draft-ietf-dnsext-dnssec-bis-updates-07.txt   draft-ietf-dnsext-dnssec-bis-updates-08.txt 
Network Working Group S. Weiler Network Working Group S. Weiler
Internet-Draft SPARTA, Inc. Internet-Draft SPARTA, Inc.
Updates: 4034, 4035 D. Blacka Updates: 4033, 4034, 4035, 5155 D. Blacka
(if approved) VeriSign, Inc. (if approved) VeriSign, Inc.
Expires: January 15, 2009 July 14, 2008 Intended status: Standards Track January 14, 2009
Expires: July 18, 2009
Clarifications and Implementation Notes for DNSSECbis Clarifications and Implementation Notes for DNSSECbis
draft-ietf-dnsext-dnssec-bis-updates-07 draft-ietf-dnsext-dnssec-bis-updates-08
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Abstract Abstract
This document is a collection of minor technical clarifications to This document is a collection of technical clarifications to the
the DNSSECbis document set. It is meant to serve as a resource to DNSSECbis document set. It is meant to serve as a resource to
implementors as well as an interim repository of DNSSECbis errata. implementors as well as a repository of DNSSECbis errata.
Table of Contents Table of Contents
1. Introduction and Terminology . . . . . . . . . . . . . . . . . 3 1. Introduction and Terminology . . . . . . . . . . . . . . . . . 3
1.1. Structure of this Document . . . . . . . . . . . . . . . . 3 1.1. Structure of this Document . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Significant Concerns . . . . . . . . . . . . . . . . . . . . . 3 2. Important Additions to DNSSSECbis . . . . . . . . . . . . . . 3
2.1. Clarifications on Non-Existence Proofs . . . . . . . . . . 3 2.1. NSEC3 Support . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Validating Responses to an ANY Query . . . . . . . . . . . 4 2.2. SHA-256 Support . . . . . . . . . . . . . . . . . . . . . 3
2.3. Check for CNAME . . . . . . . . . . . . . . . . . . . . . 4 3. Significant Concerns . . . . . . . . . . . . . . . . . . . . . 4
2.4. Unsecure Delegation Proofs . . . . . . . . . . . . . . . . 4 3.1. Clarifications on Non-Existence Proofs . . . . . . . . . . 4
2.5. Errors in Canonical Form Type Code List . . . . . . . . . 4 3.2. Validating Responses to an ANY Query . . . . . . . . . . . 4
3. Interoperability Concerns . . . . . . . . . . . . . . . . . . 5 3.3. Check for CNAME . . . . . . . . . . . . . . . . . . . . . 5
3.1. Unknown DS Message Digest Algorithms . . . . . . . . . . . 5 3.4. Insecure Delegation Proofs . . . . . . . . . . . . . . . . 5
3.2. Private Algorithms . . . . . . . . . . . . . . . . . . . . 5 3.5. Errors in Canonical Form Type Code List . . . . . . . . . 5
3.3. Caution About Local Policy and Multiple RRSIGs . . . . . . 6 4. Interoperability Concerns . . . . . . . . . . . . . . . . . . 5
3.4. Key Tag Calculation . . . . . . . . . . . . . . . . . . . 6 4.1. Unknown DS Message Digest Algorithms . . . . . . . . . . . 5
3.5. Setting the DO Bit on Replies . . . . . . . . . . . . . . 6 4.2. Private Algorithms . . . . . . . . . . . . . . . . . . . . 6
4. Minor Corrections and Clarifications . . . . . . . . . . . . . 7 4.3. Caution About Local Policy and Multiple RRSIGs . . . . . . 6
4.1. Finding Zone Cuts . . . . . . . . . . . . . . . . . . . . 7 4.4. Key Tag Calculation . . . . . . . . . . . . . . . . . . . 7
4.2. Clarifications on DNSKEY Usage . . . . . . . . . . . . . . 7 4.5. Setting the DO Bit on Replies . . . . . . . . . . . . . . 7
4.3. Errors in Examples . . . . . . . . . . . . . . . . . . . . 7 4.6. Setting the AD bit on Replies . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4.7. Setting the CD bit on Requests . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 4.8. Nested Trust Anchors . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Minor Corrections and Clarifications . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . . 8 5.1. Finding Zone Cuts . . . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . . 9 5.2. Clarifications on DNSKEY Usage . . . . . . . . . . . . . . 8
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 9 5.3. Errors in Examples . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 5.4. Errors in RFC 5155 . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . . 11
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction and Terminology 1. Introduction and Terminology
This document lists some minor clarifications and corrections to This document lists some clarifications and corrections to DNSSECbis,
DNSSECbis, as described in [RFC4033], [RFC4034], and [RFC4035]. as described in [RFC4033], [RFC4034], and [RFC4035].
