draft-ietf-dnsext-dnssec-algo-signal-08.txt   draft-ietf-dnsext-dnssec-algo-signal-09.txt 
DNS Extensions Working Group S. Crocker DNS Extensions Working Group S. Crocker
Internet-Draft Shinkuro Inc. Internet-Draft Shinkuro Inc.
Intended status: Standards Track S. Rose Intended status: Standards Track S. Rose
Expires: February 15, 2013 NIST Expires: March 28, 2013 NIST
August 14, 2012 September 24, 2012
Signaling Cryptographic Algorithm Understanding in DNSSEC Signaling Cryptographic Algorithm Understanding in DNSSEC
draft-ietf-dnsext-dnssec-algo-signal-08 draft-ietf-dnsext-dnssec-algo-signal-09
Abstract Abstract
The DNS Security Extensions (DNSSEC) were developed to provide origin The DNS Security Extensions (DNSSEC) were developed to provide origin
authentication and integrity protection for DNS data by using digital authentication and integrity protection for DNS data by using digital
signatures. These digital signatures can be generated using signatures. These digital signatures can be generated using
different algorithms. This draft sets out to specify a way for different algorithms. This draft sets out to specify a way for
validating end-system resolvers to signal to a server which digital validating end-system resolvers to signal to a server which digital
signature and hash algorithms they support. signature and hash algorithms they support.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. 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."
This Internet-Draft will expire on February 15, 2013. This Internet-Draft will expire on March 28, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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
publication of this document. Please review these documents publication of this document. Please review these documents
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o NSEC3 Hash Understood (N3U) option for NSEC3 hash algorithms. Its o NSEC3 Hash Understood (N3U) option for NSEC3 hash algorithms. Its
value is fixed at TBD3. value is fixed at TBD3.
LIST-LENGTH is the length of the list of digital signature or hash LIST-LENGTH is the length of the list of digital signature or hash
algorithm codes in octets. Each algorithm code occupies a single algorithm codes in octets. Each algorithm code occupies a single
octet. octet.
ALG-CODE is the list of assigned values of DNSSEC zone signing ALG-CODE is the list of assigned values of DNSSEC zone signing
algorithms, DS hash algorithms, or NSEC3 hash algorithms (depending algorithms, DS hash algorithms, or NSEC3 hash algorithms (depending
on the OPTION-CODE in use) that the client declares to be supported. on the OPTION-CODE in use) that the client declares to be supported.
The order of the code values can be arbitrary and SHOULD NOT be used The order of the code values can be arbitrary and MUST NOT be used to
to infer preference. infer preference.
If all three options are included in the OPT RR, there is a potential If all three options are included in the OPT RR, there is a potential
for the OPT RR to take up considerable size in the DNS message. for the OPT RR to take up considerable size in the DNS message.
However, in practical terms, including all three options is likely to However, in practical terms, including all three options is likely to
take up 22-32 octets (average of 6-10 digital signature algorithms, take up 22-32 octets (average of 6-10 digital signature algorithms,
3-5 DS hash algorithms and 1-5 NSEC3 hash algorithms) including the 3-5 DS hash algorithms and 1-5 NSEC3 hash algorithms) including the
EDNS option codes and option lengths in a potential future example. EDNS option codes and option lengths in a potential future example.
3. Client Considerations 3. Client Considerations
A validating end-system resolver sets the DAU, DHU and/or N3U option, A validating end-system resolver sets the DAU, DHU and/or N3U option,
or combination thereof in the OPT meta-RR when sending a query. The or combination thereof in the OPT meta-RR when sending a query. The
validating end-system resolver sets the value(s) in any arbitrary validating end-system resolver MUST also set the DNSSEC-OK bit
order. The validating end-system resolver MUST also set the [RFC4035] to indicate that it wishes to receive DNSSEC RRs in the
DNSSEC-OK bit [RFC4035] to indicate that it wishes to receive DNSSEC response.
RRs in the response.
Note that the PRIVATEDNS (253) and/or the PRIVATEOID (254) digital Note that the PRIVATEDNS (253) and/or the PRIVATEOID (254) digital
signature codes both cover a potentially wide range of algorithms and signature codes both cover a potentially wide range of algorithms and
are likely not useful to a server. There is no compelling reason for are likely not useful to a server. There is no compelling reason for
a client to include these codes in its list of the DAU. Likewise, a client to include these codes in its list of the DAU. Likewise,
clients MUST NOT include RESERVED codes in any of the options. clients MUST NOT include RESERVED codes in any of the options.
3.1. Stub Resolvers 3.1. Stub Resolvers
Typically, stub resolvers rely on an upstream recursive server (or Typically, stub resolvers rely on an upstream recursive server (or
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3.1.1. Validating Stub Resolvers 3.1.1. Validating Stub Resolvers
A validating stub resolver already (usually) sets the DO bit A validating stub resolver already (usually) sets the DO bit
[RFC4035] to indicate that it wishes to receive additional DNSSEC RRs [RFC4035] to indicate that it wishes to receive additional DNSSEC RRs
(i.e. RRSIG RRs) in the response. Such validating resolvers SHOULD (i.e. RRSIG RRs) in the response. Such validating resolvers SHOULD
include the DAU, DHU and/or the N3U option(s) in the OPT RR when include the DAU, DHU and/or the N3U option(s) in the OPT RR when
sending a query. sending a query.
3.1.2. Non-Validating Stub Resolvers 3.1.2. Non-Validating Stub Resolvers
The DAU, DHU and N3U EDNS options are NOT RECOMMENDED for non- The DAU, DHU and N3U EDNS options MUST NOT be included by non-
validating stub resolvers. validating stub resolvers.
3.2. Recursive Resolvers 3.2. Recursive Resolvers
3.2.1. Validating Recursive Resolvers 3.2.1. Validating Recursive Resolvers
A validating recursive resolver sets the DAU, DHU and/or N3U A validating recursive resolver sets the DAU, DHU and/or N3U
option(s) when performing recursion based on its list of algorithms option(s) when performing recursion based on its list of algorithms
and any DAU, DHU and/or N3U option lists in the stub client query. and any DAU, DHU and/or N3U option lists in the stub client query.
When the recursive server receives a query with one or more of the When the recursive server receives a query with one or more of the
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