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doc/draft/draft-ietf-dnsext-dnssec-bis-updates-10.txt → doc/draft/draft-ietf-dnsext-dnssec-bis-updates-12.txt
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@@ -5,12 +5,12 @@ Network Working Group S. Weiler
Internet-Draft SPARTA, Inc. Internet-Draft SPARTA, Inc.
Updates: 4033, 4034, 4035, 5155 D. Blacka Updates: 4033, 4034, 4035, 5155 D. Blacka
(if approved) VeriSign, Inc. (if approved) VeriSign, Inc.
Intended status: Standards Track March 8, 2010 Intended status: Standards Track November 10, 2010
Expires: September 9, 2010 Expires: May 14, 2011
Clarifications and Implementation Notes for DNSSECbis Clarifications and Implementation Notes for DNSSECbis
draft-ietf-dnsext-dnssec-bis-updates-10 draft-ietf-dnsext-dnssec-bis-updates-12
Abstract Abstract
@@ -20,26 +20,20 @@ Abstract
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF). Note that other groups may also distribute
other groups may also distribute working documents as Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at This Internet-Draft will expire on May 14, 2011.
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 9, 2010.
Copyright Notice Copyright Notice
@@ -49,20 +43,18 @@ Copyright Notice
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
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publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the BSD License. described in the Simplified BSD License.
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Table of Contents Table of Contents
@@ -72,45 +64,53 @@ Table of Contents
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Important Additions to DNSSSECbis . . . . . . . . . . . . . . 3 2. Important Additions to DNSSSECbis . . . . . . . . . . . . . . 3
2.1. NSEC3 Support . . . . . . . . . . . . . . . . . . . . . . 3 2.1. NSEC3 Support . . . . . . . . . . . . . . . . . . . . . . 3
2.2. SHA-256 Support . . . . . . . . . . . . . . . . . . . . . 4 2.2. SHA-2 Support . . . . . . . . . . . . . . . . . . . . . . 4
3. Security Concerns . . . . . . . . . . . . . . . . . . . . . . 4 3. Scaling Concerns . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Clarifications on Non-Existence Proofs . . . . . . . . . . 4 3.1. Implement a BAD cache . . . . . . . . . . . . . . . . . . 4
3.2. Validating Responses to an ANY Query . . . . . . . . . . . 5 4. Security Concerns . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Check for CNAME . . . . . . . . . . . . . . . . . . . . . 5 4.1. Clarifications on Non-Existence Proofs . . . . . . . . . . 4
3.4. Insecure Delegation Proofs . . . . . . . . . . . . . . . . 5 4.2. Validating Responses to an ANY Query . . . . . . . . . . . 5
4. Interoperability Concerns . . . . . . . . . . . . . . . . . . 5 4.3. Check for CNAME . . . . . . . . . . . . . . . . . . . . . 5
4.1. Errors in Canonical Form Type Code List . . . . . . . . . 5 4.4. Insecure Delegation Proofs . . . . . . . . . . . . . . . . 5
4.2. Unknown DS Message Digest Algorithms . . . . . . . . . . . 6 5. Interoperability Concerns . . . . . . . . . . . . . . . . . . 5
4.3. Private Algorithms . . . . . . . . . . . . . . . . . . . . 6 5.1. Errors in Canonical Form Type Code List . . . . . . . . . 6
4.4. Caution About Local Policy and Multiple RRSIGs . . . . . . 7 5.2. Unknown DS Message Digest Algorithms . . . . . . . . . . . 6
4.5. Key Tag Calculation . . . . . . . . . . . . . . . . . . . 7 5.3. Private Algorithms . . . . . . . . . . . . . . . . . . . . 6
4.6. Setting the DO Bit on Replies . . . . . . . . . . . . . . 7 5.4. Caution About Local Policy and Multiple RRSIGs . . . . . . 7
4.7. Setting the AD Bit on Queries . . . . . . . . . . . . . . 8 5.5. Key Tag Calculation . . . . . . . . . . . . . . . . . . . 7
4.8. Setting the AD Bit on Replies . . . . . . . . . . . . . . 8 5.6. Setting the DO Bit on Replies . . . . . . . . . . . . . . 8
4.9. Setting the CD bit on Requests . . . . . . . . . . . . . . 8 5.7. Setting the AD Bit on Queries . . . . . . . . . . . . . . 8