It is intended to serve as a resource for implementors and as a It is intended to serve as a resource for implementors and as a
repository of items that need to be addressed when advancing the repository of items that need to be addressed when advancing the
DNSSECbis documents from Proposed Standard to Draft Standard. DNSSECbis documents from Proposed Standard to Draft Standard.
Proposed substantive additions to this document should be sent to the
namedroppers mailing list as well as to the editors of this document.
The editors would greatly prefer contributions of text suitable for
direct inclusion in this document.
1.1. Structure of this Document 1.1. Structure of this Document
The clarifications to DNSSECbis are sorted according to the editors' The clarifications to DNSSECbis are sorted according to their
impression of their importance, starting with ones which could, if importance, starting with ones which could, if ignored, lead to
ignored, lead to security and stability problems and progressing down security and stability problems and progressing down to
to clarifications that are likely to have little operational impact. clarifications that are expected to have little operational impact.
1.2. Terminology 1.2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Significant Concerns 2. Important Additions to DNSSSECbis
This section provides
2.1. NSEC3 Support
[RFC5155] describes the use and behavior of the NSEC3 and NSEC3PARAM
records for hashed denial of existence. Validator implementations
are strongly encouraged to include support for NSEC3 as a number of
highly visible zones are expected to use it. Validators that do not
support validation of responses using NSEC3 will likely be hampered
in validating large portions of the DNS space.
[RFC5155] should be considered part of the DNS Security Document
Family as described by [RFC4033], Section 10.
2.2. SHA-256 Support
[RFC4509] describes the use of SHA-256 as a digest algorithm for use
with Delegation Signer (DS) RRs. [I-D.ietf-dnsext-dnssec-rsasha256]
describes the use of the RSASHA256 algorthim for use in DNSKEY and
RRSIG RRs. Validator implementations are strongly encouraged to
include support for this algorithm for DS, DNSKEY, and RRSIG records.
Both [RFC4509] and [I-D.ietf-dnsext-dnssec-rsasha256] should also be
considered part of the DNS Security Document Family as described by
[RFC4033], Section 10.
3. Significant Concerns
This section provides clarifications that, if overlooked, could lead This section provides clarifications that, if overlooked, could lead
to security issues or major interoperability problems. to security issues or major interoperability problems.
2.1. Clarifications on Non-Existence Proofs 3.1. Clarifications on Non-Existence Proofs
[RFC4035] Section 5.4 slightly underspecifies the algorithm for [RFC4035] Section 5.4 underspecifies the algorithm for checking non-
checking non-existence proofs. In particular, the algorithm there existence proofs. In particular, the algorithm as presented would
might incorrectly allow the NSEC from an ancestor zone to prove the incorrectly allow an NSEC or NSEC3 RR from an ancestor zone to prove
non-existence of other RRs at that name in the child zone or other the non-existence of other RRs at that name in the child zone or
names in the child zone. It might also allow a NSEC at the same name other names in the child zone.
as a DNAME to prove the non-existence of names beneath that DNAME.
An ancestor delegation NSEC (one with the NS bit set, but no SOA bit An "ancestor delegation" NSEC RR (or NSEC3 RR) is one with:
set, and with a signer field that's shorter than the owner name) MUST
NOT be used to assume non-existence of any RRs below that zone cut
(both RRs at that ownername and at ownernames with more leading
labels, no matter their content). Similarly, an NSEC with the DNAME
bit set must not be used to assume the non-existence of any subdomain
of that NSEC's owner name.
