dnsop                                                          W. Kumari
Internet-Draft                                                    Google
Intended status: Informational                            O. Gudmundsson
Expires: October 16, 2014                                  Shinkuro Inc.
                                                              G. Barwood

                                                          April 14, 2014

             Automating DNSSEC Delegation Trust Maintenance


   This document describes a method to allow DNS operators to more
   easily update DNSSEC Key Signing Keys using the DNS as communication
   channel.  This document does not address the initial configuration of
   trust anchors for a domain.  The technique described is aimed at
   delegations in which it is currently hard to move information from
   the child to parent.

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 http://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 October 16, 2014.

Copyright Notice

   Copyright (c) 2014 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
   carefully, as they describe your rights and restrictions with respect

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   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.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Requirements Notation . . . . . . . . . . . . . . . . . .   4
   2.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  DNS Delegations . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Relationship Between Parent and Child DNS Operator  . . .   5
       2.2.1.  Solution Space  . . . . . . . . . . . . . . . . . . .   6
       2.2.2.  DNSSEC key change process . . . . . . . . . . . . . .   7
   3.  CDS / CDNSKEY (Child DS/ Child DNSKEY) Record Definitions . .   7
     3.1.  CDS Resource Record Format  . . . . . . . . . . . . . . .   8
     3.2.  CDNSKEY Resource Record Format  . . . . . . . . . . . . .   8
   4.  Automating DS Maintainance With CDS/CDNSKEY records . . . . .   8
     4.1.  CDS / CDNSKEY Processing Rules  . . . . . . . . . . . . .   8
   5.  CDS / CDNSKEY Publication . . . . . . . . . . . . . . . . . .   9
   6.  Parent Side CDS / CDNSKEY Consumption . . . . . . . . . . . .   9
     6.1.  Detecting a Changed CDS / CDNSKEY . . . . . . . . . . . .   9
       6.1.1.  CDS / CDNSKEY Polling . . . . . . . . . . . . . . . .  10
       6.1.2.  Other Mechanisms  . . . . . . . . . . . . . . . . . .  10
     6.2.  Using the New CDS / CDNSKEY Records . . . . . . . . . . .  11
       6.2.1.  Parent Calculates DS  . . . . . . . . . . . . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   8.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  12
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     11.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Appendix A.  RRR background . . . . . . . . . . . . . . . . . . .  15
   Appendix B.  Changes / Author Notes.  . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  19

1.  Introduction

   When a DNS operator first signs their zone, they need to communicate
   their DS record(s) (or DNSKEY(s)) to their parent through some out-
   of-band method to complete the chain of trust.

   Each time the child changes the key that is represented in the
   parent, the updated and/or deleted key information has to be
   communicated to the parent and published in the parent's zone.  How
   this information is sent to the parent depends on the relationship

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   the child has with the parent.  In many cases this is a manual
   process, and not an easy one.  For each key roll, there may be up to
   two interactions with the parent.  Any manual process is susceptible
   to mistakes and/or errors.  In addition, due to the annoyance factor
   of the process, operators may avoid performing key rollovers or skip
   needed steps to publish the new DS at the parent.

   DNSSEC provides data integrity to information published in DNS; thus
   DNS publication can be used to automate maintenance of delegation
   information.  This document describes a method to automate
   publication of subsequent DS records, after the initial one has been

   Readers are expected to be familiar with DNSSEC, including [RFC4033],
   [RFC4034], [RFC4035], [RFC5011] and [RFC6781].

   This document is a compilation of two earlier drafts: draft-barwood-
   dnsop-ds-publish[I-D.ds-publish] and draft-wkumari-dnsop-ezkeyroll.

   This document outlines a technique in which the parent periodically
   (or upon request) polls its signed children and automatically publish
   new DS records.  To a large extent, the procedures this document
   follows are as described in [RFC6781] section 4.1.2.

   This technique is designed to be friendly both to fully automated
   tools and humans.  Fully automated tools can perform all the actions
   needed without human intervention, and thus can monitor when it is
   safe to move to the next step.

