps 2 and 3 have equal contents;






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   If the above steps succeed without error, the CDS/CDNSKEY records are
   successfully validated, and the Parental Agent can proceed with the
   publication of the DS record set under the precautions described in
   [RFC8078], Section 5.

   If, however, an error condition occurs, in particular:

   *  in Step 1: the Child is already securely delegated or has in-
      bailiwick nameservers only;

   *  in Step 2: any failure during the retrieval of the CDS/CDNSKEY
      records located at the Child apex from any of the authoritative
      nameservers;

   *  in Step 3: any failure to retrieve the CDS/CDNSKEY RRsets located
      at the Signaling Name under any Signaling Domain, including
      failure of DNSSEC validation, or unauthenticated data (AD bit not
      set);

   *  in Step 4: inconsistent responses (for at least one of the types),
      including a record set that is empty in one of Steps 2 or 3, but
      non-empty in the other;

   the Parental Agent MUST abort the procedure.

4.2.1.  Example

   To verify the CDS/CDNSKEY records for the Child example.co.uk, the
   Parental Agent (assuming that the Child delegation's NS records are
   ns1.example.net, ns2.example.org, and ns3.example.co.uk)

   1.  checks that the Child domain is not yet securely delegated;

   2.  queries CDS/CDNSKEY records for example.co.uk directly from
       ns1.example.net, ns2.example.org, and ns3.example.co.uk (without
       caching);

   3.  queries and validates the CDS/CDNSKEY records located at (see
       Section 3.2; ns3.example.co.uk is ignored because it is in
       bailiwick)

   _dsboot.example.co.uk._signal.ns1.example.net
   _dsboot.example.co.uk._signal.ns2.example.org

   4.  checks that the CDS/CDNSKEY record sets retrieved in Steps 2 and
       3 agree across responses.





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   If all these steps succeed, the Parental Agent can proceed to publish
   a DS record set as indicated by the validated CDS/CDNSKEY records.

   The Parental Agent does not use in-bailiwick Signaling Names during
   validation because they cannot have a pre-established chain of trust
   at bootstrapping time, so are not useful for bootstrapping.
   Consequently, if all NS hostnames are in bailiwick, validation cannot
   be completed, and DS records are not published.

4.3.  Triggers

   Parental Agents SHOULD trigger the procedure described in Section 4.2
   once one of the following conditions is fulfilled:

   *  The Parental Agent receives a new or updated NS record set for a
      Child;

   *  The Parental Agent encounters a Signaling Record during a
      proactive, opportunistic scan (e.g. daily queries of Signaling
      Records for some or all of its delegations);

   *  The Parental Agent encounters a Signaling Record during an NSEC
      walk or when parsing a Signaling Zone (e.g. when made available
      via AXFR by the Child DNS Operator);

   *  Any other condition as deemed appropriate by local policy.

   Most types of discovery (such as daily scans of delegations) are
   based directly on the delegation's NS record set.  In this case,
   these NS names can be used as is by the bootstrapping algorithm
   (Section 4.2) for querying Signaling Records.

   Some discovery methods, however, do not imply reliable knowledge of
   the Child's NS record set.  For example, when discovering Signaling
   Names by performing an NSEC walk or zone transfer of a Signaling
   Zone, the Parental Agent MUST NOT assume that the nameserver(s) under
   whose Signaling Domain(s) a Signaling Name appears is in fact
   authoritative for the corresponding Child.

   In this case (and in other cases alike where some list of
   "bootstrappable domains" is retrieved from elsewhere), the Parental
   Agent MUST ascertain that the Child's delegation actually contains
   the nameserver hostname seen during discovery, and ensure that
   Signaling Record queries are only made against the proper set of
   nameservers as listed in the Child's delegation from the Parent.






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4.4.  Limitations

   As a consequence of Step 3 in Section 4.2, DS bootstrapping does not
   work for fully in-bailiwick delegations, as no pre-existing chain of
   trust to the Child domain is available during bootstrapping.  (As a
   workaround, one can add an out-of-bailiwick nameserver to the initial
   NS record set and remove it once bootstrapping is completed.
   Automation for this is available via CSYNC records, see [RFC7477].)

   The protocol is further restricted by the fact that the fully
   qualified Signaling Names fit within the general limits that apply to
   DNS names (such as their length and label count).

5.  Operational Recommendations

5.1.  Child DNS Operator

   CDS/CDNSKEY records and corresponding signaling records MUST NOT be
   published without the zone owner's consent.  Likewise, the Child DNS
   Operator MUST enable the zone owner to signal the desire to turn off
   DNSSEC by publication of the special-value CDS/CDNSKEY RRset
   specified in [RFC8078] Section 4.  To facilitate transitions between
   DNS operators, Child DNS Operators SHOULD support the multi-signer
   protocols described in [RFC8901].

   Signaling Domains SHOULD be delegated as zones of their own, so that
   the Signaling Zone's apex coincides with the Signaling Domain (such
   as _signal.ns1.example.net).  While it is permissible for the
   Signaling Domain to be contained in a Signaling Zone of fewer labels
   (such as example.net), a zone cut ensures that bootstrapping
   activities do not require modifications of the zone containing the
   nameserver hostname.