2.2. Validating Responses to an ANY Query o the NS bit set,
o the SOA bit clear, and
o a signer field that is shorter than the owner name of the NSEC RR,
or the original owner name for the NSEC3 RR.
Ancestor delegation NSEC or NSEC3 RRs MUST NOT be used to assume non-
existence of any RRs below that zone cut, which include all RRs at
that (original) owner name other than DS RRs, and all RRs below that
owner name regardless of type.
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
name as a DNAME, to prove the non-existence of names beneath that
DNAME. An NSEC or NSEC3 RR with the DNAME bit set MUST NOT be used
to assume the non-existence of any subdomain of that NSEC/NSEC3 RR's
(original) owner name.
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
QTYPE=* may include a subset of the RRsets at a given name -- it is QTYPE=* may include a subset of the RRsets at a given name -- it is
not necessary to include all RRsets at the QNAME in the response. not necessary to include all RRsets at the QNAME in the response.
When validating a response to QTYPE=*, validate all received RRsets When validating a response to QTYPE=*, validate all received RRsets
that match QNAME and QCLASS. If any of those RRsets fail validation, that match QNAME and QCLASS. If any of those RRsets fail validation,
treat the answer as Bogus. If there are no RRsets matching QNAME and treat the answer as Bogus. If there are no RRsets matching QNAME and
QCLASS, validate that fact using the rules in [RFC4035] Section 5.4 QCLASS, validate that fact using the rules in [RFC4035] Section 5.4
(as clarified in this document). To be clear, a validator must not (as clarified in this document). To be clear, a validator must not
expect to receive all records at the QNAME in response to QTYPE=*. expect to receive all records at the QNAME in response to QTYPE=*.
2.3. Check for CNAME 3.3. 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 NODATA on (or that should be based on) CNAMEs. When validating a NOERROR/
response, it's important to check the CNAME bit in the NSEC bitmap. NODATA response, validators MUST check the CNAME bit in the matching
If the CNAME bit is set, the validator MUST validate the CNAME RR and NSEC or NSEC3 RR's type bitmap. If the CNAME bit is set, the
follow it, as appropriate. validator MUST validate the CNAME RR and follow it, as appropriate.
2.4. Unsecure Delegation Proofs 3.4. 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 unsecure, needs to check for the absence of the DS and delegation is not secure, needs to check for the absence of the DS
SOA bits in the NSEC type bitmap. The validator also needs to check and SOA bits in the NSEC (or NSEC3) type bitmap. The validator also
for the presence of the NS bit in the NSEC RR (proving that there is, needs to check for the presence of the NS bit in the NSEC (or NSEC3)
indeed, a delegation). If this is not checked, spoofed unsigned RR (proving that there is, indeed, a delegation). If this is not
delegations might be used to claim that an existing signed record is checked, spoofed unsigned delegations might be used to claim that an
not signed. existing signed record is not signed.
2.5. Errors in Canonical Form Type Code List 3.5. 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.
[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
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.
The same section also lists HINFO twice. The implementor is The same section also erroneously lists HINFO, and twice at that.
encouraged to exercise good discretion and professional judgment when Since HINFO records contain no domain names, they are not subject to
deciding whether to downcase such DNS names once or twice. [RFC3597] downcasing.
contained the same error and, since it predated RFC3755, it doesn't
mention RRSIG or NSEC.
3. Interoperability Concerns 4. Interoperability Concerns
3.1. Unknown DS Message Digest Algorithms 4.1. 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 algorithms, as to zones that are signed with entirely unsupported algorithms, as
indicated by the algorithms shown in those zone's DS RRsets. It does indicated by the algorithms shown in those zone's DS RRsets. It does
not explicitly address how to handle DS records that use unsupported not explicitly address how to handle DS records that use unsupported
message digest algorithms. In brief, DS records using unknown or message digest algorithms. In brief, DS records using unknown or
unsupported message digest algorithms MUST be treated the same way as unsupported message digest algorithms MUST be treated the same way as
DS records referring to DNSKEY RRs of unknown or unsupported DS records referring to DNSKEY RRs of unknown or unsupported
algorithms. algorithms.
skipping to change at page 5, line 38 skipping to change at page 6, line 23
To paraphrase the above, when determining the security status of a To paraphrase the above, when determining the security status of a
zone, a validator discards (for this purpose only) any DS records zone, a validator discards (for this purpose only) any DS records
listing unknown or unsupported algorithms. If none are left, the listing unknown or unsupported algorithms. If none are left, the
zone is treated as if it were unsigned. zone is treated as if it were unsigned.