4.10. Nested Trust Anchors . . . . . . . . . . . . . . . . . . . 8 5.8. Setting the AD Bit on Replies . . . . . . . . . . . . . . 8
4.10.1. Closest Encloser . . . . . . . . . . . . . . . . . . 9 5.9. Handling Queries With the CD Bit Set . . . . . . . . . . . 8
4.10.2. Accept Any Success . . . . . . . . . . . . . . . . . 9 5.10. Nested Trust Anchors . . . . . . . . . . . . . . . . . . . 9
4.10.3. Preference Based on Source . . . . . . . . . . . . . 10 5.10.1. Closest Encloser . . . . . . . . . . . . . . . . . . 9
5. Minor Corrections and Clarifications . . . . . . . . . . . . . 10 5.10.2. Accept Any Success . . . . . . . . . . . . . . . . . 9
5.1. Finding Zone Cuts . . . . . . . . . . . . . . . . . . . . 10 5.10.3. Preference Based on Source . . . . . . . . . . . . . 10
5.2. Clarifications on DNSKEY Usage . . . . . . . . . . . . . . 10 6. Minor Corrections and Clarifications . . . . . . . . . . . . . 10
5.3. Errors in Examples . . . . . . . . . . . . . . . . . . . . 11 6.1. Finding Zone Cuts . . . . . . . . . . . . . . . . . . . . 10
5.4. Errors in RFC 5155 . . . . . . . . . . . . . . . . . . . . 11 6.2. Clarifications on DNSKEY Usage . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 6.3. Errors in Examples . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 6.4. Errors in RFC 5155 . . . . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8.1. Normative References . . . . . . . . . . . . . . . . . . . 12 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . . 13 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 13 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction and Terminology 1. Introduction and Terminology
@@ -158,37 +158,47 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
Family as described by [RFC4033], Section 10. Family as described by [RFC4033], Section 10.
Note that the algorithm identifiers defined in RFC5155 (DSA-NSEC3- Note that the algorithm identifiers defined in RFC5155 (DSA-NSEC3-
SHA1 and RSASHA1-NSEC3-SHA1) signal that a zone MAY be using NSEC3, SHA1 and RSASHA1-NSEC3-SHA1) and RFC5702 (RSASHA256 and RSASHA512)
rather than NSEC. The zone MAY indeed be using either and validators signal that a zone MAY be using NSEC3, rather than NSEC. The zone
supporting these algorithms MUST support both NSEC3 and NSEC MAY indeed be using either and validators supporting these algorithms
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responses. MUST support both NSEC3 and NSEC responses.
2.2. SHA-256 Support 2.2. SHA-2 Support
[RFC4509] describes the use of SHA-256 as a digest algorithm in [RFC4509] describes the use of SHA-256 as a digest algorithm in
Delegation Signer (DS) RRs. [RFC5702] describes the use of the Delegation Signer (DS) RRs. [RFC5702] describes the use of the
RSASHA256 algorithm in DNSKEY and RRSIG RRs. Validator RSASHA256 and RSASHA512 algorithms in DNSKEY and RRSIG RRs.
implementations are strongly encouraged to include support for this Validator implementations are strongly encouraged to include support
algorithm for DS, DNSKEY, and RRSIG records. for these algorithms for DS, DNSKEY, and RRSIG records.
Both [RFC4509] and [RFC5702] should also be considered part of the Both [RFC4509] and [RFC5702] should also be considered part of the
DNS Security Document Family as described by [RFC4033], Section 10. DNS Security Document Family as described by [RFC4033], Section 10.
3. Security Concerns 3. Scaling Concerns
3.1. Implement a BAD cache
Section 4.7 of RFC4035 permits security-aware resolvers to implement
a BAD cache. Because of scaling concerns not discussed in this
document, that guidance has changed: security-aware resolvers SHOULD
implement a BAD cache, as described in RFC4035.
4. Security Concerns
This section provides clarifications that, if overlooked, could lead This section provides clarifications that, if overlooked, could lead
to security issues. to security issues.