   To keep the size of the Signaling Zones minimal and bulk processing
   efficient (such as via zone transfers), Child DNS Operators SHOULD
   remove Signaling Records which are found to have been acted upon.

5.2.  Parental Agent

   It is RECOMMENDED to perform queries within Signaling Domains
   (Section 4.2) with an (initially) cold resolver cache or to limit the
   TTL of cached records to the interval between scans, as to retrieve
   the most current information regardless of TTL.  (When a batch job is
   used to attempt bootstrapping for a large number of delegations, the
   cache does not need to get cleared in between queries pertaining to
   different Children.)





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6.  Security Considerations

   The DNSSEC bootstrapping method introduced in this document is based
   on the (now deprecated) approaches described in [RFC8078] Section 3,
   but adds authentication to the CDS/CDNSKEY concept.  Its security
   level is therefore strictly higher than that of existing approaches
   described in that document (e.g.  "Accept after Delay").  Apart from
   this general improvement, the same Security Considerations apply as
   in [RFC8078].

   The level of rigor in Section 4.2 is needed to prevent publication of
   a half-baked DS RRset (authorized only under a subset of NS
   hostnames).  This ensures, for example, that an operator in a multi-
   homed setup cannot enable DNSSEC unless all other operators agree.

   Because the parents of a Signaling Domain (such as the corresponding
   TLD registry) are in control of its chain of trust, they are also
   able to undermine the signal's authenticity.  To mitigate this risk,
   it is RECOMMENDED to increase the effort required to collude for
   taking control of all Signaling Domains, by diversifying the path
   from the root to each nameserver.  This is best achieved by using
   different and independently operated TLDs for each one.  (TLD-
   independent NS hostnames are advisable anyways in DNS operations, in
   order to prevent the TLD from becoming a single point of failure.)
   Furthermore, as the Child DNS Operator has authoritative knowledge of
   the Child's CDS/CDNSKEY records, it can readily detect fraudulent
   provisioning of DS records.

7.  IANA Considerations

   Per [RFC8552], IANA is requested to add the following entries to the
   "Underscored and Globally Scoped DNS Node Names" registry:

   +---------+------------+-----------------------------------------+
   | RR Type | _NODE NAME | Reference                               |
   +---------+------------+-----------------------------------------+
   | CDS     | _signal    | [draft-ietf-dnsop-dnssec-bootstrapping] |
   | CDNSKEY | _signal    | [draft-ietf-dnsop-dnssec-bootstrapping] |
   +---------+------------+-----------------------------------------+

8.  Implementation Status

   *Note to the RFC Editor*: please remove this entire section before
   publication.

   In addition to the information in this section, deployment is tracked
   by the community at https://github.com/oskar456/cds-updates
   (https://github.com/oskar456/cds-updates).



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8.1.  Child DNS Operator-side

   *  Operator support:

      -  Cloudflare has implemented bootstrapping record synthesis for
         all signed customer zones.

      -  Glauca HexDNS publishes bootstrapping records for its customer
         zones.

      -  deSEC performs bootstrapping record synthesis for its zones
         using names _signal.ns1.desec.io and _signal.ns2.desec.org.

   *  Authoritative nameserver support:

      -  An implementation of bootstrapping record synthesis in PowerDNS
         is available at https://github.com/desec-io/desec-ns/pull/46
         (https://github.com/desec-io/desec-ns/pull/46).

      -  Knot DNS supports manual creation of non-apex CDS/CDNSKEY
         records.

8.2.  Parental Agent-side

   *  ccTLD:

      -  SWITCH (.ch, .li) has implemented authentication of consumed
         CDS records based on this draft.

      -  .cl is working on an implementation.

   *  gTLD:

      -  Knipp has implemented consumption of DNSSEC bootstrapping
         records in its TANGO and CORE registry systems.

      -  A deployment of this is running at .swiss.

   *  Registrars:

      -  GoDaddy is working on an implementation.

      -  Glauca is working on an implementation.








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   *  A tool to retrieve and process Signaling Records for bootstrapping
      purposes, either directly or via zone walking, is available at
      https://github.com/desec-io/dsbootstrap (https://github.com/desec-
      io/dsbootstrap).  The tool outputs the validated DS records which
      then can be added to the Parent zone.

9.  Acknowledgements

   Thanks to Brian Dickson, Ondřej Caletka, John R.  Levine,
   Christian Elmerot, Oli Schacher, Donald Eastlake, Libor Peltan,
   Warren Kumari, Scott Rose, Linda Dunbar, Tim Wicinski for reviewing
   draft proposals and offering comments and suggestions.

   Thanks also to Steve Crocker, Hugo Salgado, and Ulrich Wisser for
   early-stage brainstorming.

10.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [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>.

   [RFC7344]  Kumari, W., Gudmundsson, O., and G. Barwood, "Automating
              DNSSEC Delegation Trust Maintenance", RFC 7344,
              DOI 10.17487/RFC7344, September 2014,
              <https://www.rfc-editor.org/info/rfc7344>.