   The solution described in this document only allows transferring
   information about DNSSEC keys (DS and DNSKEY) from the child to the
   parental agent.  It lists exactly what the parent should publish, and
   allows for publication of stand-by keys.  A different protocol,
   [I-D.csync], can be used to maintain other important delegation
   information, such as NS and glue.  These two protocols have been kept
   as separate solutions because the problems are fundamentally
   different, and a combined solution is overly complex.

   This document describes a method for automating maintanance of the
   delegation trust information, and proposes a polled / periodic
   trigger for simplicity.  Some users may prefer a different trigger,
   such as a button on a webpage, a REST interface, DNS NOTIFY, etc.
   These alternate / additional triggers are not discussed in this

   This proposal does not include all operations needed for the
   maintenance of DNSSEC key material, specifically the initial
   introduction or complete removal of all keys.  Because of this,

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   alternate communications mechanisms must always exist, potentially
   introducing more complexity.

1.1.  Terminology

   The terminology we use is defined in this section.

   Highlighted roles:

   o  Child: "The entity on record that has the delegation of the domain
      from the parent"

   o  Parent: "The domain in which the child is registered"

   o  Child DNS Operator: "The entity that maintains and publishes the
      zone information for the child DNS"

   o  Parent DNS Operator: "The entity that maintains and publishes the
      zone information for the parent DNS"

   o  Parental Agent: "The entity that the child has relationship with,
      to change its delegation information"

   o  Provisioning system: "A system that the operator of the master DNS
      server operates to maintain the information published in the DNS.
      This includes the systems that sign the DNS data"

   RRR is our shorthand for Registry/Registrar/Registrant model of
   parent child relationship see Appendix A for more.

1.2.  Requirements Notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

2.  Background

2.1.  DNS Delegations

   DNS operation consists of delegations of authority.  For each
   delegation there are (most of the time) two parties: the parent and
   the child.

   The parent publishes information about the delegations to the child;
   for the name servers it publishes an NS [RFC1035] RRset that lists a
   hint for name servers that are authoritative for the child.  The

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   child also publishes a NS RRset, and this set is the authoritative
   list of name servers to the child zone.

   The second RRset the parent sometimes publishes is the DS [RFC4034]
   set.  The DS RRset provides information about the DNSKEY(s) that the
   child has told the parent it will use to sign its DNSKEY RRset.  In
   DNSSEC trust relationship between zones is provided by the following

   parent DNSKEY --> DS --> child DNSKEY.

   A prior proposal [I-D.auto-cpsync] suggested that the child send an
   "update" to the parent via a mechanism similar to Dynamic Update.
   The main issue became: How does the child find the actual parental
   agent/server to send the update to?  While that could have been
   solved via technical means, it failed to each consensus.  There is
   also a similar proposal in [I-D.parent-zones].

   As the DS record can only be present at the parent ( [RFC4034]), some
   other method is needed to automate which DNSKEYs are picked to be
   represented in the parent zone's DS records.  One possibility is to
   use flags in the DNSKEY record.  If the SEP bit is set, this
   indicates that the DNSKEY is intended for use as a secure entry
   point.  This DNSKEY signs the DNSKEY RRset, and the Parental Agent
   can calculate DS records based on that.  But this fails to meet some
   operating needs, including the child having no influence what DS
   digest algorithms are used and DS records can only be published for
   keys that are in the DNSKEY RRset, and thus this technique would not
   be compatible with Double-DS key rollover.

2.2.  Relationship Between Parent and Child DNS Operator

   In practical application, there are many different relationships
   between the parent and child DNS operators.  The type of relationship
   affects how the Child DNS Operator communicates with the parent.
   This section will highlight some of the different situations, but is
   by no means a complete list.

   Different communication paths:

   o  Direct/API: The child can change the delegation information via
      automated/scripted means.  EPP[RFC5730], used by many TLDs is an
      example of this.  Another example is the web service's
      programmatic interfaces that Registrars make available to their

   o  User Interface: The Child uses a (web) site set up by the Parental
      Agent for updating delegation information.