3.1. Clarifications on Non-Existence Proofs 4.1. Clarifications on Non-Existence Proofs
[RFC4035] Section 5.4 under-specifies the algorithm for checking non- [RFC4035] Section 5.4 under-specifies the algorithm for checking non-
existence proofs. In particular, the algorithm as presented would existence proofs. In particular, the algorithm as presented would
@@ -207,6 +217,14 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
that (original) owner name other than DS RRs, and all RRs below that that (original) owner name other than DS RRs, and all RRs below that
owner name regardless of type. owner name regardless of type.
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Similarly, the algorithm would also allow an NSEC RR at the same Similarly, the algorithm would also allow an NSEC RR at the same
owner name as a DNAME RR, or an NSEC3 RR at the same original owner owner name as a DNAME RR, or an NSEC3 RR at the same original owner
name as a DNAME, to prove the non-existence of names beneath that name as a DNAME, to prove the non-existence of names beneath that
@@ -214,18 +232,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
to assume the non-existence of any subdomain of that NSEC/NSEC3 RR's to assume the non-existence of any subdomain of that NSEC/NSEC3 RR's
(original) owner name. (original) owner name.
4.2. Validating Responses to an ANY Query
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3.2. Validating Responses to an ANY Query
[RFC4035] does not address how to validate responses when QTYPE=*. [RFC4035] does not address how to validate responses when QTYPE=*.
As described in Section 6.2.2 of [RFC1034], a proper response to As described in Section 6.2.2 of [RFC1034], a proper response to
@@ -241,7 +248,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
To be clear, a validator must not expect to receive all records at To be clear, a validator must not expect to receive all records at
the QNAME in response to QTYPE=*. the QNAME in response to QTYPE=*.
3.3. Check for CNAME 4.3. Check for CNAME
Section 5 of [RFC4035] says little about validating responses based Section 5 of [RFC4035] says little about validating responses based
on (or that should be based on) CNAMEs. When validating a NOERROR/ on (or that should be based on) CNAMEs. When validating a NOERROR/
@@ -250,7 +257,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
type. Without this check, an attacker could successfully transform a type. Without this check, an attacker could successfully transform a
positive CNAME response into a NOERROR/NODATA response. positive CNAME response into a NOERROR/NODATA response.
3.4. Insecure Delegation Proofs 4.4. Insecure Delegation Proofs
[RFC4035] Section 5.2 specifies that a validator, when proving a [RFC4035] Section 5.2 specifies that a validator, when proving a
delegation is not secure, needs to check for the absence of the DS delegation is not secure, needs to check for the absence of the DS
@@ -263,9 +270,18 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
not signed. not signed.
4. Interoperability Concerns 5. Interoperability Concerns
4.1. Errors in Canonical Form Type Code List
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5.1. Errors in Canonical Form Type Code List
When canonicalizing DNS names, DNS names in the RDATA section of NSEC When canonicalizing DNS names, DNS names in the RDATA section of NSEC
and RRSIG resource records are not downcased. and RRSIG resource records are not downcased.
@@ -273,14 +289,6 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
[RFC4034] Section 6.2 item 3 has a list of resource record types for [RFC4034] Section 6.2 item 3 has a list of resource record types for
which DNS names in the RDATA are downcased for purposes of DNSSEC which DNS names in the RDATA are downcased for purposes of DNSSEC
canonical form (for both ordering and signing). That list canonical form (for both ordering and signing). That list
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erroneously contains NSEC and RRSIG. According to [RFC3755], DNS erroneously contains NSEC and RRSIG. According to [RFC3755], DNS
names in the RDATA of NSEC and RRSIG should not be downcased. names in the RDATA of NSEC and RRSIG should not be downcased.
@@ -288,7 +296,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
Since HINFO records contain no domain names, they are not subject to Since HINFO records contain no domain names, they are not subject to
downcasing. downcasing.
4.2. Unknown DS Message Digest Algorithms 5.2. Unknown DS Message Digest Algorithms
Section 5.2 of [RFC4035] includes rules for how to handle delegations Section 5.2 of [RFC4035] includes rules for how to handle delegations
to zones that are signed with entirely unsupported public key to zones that are signed with entirely unsupported public key
@@ -317,10 +325,18 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
disregards any DS records using unknown or unsupported message digest disregards any DS records using unknown or unsupported message digest
algorithms. algorithms.