   [RFC7477]  Hardaker, W., "Child-to-Parent Synchronization in DNS",
              RFC 7477, DOI 10.17487/RFC7477, March 2015,
              <https://www.rfc-editor.org/info/rfc7477>.





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   [RFC8078]  Gudmundsson, O. and P. Wouters, "Managing DS Records from
              the Parent via CDS/CDNSKEY", RFC 8078,
              DOI 10.17487/RFC8078, March 2017,
              <https://www.rfc-editor.org/info/rfc8078>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8499]  Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
              Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
              January 2019, <https://www.rfc-editor.org/info/rfc8499>.

   [RFC8552]  Crocker, D., "Scoped Interpretation of DNS Resource
              Records through "Underscored" Naming of Attribute Leaves",
              BCP 222, RFC 8552, DOI 10.17487/RFC8552, March 2019,
              <https://www.rfc-editor.org/info/rfc8552>.

11.  Informative References

   [RFC6781]  Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC
              Operational Practices, Version 2", RFC 6781,
              DOI 10.17487/RFC6781, December 2012,
              <https://www.rfc-editor.org/info/rfc6781>.

   [RFC8901]  Huque, S., Aras, P., Dickinson, J., Vcelak, J., and D.
              Blacka, "Multi-Signer DNSSEC Models", RFC 8901,
              DOI 10.17487/RFC8901, September 2020,
              <https://www.rfc-editor.org/info/rfc8901>.

Appendix A.  Change History (to be removed before publication)

   *  draft-ietf-dnsop-dnssec-bootstrapping-06

   |  Add section "Updates to RFCs"
   |  
   |  Editorial nits
   |  
   |  Editorial changes from Secdir early review

   *  draft-ietf-dnsop-dnssec-bootstrapping-05

   |  Editorial changes

   *  draft-ietf-dnsop-dnssec-bootstrapping-04

   |  Added consent considerations.
   |  



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   |  Editorial changes.

   *  draft-ietf-dnsop-dnssec-bootstrapping-03

   |  Updated Implementation section.
   |  
   |  Typo fix.

   *  draft-ietf-dnsop-dnssec-bootstrapping-02

   |  Clarified that RFC 8078 Section 3 is not replaced, but its methods
   |  are deprecated.
   |  
   |  Added new deployments to Implementation section.
   |  
   |  Included NSEC walk / AXFR as possible triggers for DS
   |  bootstrapping.
   |  
   |  Editorial changes.

   *  draft-ietf-dnsop-dnssec-bootstrapping-01

   |  Allow bootstrapping when some (not all) NS hostnames are in
   |  bailiwick.
   |  
   |  Clarified Operational Recommendations according to operator
   |  feedback.
   |  
   |  Turn loose Security Considerations points into coherent text.
   |  
   |  Do no longer suggest NSEC-walking Signaling Domains.  (It does not
   |  work well due to the Signaling Type prefix.  What's more, it's
   |  unclear who would do this: Parents know there delegations and can
   |  do a targeted scan; others are not interested.)
   |  
   |  Editorial changes.
   |  
   |  Added IANA request.
   |  
   |  Introduced Signaling Type prefix (_dsboot), renamed Signaling Name
   |  infix from _dsauth to _signal.

   *  draft-ietf-dnsop-dnssec-bootstrapping-00

   |  Editorial changes.

   *  draft-thomassen-dnsop-dnssec-bootstrapping-03




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   |  Clarified importance of record cleanup by moving paragraph up.
   |  
   |  Pointed out limitations.
   |  
   |  Replace [RFC8078] Section 3 with our Section 4.2.
   |  
   |  Changed _boot label to _dsauth.
   |  
   |  Removed hashing of Child name components in Signaling Names.
   |  
   |  Editorial changes.

   *  draft-thomassen-dnsop-dnssec-bootstrapping-02

   |  Reframed as an authentication mechanism for RFC 8078.
   |  
   |  Removed multi-signer use case (focus on RFC 8078 authentication).
   |  
   |  Triggers need to fetch NS records (if not implicit from context).
   |  
   |  Improved title.
   |  
   |  Recognized that hash collisions are dealt with by Child apex
   |  check.

   *  draft-thomassen-dnsop-dnssec-bootstrapping-01

   |  Add section on Triggers.
   |  
   |  Clarified title.
   |  
   |  Improved abstract.
   |  
   |  Require CDS/CDNSKEY records at the Child.
   |  
   |  Reworked Signaling Name scheme.
   |  
   |  Recommend using cold cache for consumption.
   |  
   |  Updated terminology (replace "Bootstrapping" by "Signaling").
   |  
   |  Added NSEC recommendation for Bootstrapping Zones.
   |  
   |  Added multi-signer use case.
   |  
   |  Editorial changes.

   *  draft-thomassen-dnsop-dnssec-bootstrapping-00



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   |  Initial public draft.

Authors' Addresses

   Peter Thomassen
   deSEC, Secure Systems Engineering
   Berlin
   Germany
   Email: peter@desec.io


   Nils Wisiol
   deSEC, Technische Universität Berlin
   Berlin
   Germany
   Email: nils@desec.io



































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