Modified to consider DS message digest algorithms, a validator also Modified to consider DS message digest algorithms, a validator also
discards any DS records using unknown or unsupported message digest discards any DS records using unknown or unsupported message digest
algorithms. algorithms.
3.2. Private Algorithms 4.2. 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
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
algorithm(s) is actually in use. algorithm(s) is actually in use.
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
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 3.1). In these cases, the functions, as discussed in Section 4.1). 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
hash of the DNSKEY RR's owner name and RDATA matches the digest in hash of the DNSKEY RR's owner name and RDATA matches the digest in
the DS RR. If they do not match, and no other DS establishes that the DS RR. If they do not match, and no other DS establishes that
the zone is secure, the referral should be considered BAD data, as the zone is secure, the referral should be considered BAD data, as
discussed in [RFC4035]. discussed in [RFC4035].
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].
3.3. Caution About Local Policy and Multiple RRSIGs 4.3. 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
the resolver also has to test these RRSIG RRs and how to resolve the resolver also has to test these RRSIG RRs and how to resolve
conflicts if these RRSIG RRs lead to differing results." In most conflicts if these RRSIG RRs lead to differing results." In most
cases, a resolver would be well advised to accept any valid RRSIG as cases, a resolver would be well advised to accept any valid RRSIG as
sufficient. If the first RRSIG tested fails validation, a resolver sufficient. If the first RRSIG tested fails validation, a resolver
would be well advised to try others, giving a successful validation would be well advised to try others, giving a successful validation
result if any can be validated and giving a failure only if all result if any can be validated and giving a failure only if all
RRSIGs fail validation. RRSIGs fail validation.
If a resolver adopts a more restrictive policy, there's a danger that If a resolver adopts a more restrictive policy, there's a danger that
properly-signed data might unnecessarily fail validation, perhaps properly-signed data might unnecessarily fail validation, perhaps
because of cache timing issues. Furthermore, certain zone management because of cache timing issues. Furthermore, certain zone management
techniques, like the Double Signature Zone-signing Key Rollover techniques, like the Double Signature Zone-signing Key Rollover
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.
3.4. Key Tag Calculation 4.4. 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
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.
3.5. Setting the DO Bit on Replies 4.5. Setting the DO Bit on Replies
[RFC4035] does not provide any instructions to servers as to how to [RFC4035] does not provide any instructions to servers as to how to
set the DO bit. Some authoritative server implementations have set the DO bit. Some authoritative server implementations have
chosen to copy the DO bit settings from the incoming query to the chosen to copy the DO bit settings from the incoming query to the
outgoing response. Others have chosen to never set the DO bit in outgoing response. Others have chosen to never set the DO bit in
responses. Either behavior is permitted. To be clear, in replies to responses. Either behavior is permitted. To be clear, in replies to
queries with the DO-bit set servers may or may not set the DO bit. queries with the DO-bit set servers may or may not set the DO bit.
4. Minor Corrections and Clarifications 4.6. Setting the AD bit on Replies
4.1. Finding Zone Cuts Section 3.2.3 of [RFC4035] describes under which conditions a
validating resolver should set or clear the AD bit in a response. In
order to protect legacy stub resolvers and middleboxes, validating
resolvers SHOULD only set the AD bit when a response both meets the
conditions listed in RFC 4035, section 3.2.3, and the request
contained either a set DO bit or a set AD bit.
Note that the use of the AD bit in the query was previously
undefined. This document defines it as a signal indicating that the
requester understands and is interested in the value of the AD bit in
the response. This allows a requestor to indicate that it
understands the AD bit without also requesting DNSSEC data via the DO
bit.