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   o  Indirect: The communication has to be transmitted via out-of-band
      between two parties, such as email, telephone etc.. This is common
      when the Child's DNS operator is neither the child itself nor the
      Registrar for the domain but a third party.

   o  Multi-step Combinations: The information flows through an
      intermediary.  It is possible, but unlikely, that all the steps
      are automated via API's and there are no humans are involved.

   A domain name holder (Child) may operate its own DNS servers or
   outsource the operation.  While we use the word parent as a singular,
   parent can consist of single entity or a composite of many discrete
   parts that have rules and roles.  We refer to the entity that the
   child corresponds with as the Parent.

   IIn another common case an organization may delegate parts of its
   name-space to be operated by a group that is not the same as that
   which operates the organization's DNS servers.  In this case the flow
   of information is frequently handled in either an ad hoc manner or
   via some corporate mechanism; this can range from email to fully-
   automated operation.

2.2.1.  Solution Space

   This document is aimed at the cases in which there is a separation
   between the child and parent.

   A further complication is when the Child DNS Operator is not the
   Child.  There are two common cases of this:

   a)  The Parental Agent (e.g. registrar) handles the DNS operation.

   b)  A third party takes care of the DNS operation.

   If the Parental Agent is the DNS operator, life is much easier; the
   Parental Agent can inject any delegation changes directly into the
   Parent's Provisioning system.  The techniques described below are not
   needed in the case when Parental Agent is the DNS operator.

   In the case of a third party DNS operator, the Child either needs to
   relay changes in DNS delegation or give the Child DNS Operator access
   to its delegation/registration account.

   Some parents want the child to express their DNSKEYS in the form of
   DS records, while others want to receive the DNSKEY records and
   calculate the DS records themselves.  There is no consensus on which
   method is better; both have good reasons to exist.  This solution is
   DS vs DNSKEY agnostic, and allows operation with either.

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2.2.2.  DNSSEC key change process

   After a Child DNS Operator first signs the zone, there is a need to
   interact with the Parent, for example via a delegation account
   interface, to "upload / paste-in the zone's DS information".  This
   action of logging in through the delegation account user interface
   authenticates that the user is authorized to change delegation
   information for the child published in the parent zone.  In the case
   where the "Child DNS Operator" does not have access to the
   registration account, the Child needs to perform the action.

   At a later date, the Child DNS Operator may want to publish a new DS
   record in the parent, either because they are rolling keys, or
   because they want to publish a stand-by key.  This involves
   performing the same process as before.  Furthermore when this is a
   manual process with cut and paste, operational mistakes will happen
   -- or worse, the update action is not performed at all.

   The Child DNS Operator may also introduce new keys, and can do so
   when old keys exist and can be used.  The Child may also remove old
   keys, but this document does not support removing all keys.  This is
   to avoid making signed zones unsigned.  The Child may not enroll the
   initial key or introduce a new key when there are no old keys that
   can be used (without some additional, out of band, validation of the
   keys), because there is no way to validate the information.

3.  CDS / CDNSKEY (Child DS/ Child DNSKEY) Record Definitions

   This document specifies two new DNS resource records, CDS and
   CDNSKEY.  These records are used to convey, from one zone to its
   parent, the desired contents of the zone's DS resource record set
   residing in the parent zone.

   The CDS / CDNSKEY resource records are published in the child zone
   and gives the child control of what is published for it in the
   parental zone.  The CDS / CDNSKEY RRset expresses what the child
   would like the DS RRset to look like after the change; it is a
   "replace" operation, and it is up to the consumer of the records to
   translate that into the appropriate add/delete operations in the
   registration systems (and in the case of CDNSKEY, to generate the DS
   from the DNSKEY).  If no CDS / CDNSKEY RRset is present in child,
   this means that no change is needed.

   [[RFC Editor: Please remove this paragraph before publication]
   Version -04 of the ID that became this working group document (http:/
   /tools.ietf.org/id/draft-kumari-ogud-dnsop-cds-04.txt) defined a new
   record (CTA) that could hold either a DS or a DNSKEY record (with a

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   selector to differentiate between them).  In a shocking development,
   there was almost full consensus that this was horrid :-) ]

3.1.  CDS Resource Record Format

   The wire and presentation format of the CDS ("Child DS") resource
   record is identical to the DS record [RFC4034].  IANA has allocated
   RR code 59 for the CDS resource record via expert review
   [I-D.ds-publish].  The CDS RR uses the same registries as DS for its

   No special processing is performed by authoritative servers or by
   revolvers, when serving or resolving.  For all practical purposes CDS
   is a regular RR type.