4.3. Private Algorithms 5.3. Private Algorithms
As discussed above, section 5.2 of [RFC4035] requires that validators As discussed above, section 5.2 of [RFC4035] requires that validators
make decisions about the security status of zones based on the public make decisions about the security status of zones based on the public
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key algorithms shown in the DS records for those zones. In the case key algorithms shown in the DS records for those zones. In the case
of private algorithms, as described in [RFC4034] Appendix A.1.1, the of private algorithms, as described in [RFC4034] Appendix A.1.1, the
eight-bit algorithm field in the DS RR is not conclusive about what eight-bit algorithm field in the DS RR is not conclusive about what
@@ -329,17 +345,9 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
If no private algorithms appear in the DS set or if any supported If no private algorithms appear in the DS set or if any supported
algorithm appears in the DS set, no special processing will be algorithm appears in the DS set, no special processing will be
needed. In the remaining cases, the security status of the zone needed. In the remaining cases, the security status of the zone
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depends on whether or not the resolver supports any of the private depends on whether or not the resolver supports any of the private
algorithms in use (provided that these DS records use supported hash algorithms in use (provided that these DS records use supported hash
functions, as discussed in Section 4.2). In these cases, the functions, as discussed in Section 5.2). In these cases, the
resolver MUST retrieve the corresponding DNSKEY for each private resolver MUST retrieve the corresponding DNSKEY for each private
algorithm DS record and examine the public key field to determine the algorithm DS record and examine the public key field to determine the
algorithm in use. The security-aware resolver MUST ensure that the algorithm in use. The security-aware resolver MUST ensure that the
@@ -351,7 +359,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
This clarification facilitates the broader use of private algorithms, This clarification facilitates the broader use of private algorithms,
as suggested by [RFC4955]. as suggested by [RFC4955].
4.4. Caution About Local Policy and Multiple RRSIGs 5.4. Caution About Local Policy and Multiple RRSIGs
When multiple RRSIGs cover a given RRset, [RFC4035] Section 5.3.3 When multiple RRSIGs cover a given RRset, [RFC4035] Section 5.3.3
suggests that "the local resolver security policy determines whether suggests that "the local resolver security policy determines whether
@@ -370,30 +378,30 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
method described in section 4.2.1.2 of [RFC4641] might not work method described in section 4.2.1.2 of [RFC4641] might not work
reliably. reliably.
4.5. Key Tag Calculation 5.5. Key Tag Calculation
[RFC4034] Appendix B.1 incorrectly defines the Key Tag field [RFC4034] Appendix B.1 incorrectly defines the Key Tag field
calculation for algorithm 1. It correctly says that the Key Tag is calculation for algorithm 1. It correctly says that the Key Tag is
the most significant 16 of the least significant 24 bits of the the most significant 16 of the least significant 24 bits of the
public key modulus. However, [RFC4034] then goes on to incorrectly public key modulus. However, [RFC4034] then goes on to incorrectly
say that this is 4th to last and 3rd to last octets of the public key say that this is 4th to last and 3rd to last octets of the public key
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modulus. It is, in fact, the 3rd to last and 2nd to last octets. modulus. It is, in fact, the 3rd to last and 2nd to last octets.
4.6. Setting the DO Bit on Replies 5.6. Setting the DO Bit on Replies
As stated in [RFC3225], the DO bit of the query MUST be copied in the As stated in [RFC3225], the DO bit of the query MUST be copied in the
response. At least one implementation has done something different, response. At least one implementation has done something different,
so it may be wise for resolvers to be liberal in what they accept. so it may be wise for resolvers to be liberal in what they accept.
5.7. Setting the AD Bit on Queries
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4.7. Setting the AD Bit on Queries
The use of the AD bit in the query was previously undefined. This The use of the AD bit in the query was previously undefined. This
document defines it as a signal indicating that the requester document defines it as a signal indicating that the requester
@@ -401,7 +409,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
response. This allows a requestor to indicate that it understands response. This allows a requestor to indicate that it understands
the AD bit without also requesting DNSSEC data via the DO bit. the AD bit without also requesting DNSSEC data via the DO bit.