4.7. Setting the CD bit on Requests
When processing a request with the CD bit set, the resolver MUST set
the CD bit on its upstream queries.
4.8. Nested Trust Anchors
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
trust to the response zone. For example, imagine a validor
configured with trust anchors for "example." and "zone.example."
When the validator is asked to validate a response to
"www.sub.zone.example.", either trust anchor could apply.
When presented with this situation, DNSSEC validators SHOULD try all
applicable trust anchors until one succeeds.
There are some scenarios where different behaviors, such as choosing
the trust anchor closest to the QNAME of the response, may be
desired. A DNSSEC validator MAY enable such behaviors as
configurable overrides.
5. Minor Corrections and Clarifications
5.1. 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
special rules to discover what those servers are. special rules to discover what those servers are.
As explained in Section 3.1.4.1 of [RFC4035], security-aware name As explained in Section 3.1.4.1 of [RFC4035], security-aware name
servers need to apply special processing rules to handle the DS RR, servers need to apply special processing rules to handle the DS RR,
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
[RFC4035] specifies a mechanism for doing that. [RFC4035] specifies a mechanism for doing that.
4.2. Clarifications on DNSKEY Usage 5.2. 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
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
for -- any DNSKEY in the zone's signed DNSKEY RRset may be used to for -- any DNSKEY in the zone's signed DNSKEY RRset may be used to
authenticate any RRset in the zone. For example, if a weaker or less authenticate any RRset in the zone. For example, if a weaker or less
skipping to change at page 7, line 45 skipping to change at page 9, line 18
Furthermore, note that the SEP bit setting has no effect on how a Furthermore, note that the SEP bit setting has no effect on how a
DNSKEY may be used -- the validation process is specifically DNSKEY may be used -- the validation process is specifically
prohibited from using that bit by [RFC4034] section 2.1.2. It is prohibited from using that bit by [RFC4034] section 2.1.2. It is
possible to use a DNSKEY without the SEP bit set as the sole secure possible to use a DNSKEY without the SEP bit set as the sole secure
entry point to the zone, yet use a DNSKEY with the SEP bit set to entry point to the zone, yet use a DNSKEY with the SEP bit set to
sign all RRsets in the zone (other than the DNSKEY RRset). It's also sign all RRsets in the zone (other than the DNSKEY RRset). It's also
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.
4.3. Errors in Examples 5.3. 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
obvious in the second paragraph where it states that the RRSIG labels obvious in the second paragraph where it states that the RRSIG labels
field value of 3 indicates that the answer was not the result of field value of 3 indicates that the answer was not the result of
wildcard expansion. This is true for "x.w.example" but not for wildcard expansion. This is true for "x.w.example" but not for
"x.w.example.com", which of course has a label count of 4 "x.w.example.com", which of course has a label count of 4
(antithetically, a label count of 3 would imply the answer was the (antithetically, a label count of 3 would imply the answer was the
result of a wildcard expansion). result of a wildcard expansion).
The first paragraph of [RFC4035] Section C.6 also has a minor error: The first paragraph of [RFC4035] Section C.6 also has a minor error:
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. IANA Considerations 5.4. Errors in RFC 5155
A NSEC3 record, that matches an Empty Non-Terminal, effectively has
no type associated with it. This NSEC3 record has an empty type bit
map. Section 3.2.1 of [RFC5155] contains the statement:
Blocks with no types present MUST NOT be included.
However, the same section contains a regular expression:
Type Bit Maps Field = ( Window Block # | Bitmap Length | Bitmap )+
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
least one window block. If this window block has no types, it
contradicts with the first statement. Therefore, the correct text in
RFC 5155 3.2.1 should be:
Type Bit Maps Field = ( Window Block # | Bitmap Length | Bitmap )*
6. IANA Considerations
This document specifies no IANA Actions. This document specifies no IANA Actions.