3.2.  CDNSKEY Resource Record Format

   The wire and presentation format of the CDNSKEY ("Child DNSKEY")
   resource record is identical to the DNSKEY record.  IANA has
   allocated RR code TBA1 for the CDNSKEY resource record via expert
   review.  The CDNSKEY RR uses the same registries as DNSKEY for its

   No special processing is performed by authoritative servers or by
   revolvers, when serving or resolving.  For all practical purposes
   CDNSKEY is a regular RR type.

4.  Automating DS Maintainance With CDS/CDNSKEY records

   CDS/CDNSKEY resource records are intended to be "consumed" by
   delegation trust maintainers.  The use of CDS/CDNSKEY is optional.

   The child SHOULD publish both CDS and CDNSKEY resource records.  If
   the child knows which the parent consumes, it MAY choose to only
   publish that record type (for example, some children wish the parent
   to publish a DS, but they wish to keep the DNSKEY "hidden" until
   needed).  If the child publishes both, the two RRsets MUST match in
   content.  The parent should use whichever one they choose, but MUST
   NOT query for both and perform consistency checks between the CDS and
   CDNSKEY resource records.

4.1.  CDS / CDNSKEY Processing Rules

   If there are no CDS / CDNSKEY RRset in the child, this signals that
   no change should be made to the current DS set.  This means that,
   once the child and parent are in sync, the child DNS operator MAY
   remove all CDS and CDNSKEY resource records from the zone.

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   Following acceptance rules are placed on the CDS / CDNSKEY resource
   records as follows:

   o  Location: "the CDS / CDNSKEY resource records MUST be at the child
      zone apex".

   o  Signer: "MUST be signed with a key that is represented in both the
      current DNSKEY and DS RRset's."

   o  Continuity: "MUST NOT break the current delegation if applied to
      DS RRset"

   If any these conditions fail the CDS / CDNSKEY resource record MUST
   be ignored.

5.  CDS / CDNSKEY Publication

   Child DNS Operator publishes a CDS and / or CDNSKEY resource records.
   In order to be valid, the CDS / CDNSKEY RRset MUST be compliant with
   the rules in Section 4.1.  When the Parent DS is "in-sync" with the
   CDS / CDNSKEY resource records, the Child DNS Operator MAY delete the
   CDS / CDNSKEY record(s); the child can determine if this is the case
   by quering for DS records in the parent.  Note that if the child has
   published a CDNSKEY RR, the Parent will have to calculate the DS
   (using the requested digest algorithm) to do the comparison.

6.  Parent Side CDS / CDNSKEY Consumption

   The CDS / CDNSKEY RRset SHOULD be used by the Parental Agent to
   update the DS RRset in the parent zone.  The Parental Agent for this
   uses a tool that understands the CDS / CDNSKEY signing rules from
   Section 4.1 so it may not be able to use a standard validator.

   The parent MUST choose to accept either CDS or CDNSKEY resource
   records (based upon local policy), and MUST NOT expect there to be
   both.  A parent MUST NOT perform a consistency check between CDS and
   CDNSKEY (other than for informational / debugging use) resource

6.1.  Detecting a Changed CDS / CDNSKEY

   How the Parental Agent gets the CDS / CDNSKEY RRset may differ, below
   are two examples as how this can take place.

   Polling  The Parental Agent operates a tool that periodically checks
         each of the children that has a DS record to see if there is a
         CDS or CDNSKEY RRset.

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   Pushing  The delegation user interface has a button {Fetch DS} when
         pushed preforms the CDS / CDNSKEY processing.  If the Parent
         zone does not contain DS for this delegation then the "push"
         SHOULD be ignored.  If the Parental Agent displays the contents
         of the CDS / CDSNKEY to the user and gets confirmation that
         this represents their key, the Parental Agent MAY use this for
         initial enrolment (when the Parent zone does not contain the DS
         for this delgation).