4.8. Setting the AD Bit on Replies 5.8. Setting the AD Bit on Replies
Section 3.2.3 of [RFC4035] describes under which conditions a Section 3.2.3 of [RFC4035] describes under which conditions a
validating resolver should set or clear the AD bit in a response. In validating resolver should set or clear the AD bit in a response. In
@@ -410,7 +418,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
conditions listed in RFC 4035, section 3.2.3, and the request conditions listed in RFC 4035, section 3.2.3, and the request
contained either a set DO bit or a set AD bit. contained either a set DO bit or a set AD bit.
4.9. Setting the CD bit on Requests 5.9. Handling Queries With the CD Bit Set
When processing a request with the CD bit set, a resolver SHOULD When processing a request with the CD bit set, a resolver SHOULD
attempt to return all responsive data, even data that has failed attempt to return all responsive data, even data that has failed
@@ -428,11 +436,20 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
up to five minutes.) In these cases, a new query with the CD bit set up to five minutes.) In these cases, a new query with the CD bit set
is required. is required.
For efficiency, a validator may wish to set the CD bit on all For efficiency, a validator SHOULD set the CD bit on upstream queries
upstream queries when it has a trust anchor at or above the QNAME when it has a trust anchor at or above the QNAME (and thus can
(and thus can reasonably expect to be able to validate the response). reasonably expect to be able to validate the response).
4.10. Nested Trust Anchors
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5.10. Nested Trust Anchors
A DNSSEC validator may be configured such that, for a given response, A DNSSEC validator may be configured such that, for a given response,
more than one trust anchor could be used to validate the chain of more than one trust anchor could be used to validate the chain of
@@ -441,24 +458,16 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
When the validator is asked to validate a response to When the validator is asked to validate a response to
"www.sub.zone.example.", either trust anchor could apply. "www.sub.zone.example.", either trust anchor could apply.
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When presented with this situation, DNSSEC validators have a choice When presented with this situation, DNSSEC validators have a choice
of which trust anchor(s) to use. Which to use is a matter of of which trust anchor(s) to use. Which to use is a matter of
implementation choice. It is possible and perhaps advisable to implementation choice. It is possible and perhaps advisable to
expose the choice of policy as a configuration option. The rest of expose the choice of policy as a configuration option. The rest of
this section discusses some possible policies. As a default, we this section discusses some possible policies. As a default, we
suggest that validators implement the "Accept Any Success" policy suggest that validators implement the "Accept Any Success" policy
described below in Section 4.10.2 while exposing other policies as described below in Section 5.10.2 while exposing other policies as
configuration options. configuration options.
4.10.1. Closest Encloser 5.10.1. Closest Encloser
One policy is to choose the trust anchor closest to the QNAME of the One policy is to choose the trust anchor closest to the QNAME of the
response. In our example, that would be the "zone.example." trust response. In our example, that would be the "zone.example." trust
@@ -480,7 +489,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
trust anchor. With the "closest encloser" policy, the validator gets trust anchor. With the "closest encloser" policy, the validator gets
validation failures. validation failures.
4.10.2. Accept Any Success 5.10.2. Accept Any Success
Another policy is to try all applicable trust anchors until one gives Another policy is to try all applicable trust anchors until one gives
a validation result of Secure, in which case the final validation a validation result of Secure, in which case the final validation
@@ -489,6 +498,13 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
or more trust anchors lead to a Bogus result and there is no Secure or more trust anchors lead to a Bogus result and there is no Secure
result, then the final validation result is Bogus. result, then the final validation result is Bogus.
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This has the advantage of causing the fewer validation failures, This has the advantage of causing the fewer validation failures,
which may deliver a better user experience. If one trust anchor is which may deliver a better user experience. If one trust anchor is
out of date (as in our above example), the user may still be able to out of date (as in our above example), the user may still be able to
@@ -497,17 +513,9 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
This policy has the disadvantage of making the validator subject to This policy has the disadvantage of making the validator subject to
compromise of the weakest of these trust anchors while making its compromise of the weakest of these trust anchors while making its
relatively painless to keep old trust anchors configured in relatively painless to keep old trust anchors configured in
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perpetuity. perpetuity.