6. Security Considerations 7. Security Considerations
This document does not make fundamental changes to the DNSSEC This document does not make fundamental changes to the DNSSEC
protocol, as it was generally understood when DNSSECbis was protocol, as it was generally understood when DNSSECbis was
published. It does, however, address some ambiguities and omissions published. It does, however, address some ambiguities and omissions
in those documents that, if not recognized and addressed in in those 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 2 are critical for validation algorithm clarifications in Section 3 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 3 failure to address some of the interoperability concerns in Section 4
could limit the ability to later change or expand DNSSEC, including could limit the ability to later change or expand DNSSEC, including
by adding new algorithms. by adding new algorithms.
7. References 8. References
7.1. Normative References 8.1. Normative References
[I-D.ietf-dnsext-dnssec-rsasha256]
Jansen, J., "Use of SHA-2 algorithms with RSA in DNSKEY
and RRSIG Resource Records for DNSSEC",
draft-ietf-dnsext-dnssec-rsasha256-10 (work in progress),
January 2009.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
RFC 1034, STD 13, November 1987. RFC 1034, STD 13, November 1987.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP 14, March 1997. Requirement Levels", RFC 2119, BCP 14, March 1997.
[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",
RFC 4033, March 2005. RFC 4033, March 2005.
skipping to change at page 9, line 4 skipping to change at page 10, line 49
[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",
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.
Rose, "Resource Records for the DNS Security Extensions", Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, March 2005. RFC 4034, March 2005.
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, March 2005. Extensions", RFC 4035, March 2005.
7.2. Informative References [RFC4509] Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer
(DS) Resource Records (RRs)", RFC 4509, May 2006.
[RFC3597] Gustafsson, A., "Handling of Unknown DNS Resource Record [RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
(RR) Types", RFC 3597, September 2003. Security (DNSSEC) Hashed Authenticated Denial of
Existence", RFC 5155, March 2008.
8.2. 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.
[RFC4641] Kolkman, O. and R. Gieben, "DNSSEC Operational Practices", [RFC4641] Kolkman, O. and R. Gieben, "DNSSEC Operational Practices",
RFC 4641, September 2006. RFC 4641, September 2006.
[RFC4955] Blacka, D., "DNS Security (DNSSEC) Experiments", RFC 4955, [RFC4955] Blacka, D., "DNS Security (DNSSEC) Experiments", RFC 4955,
July 2007. July 2007.
Appendix A. Acknowledgments Appendix A. Acknowledgments
The editors would like the thank Rob Austein for his previous work as The editors would like the thank Rob Austein for his previous work as
an editor of this document. an editor of this document.
The editors are extremely grateful to those who, in addition to The editors are extremely grateful to those who, in addition to
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.
The lack of specificity about handling private algorithms, as The lack of specificity about handling private algorithms, as
described in Section 3.2, and the lack of specificity in handling ANY described in Section 4.2, and the lack of specificity in handling ANY
queries, as described in Section 2.2, were discovered by David queries, as described in Section 3.2, 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 3.4, was found by Abhijit Hayatnagarkar. Donald Eastlake Section 4.4, was found by Abhijit Hayatnagarkar. Donald Eastlake
contributed text for Section 3.4. contributed text for Section 4.4.
The bug relating to delegation NSEC RR's in Section 2.1 was found by The bug relating to delegation NSEC RR's in Section 3.1 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 4.3 of this document. also contributed text for Section 5.3 of this document.
The editors would like to thank Ed Lewis, Danny Mayer, Olafur The editors would like to thank Ed Lewis, Danny Mayer, Olafur
Gudmundsson, Suzanne Woolf, and Scott Rose for their substantive Gudmundsson, Suzanne Woolf, and Scott Rose for their substantive
comments on the text of this document. comments on the text of this document.
Authors' Addresses Authors' Addresses
Samuel Weiler Samuel Weiler
SPARTA, Inc. SPARTA, Inc.
7110 Samuel Morse Drive 7110 Samuel Morse Drive
skipping to change at page 11, line 4 skipping to change at line 532
Email: weiler@tislabs.com Email: weiler@tislabs.com
David Blacka David Blacka
VeriSign, Inc. VeriSign, Inc.
21345 Ridgetop Circle 21345 Ridgetop Circle
Dulles, VA 20166 Dulles, VA 20166
US US
Email: davidb@verisign.com Email: davidb@verisign.com
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