   In either case the Parental Agent MAY apply additional rules that
   defer the acceptance of a CDS / CDNSKEY change, these rules may
   include a condition that the CDS / CDNSKEY remains in place and valid
   for some time period before it is accepted.  It may be appropriate in
   the "Pushing" case to assume that the Child is ready and thus accept
   changes without delay.

6.1.1.  CDS / CDNSKEY Polling

   This is the only defined use of CDS / CDNSKEY resource records in
   this document.  There are limits to the scaleability of polling
   techniques, thus some other mechanism is likely to be specified later
   that addresses CDS / CDNSKEY resource recod usage in the situation
   where polling does not scale to.  Having said that Polling will work
   in many important cases like enterprises, universities, small TLDs
   etc.  In many regulatory environments the registry is prohibited from
   talking to the registrant.  In most of these cases the registrant has
   a business relationship with the registrar, and so the registrar can
   offer this as a service.

   If the CDS / CDNSKEY RRset does not exist, the Parental Agent MUST
   take no action.  Specifically it MUST NOT delete or alter the
   existing DS RRset.

6.1.2.  Other Mechanisms

   It is assumed that other mechanisms will be implemented to trigger
   the parent to look for an updated CDS / CDNSKEY RRsets.  As the CDS /
   CDNSKEY resource records are validated with DNSSEC, these mechanisms
   can be unauthenticated (for example, a child could telephone its
   parent and request that they process the new CDS or CDNSKEY resource
   records, an unauthenticated POST could be made to a webserver (with
   rate-limiting), etc.)

   Other documents can specify the trigger conditions.

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6.2.  Using the New CDS / CDNSKEY Records

   Regardless of how the Parental Agent detected changes to a CDS /
   CDNSKEY RRset, the Parental Agent SHOULD use a DNSSEC validator to
   obtain a validated CDS / CDNSKEY RRset from the Child zone.  The only
   exception to this is if the parent perfoms some additional validation
   on the data to confirm that it is the "correct" key.  This behavior

   The Parental Agent MUST ensure that old versions of the CDS / CDNSKEY
   RRset do not overwrite newer versions.  This MAY be accomplished by
   checking that the signature inception in the RRSIG for CDS / CDNSKEY
   RRset is newer and/or the serial number on the child's SOA is
   greater.  This may require the Parental Agent to maintain some state

   The Parental Agent MAY take extra security measures.  For example, to
   mitigate the possibility that a Child's key signing key has been
   compromised, the Parental Agent may, for example, inform (by email or
   other methods ) the Child DNS Operator of the change.  However the
   precise out-of-band measures that a parent zone SHOULD take are
   outside the scope of this document.

   Once the Parental Agent has obtained a valid CDS / CDNSKEY RRset it
   MUST check the publication rules from section 4.1.  In particular the
   Parental Agent MUST double check the Continuity rule and do its best
   not to invalidate the Child zone.  Once checked and if the
   information in the CDS / CDNSKEY and DS differ it may apply the
   changes to the parent zone.  If the parent consumes CDNSKEY, the
   parent should calculate the DS before doing this comparison.

6.2.1.  Parent Calculates DS

   There are cases where the Parent wants to calculate the DS record due
   to policy reasons.  In this case, the Child publishes CDNSKEY records
   and the parent calculates the DS records on behalf of the children.

   When a Parent operates in "calculate DS" mode it can operate in one
   of two sub-modes

   full  it only publishes DS records it calculates from DNSKEY records,

   augment  it will make sure there are DS records for the digest
      algorithm(s) it requires(s).

   In the case where the parent fetches the CDNSKEY RRset and calculate
   the DS it MAY be the case that the DS published in the parent zone is

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   not identical with the data in the CDS resource record made available
   by the child.

7.  IANA Considerations

   IANA has assigned RR Type code 59 for the CDS resource record.  This
   was done for an earlier version of this document[I-D.ds-publish] This
   document is to become the reference for CDS RRtype.