4.10.3. Preference Based on Source 5.10.3. Preference Based on Source
When the trust anchors have come from different sources (e.g. When the trust anchors have come from different sources (e.g.
automated updates ([RFC5011]), one or more DLV registries automated updates ([RFC5011]), one or more DLV registries
@@ -532,9 +540,9 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
configured trust anchors. configured trust anchors.
5. Minor Corrections and Clarifications 6. Minor Corrections and Clarifications
5.1. Finding Zone Cuts 6.1. Finding Zone Cuts
Appendix C.8 of [RFC4035] discusses sending DS queries to the servers Appendix C.8 of [RFC4035] discusses sending DS queries to the servers
for a parent zone. To do that, a resolver may first need to apply for a parent zone. To do that, a resolver may first need to apply
@@ -545,22 +553,22 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
and in some situations the resolver may also need to apply special and in some situations the resolver may also need to apply special
rules to locate the name servers for the parent zone if the resolver rules to locate the name servers for the parent zone if the resolver
does not already have the parent's NS RRset. Section 4.2 of does not already have the parent's NS RRset. Section 4.2 of
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[RFC4035] specifies a mechanism for doing that. [RFC4035] specifies a mechanism for doing that.
5.2. Clarifications on DNSKEY Usage 6.2. Clarifications on DNSKEY Usage
Questions of the form "can I use a different DNSKEY for signing this Questions of the form "can I use a different DNSKEY for signing this
RRset" have occasionally arisen. RRset" have occasionally arisen.
The short answer is "yes, absolutely". You can even use a different The short answer is "yes, absolutely". You can even use a different
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DNSKEY for each RRset in a zone, subject only to practical limits on DNSKEY for each RRset in a zone, subject only to practical limits on
the size of the DNSKEY RRset. However, be aware that there is no way the size of the DNSKEY RRset. However, be aware that there is no way
to tell resolvers what a particularly DNSKEY is supposed to be used to tell resolvers what a particularly DNSKEY is supposed to be used
@@ -579,7 +587,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
possible to use a single DNSKEY, with or without the SEP bit set, to possible to use a single DNSKEY, with or without the SEP bit set, to
sign the entire zone, including the DNSKEY RRset itself. sign the entire zone, including the DNSKEY RRset itself.
5.3. Errors in Examples 6.3. Errors in Examples
The text in [RFC4035] Section C.1 refers to the examples in B.1 as The text in [RFC4035] Section C.1 refers to the examples in B.1 as
"x.w.example.com" while B.1 uses "x.w.example". This is painfully "x.w.example.com" while B.1 uses "x.w.example". This is painfully
@@ -594,12 +602,21 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
the reference to "a.z.w.w.example" should instead be "a.z.w.example", the reference to "a.z.w.w.example" should instead be "a.z.w.example",
as in the previous line. as in the previous line.
5.4. Errors in RFC 5155 6.4. Errors in RFC 5155
A NSEC3 record that matches an Empty Non-Terminal effectively has no A NSEC3 record that matches an Empty Non-Terminal effectively has no
type associated with it. This NSEC3 record has an empty type bit type associated with it. This NSEC3 record has an empty type bit
map. Section 3.2.1 of [RFC5155] contains the statement: map. Section 3.2.1 of [RFC5155] contains the statement:
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Blocks with no types present MUST NOT be included. Blocks with no types present MUST NOT be included.
However, the same section contains a regular expression: However, the same section contains a regular expression:
@@ -609,41 +626,33 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
The plus sign in the regular expression indicates that there is one The plus sign in the regular expression indicates that there is one
or more of the preceding element. This means that there must be at or more of the preceding element. This means that there must be at
least one window block. If this window block has no types, it least one window block. If this window block has no types, it
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contradicts with the first statement. Therefore, the correct text in contradicts with the first statement. Therefore, the correct text in
RFC 5155 3.2.1 should be: RFC 5155 3.2.1 should be:
Type Bit Maps Field = ( Window Block # | Bitmap Length | Bitmap )* Type Bit Maps Field = ( Window Block # | Bitmap Length | Bitmap )*
6. IANA Considerations 7. IANA Considerations
This document specifies no IANA Actions. This document specifies no IANA Actions.