   IANA is requested to assign another RR Type for the CDNSKEY, and to
   replace TBA1 with this value (currntly 60 is still free, it would be
   nice if that were assigned...)

8.  Privacy Considerations

   All of the information handled / transmitted by this protocol is
   public information published in the DNS.

9.  Security Considerations

   This work is for the normal case; when things go wrong there is only
   so much that automation can fix.

   If child breaks DNSSEC validation by removing all the DNSKEYs that
   are represented in the DS set its only repair actions are to contact
   the parent or restore the DNSKEYs in the DS set.

   In the event of a compromise of the server or system generating
   signatures for a zone, an attacker might be able to generate and
   publish new CDS resource records.  The modified CDS recourse records
   will be picked up by this technique and so may allow the attacker to
   extend the effective time of his attack.  If there a delay in
   accepting changes to DS, as in [RFC5011], then the attacker needs to
   hope his activity is not detected before the DS in parent is changed.
   If this type of change takes place, the child needs to contact the
   parent (possibly via a registrar web interface) and remove any
   compromised DS keys.

   A compromise of the account with the parent (e.g. registrar) will not
   be mitigated by this technique, as the "new registrant" can delete/
   modify the DS records at will.

   While it may be tempting, this SHOULD NOT be used for initial
   enrollment of keys since there is no way to ensure that the initial
   key is the correct one.  If is used, strict rules for inclusion of
   keys like hold down times, challenge data inclusion etc., ought to be
   used, along with some kind of challenge mechanism.  A child cannot

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   use this mechanism to go from signed to unsigned (publishing an empty
   CDS / CDNSKEY RRset means no-change should be made in the parent).

   The CDS RR type should allow for enhanced security by simplifying
   process.  Since rollover is automated, updating a DS RRset by other
   means may be regarded as unusual and subject to extra security

   As this introduces a new mechanism to update information in the
   parent it MUST be clear who is fetching the records and creating the
   appropriate records in the parent zone.  Specifically some operations
   may use other mechanisms than what is described here.  For example, a
   registrar may assume that it is maintaining the DNSSEC key
   information in the registry, and may have this cached.  If the
   registry is fetching the CDS / CDNSKEY RRset then the registry and
   registrar may have different views of the DNSSEC key material and the
   result of such a situation is unclear.  Therefore, this mechanism
   SHOULD NOT be use to bypass intermediaries that might cache
   information and because of that get the wrong state.

   If there is a failure in applying changes in child zone to all DNS
   servers listed in either parent or child NS set it is possible that
   the Parental agent may get confused, either because it gets different
   answers on different checks or CDS RR validation fails.  In the worst
   case, the Parental Agent performs an action reversing a prior action
   but after the child signing system decides to take the next step in
   rollover, resulting in a broken delegation.

   DNS is a loosely coherent distributed database with local caching;
   therefore, it is important to allow old information to expire from
   caches before deleting DS or DNSKEY records.  Similarly, it is
   important to allow new records to propagate through the DNS before
   use, see [RFC6781] and [I-D.key-time]

   It is common practice for users to outsource their DNS hosting to a
   3rd party DNS provider.  In order for that provider to be able to
   maintain the DNSSEC information some users give the provider their
   registrar login credentials (which obviously has negative security
   implications).  Deploying the solution described in this document
   allows the 3rd party DNS provider to maintain the DNSSEC information
   without giving them the registrar credentials, thereby improving

   By automating the maintenance of the DNSSEC key information (and
   removing humans from the process), we expect to decrease the number
   of DNSSEC related outages, which should increase DNSSEC deployment.

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10.  Acknowledgements

   We would like to thank a large number of folk, including: Mark
   Andrews, Joe Abley, Jaap Akkerhuis, Roy Arends, Doug Barton, Brian
   Dickinson, Paul Ebersman, Tony Finch, Jim Galvin, Paul Hoffman, Samir
   Hussain, Tatuya Jinmei, Olaf Kolkman, Cricket Liu, Stephan Lagerholm,
   Matt Larson, Marco Sanz, Antoin Verschuren, Suzanne Woolf, Paul
   Wouters, John Dickinson, Timothe Litt and Edward Lewis.

   Special thanks to Wes Hardaker for contributing significant text and
   creating the complementary (CSYNC) solution, and to Patrik Faltstrom,
   Paul Hoffman, Matthijs Mekking and Mukund Sivaraman for text and in-
   depth review.

   There were a number of other folk with whom we discussed this,
   apologies for not remembering everyone.

11.  References

11.1.  Normative References

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements", RFC
              4033, March 2005.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, March 2005.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, March 2005.

   [RFC5011]  StJohns, M., "Automated Updates of DNS Security (DNSSEC)
              Trust Anchors", STD 74, RFC 5011, September 2007.

   [RFC6781]  Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC
              Operational Practices, Version 2", RFC 6781, December

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11.2.  Informative References

              Mekking, W., "Automated (DNSSEC) Child Parent
              Synchronization using DNS UPDATE", draft-mekking-dnsop-
              auto-cpsync-01 (work in progress), December 2010.

              Hardaker, W., "Child To Parent Synchronization in DNS",
              draft-hardaker-dnsop-csync-02 (work in progress), July

              Barwood, G., "DNS Transport", draft-barwood-dnsop-ds-
              publish-02 (work in progress), June 2011.

              Mekking, W., "DNSSEC Key Timing Considerations", draft-
              ietf-dnsop-dnssec-key-timing-03 (work in progress), July

              Andrews, M., "Updating Parent Zones", draft-andrews-dnsop-
              update-parent-zones-04 (work in progress), November 2013.

   [RFC5730]  Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
              STD 69, RFC 5730, August 2009.

   [RFC5910]  Gould, J. and S. Hollenbeck, "Domain Name System (DNS)
              Security Extensions Mapping for the Extensible
              Provisioning Protocol (EPP)", RFC 5910, May 2010.

Appendix A.  RRR background

   In the RRR world, the different parties are frequently from different
   organizations.  In the single enterprise world there are also
   organizational/geographical/cultural separations that affect how
   information flows from a Child to the parent.

   Due to the complexity of the different roles and interconnections,
   automation of delegation information has not yet occured.  There have
   been proposals to automate this, in order to improve the reliability
   of the DNS.  These proposals have not gained enough traction to
   become standards.

   For example in many of the TLD cases there is the RRR model
   (Registry, Registrar and Registrant).  The Registry operates DNS for
   the TLD, the Registrars accept registrations and place information

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   into the Registries database.  The Registrant only communicates with
   the Registrar; frequently the Registry is not allowed to communicate
   with the Registrant.  In that case as far as the registrant is
   concerned the Registrar == Parent.

   In many RRR cases the Registrar and Registry communicate via
   EPP[RFC5730] and use the EPP DNSSEC extension [RFC5910].  In a number
   of ccTLDs there are other mechanisms in use as well as EPP, but in
   general there seems to be a movement towards EPP usage when DNSSEC is
   enabled in the TLD.

Appendix B.  Changes / Author Notes.

   [RFC Editor: Please remove this section before publication ]

   WG-06 to WG-07

   o  Incorporated nits / editorial comments from Tim Wicinski.


      *  Reference for Mark's draft was incorrect, Wes Hardaker doesn't
         work for ISC :-P

      *  Normalized CDS record / CDS resource record / records / etc.

      *  Language cleanup / nits / poor grammar.

      *  removed "punted" colloquialism.

   WG-05 to WG-06

   o  Consensus (according to me!) was that mail thread said "Child MAY
      remove the CDS record".  Changed to accomodate.

   o  "The proposal below can operate with both models, but the child
      needs to be aware of the parental policies." - removed "but the
      child needs to be aware of the parental policies.".  This is no
      longer true, as we suggest publishing both CDS and CDSNKEY.

   o  Added: "without some additional out of band process" to "The Child
      may not enroll the initial key or introduce a new key when there
      are no old keys that can be used (without some additional, out of
      band, validation of the keys), because there is no way to validate
      the information."

   o  Added a bit to the IANA section, requesting that TBA1 be replaced
      with the IANA allocated code.