7. Security Considerations 8. Security Considerations
This document adds two cryptographic features to the core DNSSEC This document adds two cryptographic features to the core DNSSEC
protocol. Additionally, it addresses some ambiguities and omissions protocol. Additionally, it addresses some ambiguities and omissions
in the core DNSSEC documents that, if not recognized and addressed in in the core DNSSEC documents that, if not recognized and addressed in
implementations, could lead to security failures. In particular, the implementations, could lead to security failures. In particular, the
validation algorithm clarifications in Section 3 are critical for validation algorithm clarifications in Section 4 are critical for
preserving the security properties DNSSEC offers. Furthermore, preserving the security properties DNSSEC offers. Furthermore,
failure to address some of the interoperability concerns in Section 4 failure to address some of the interoperability concerns in Section 5
could limit the ability to later change or expand DNSSEC, including could limit the ability to later change or expand DNSSEC, including
adding new algorithms. adding new algorithms.
8. References 9. References
8.1. Normative References 9.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987. STD 13, RFC 1034, November 1987.
@@ -656,6 +665,14 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements", Rose, "DNS Security Introduction and Requirements",
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RFC 4033, March 2005. RFC 4033, March 2005.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
@@ -666,13 +683,6 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
Rose, "Protocol Modifications for the DNS Security Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, March 2005. Extensions", RFC 4035, March 2005.
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[RFC4509] Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer [RFC4509] Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer
(DS) Resource Records (RRs)", RFC 4509, May 2006. (DS) Resource Records (RRs)", RFC 4509, May 2006.
@@ -684,7 +694,7 @@ Internet-Draft DNSSECbis Implementation Notes March 2010
and RRSIG Resource Records for DNSSEC", RFC 5702, and RRSIG Resource Records for DNSSEC", RFC 5702,
October 2009. October 2009.
8.2. Informative References 9.2. Informative References
[RFC3755] Weiler, S., "Legacy Resolver Compatibility for Delegation [RFC3755] Weiler, S., "Legacy Resolver Compatibility for Delegation
Signer (DS)", RFC 3755, May 2004. Signer (DS)", RFC 3755, May 2004.
@@ -711,32 +721,33 @@ Appendix A. Acknowledgments
finding errors and omissions in the DNSSECbis document set, have finding errors and omissions in the DNSSECbis document set, have
provided text suitable for inclusion in this document. provided text suitable for inclusion in this document.
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The lack of specificity about handling private algorithms, as The lack of specificity about handling private algorithms, as
described in Section 4.3, and the lack of specificity in handling ANY described in Section 5.3, and the lack of specificity in handling ANY
queries, as described in Section 3.2, were discovered by David queries, as described in Section 4.2, were discovered by David
Blacka. Blacka.
The error in algorithm 1 key tag calculation, as described in The error in algorithm 1 key tag calculation, as described in
Section 4.5, was found by Abhijit Hayatnagarkar. Donald Eastlake Section 5.5, was found by Abhijit Hayatnagarkar. Donald Eastlake
contributed text for Section 4.5. contributed text for Section 5.5.
The bug relating to delegation NSEC RR's in Section 3.1 was found by
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The bug relating to delegation NSEC RR's in Section 4.1 was found by
Roy Badami. Roy Arends found the related problem with DNAME. Roy Badami. Roy Arends found the related problem with DNAME.
The errors in the [RFC4035] examples were found by Roy Arends, who The errors in the [RFC4035] examples were found by Roy Arends, who
also contributed text for Section 5.3 of this document. also contributed text for Section 6.3 of this document.
The editors would like to thank Alfred Hoenes, Ed Lewis, Danny Mayer, The editors would like to thank Alfred Hoenes, Ed Lewis, Danny Mayer,
Olafur Gudmundsson, Suzanne Woolf, and Scott Rose for their Olafur Gudmundsson, Suzanne Woolf, Rickard Bellgrim, Mike St. Johns,
substantive comments on the text of this document. and Scott Rose for their substantive comments on the text of this
document.
Authors' Addresses Authors' Addresses
@@ -769,17 +780,6 @@ Authors' Addresses
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