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   o  Removed" Some parents prefer to accept DNSSEC key information in
      DS format, some parents prefer to accept it in DNSKEY format, and
      calculate the DS record on the child's behalf.  Each method has
      pros and cons, both technical and policy.  This solution is DS vs
      DNSKEY agnostic, and allows operation with either." from Section 4
      as it is covered in Section 2.2.1

   o  Remove a bunch of comments from the XML.  I was getting tired of
      scrolling past them.  If the authors need them back, they are in
      SVN commit 47.

   WG-04 to WG-05

   o  More comments from Patrik, Paul and Ed.

   o  Many nits and fixes from Matthijs Mekking.

   o  Outstanding question: Should we remove the "Child SHOULD remove
      the CDS record" text?  Mail sent to list.

   WG-03 to WG-04

   o  Large number of comments and changes from Patrik.

   WG-02 to WG-03

   o  Fixed some references to RFC 5011 - from Samir Hussain.

   o  Fixed some spelling / typos - from Samir Hussain.

   o  A number of clarifiations on the meaning on an empty / non-
      existant CDS RRset - thanks to JINMEI, Tatuya

   o  Be consistent in mentioning both CDS and CDNSKEY throughout the

   WG-01 to WG-02

   o  Many nits and suggestions from Mukund.

   o  Matthijs: " I still think that it is too strong that the Child DNS
      Operator SHOULD/MUST delete the CDS RRset when the Parent DS is
      "in-sync".  This should be a MAY"

   WG-00 to WG-01

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   o  Addressed Vancouver: "Paul Hoffmann: NOT ready for WGLC.  None of
      the 2 documents explain why there is a split between the two
      strategies."  Thanks to Paul for providing text.

   From -05 to WG-00:

   o  Nothing rchanged, resubmit under new name.

   From 04 to 05

   o  Renamed the record back to CDS.

   From 03 to 04.

   o  Added text explaining that CDS and CSYNC complement each other,
      not replace or compete.

   o  Changed format of record to be <selector> <data> to allow the
      publication of DS **or** DNSKEY.

   o  Bunch of text changed to cover the above.

   o  Added a bit more text on the polling scaling stuff, expectation
      that other triggers will be documented.

   From 02 to 03

   o  Applied comments by Matthijs Mekking

   o  Incorporated suggestions from Edward Lewis about structure

   o  Reworked structure to be easier for implementors to follow

   o  Applied many suggestions from a wonderful thorough review by John

   o  Removed the going Unsigned option

   From 01 to 02

   o  Major restructuring to facilitate easier discussion

   o  Lots of comments from DNSOP mailing list incorporated, including
      making draft DNSKEY/DS neutral, explain different relationships
      that exists,

   o  added more people to acks.

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   o  added description of enterprise situations

   o  Unified on using Parental Agent over Parental Representative

   o  Removed redundant text when possible

   o  Added text to explain what can go wrong if not all child DNS
      servers are in sync.

   o  Reference prior work by Matthijs Mekking

   o  Added text when parent calculates DS from DNSKEY

   From - to -1.

   o  Removed from section .1: "If a child zone has gone unsigned, i.e.
      no DNSKEY and no RRSIG in the zone, the parental representative
      MAY treat that as intent to go unsigned.  (NEEDS DISCUSSION)."
      Added new text at end. -- suggestion by Scott Rose 20/Feb/13.

   o  Added some background on the different DNS Delegation operating
      situations and how they affect interaction of parties.  This moved
      some blocks of text from later sections into here.

   o  Number of textual improvements from Stephan Lagerholm

   o  Added motivation why CDS is needed in CDS definition section

   o  Unified terminology in the document.

   o  Much more background

Authors' Addresses

   Warren Kumari
   1600 Amphitheatre Parkway
   Mountain View, CA  94043

   Email: warren@kumari.net

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   Olafur Gudmundsson
   Shinkuro Inc.
   4922 Fairmont Av, Suite 250
   Bethesda, MD  20814

   Email: ogud@ogud.com

   George Barwood
   33 Sandpiper Close
   Gloucester  GL2 4LZ
   United Kingdom

   Email: george.barwood@blueyonder.co.uk

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