draft-ietf-dnsext-dnssec-algo-signal-02.txt   draft-ietf-dnsext-dnssec-algo-signal-03.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: January 7, 2012 NIST Expires: July 6, 2012 NIST
July 6, 2011 January 3, 2012
Signaling Cryptographic Algorithm Understanding in DNSSEC Signaling Cryptographic Algorithm Understanding in DNSSEC
draft-ietf-dnsext-dnssec-algo-signal-02 draft-ietf-dnsext-dnssec-algo-signal-03
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 validating end-system resolvers to signal to a server which
cryptographic algorithms they support. cryptographic algorithms they support.
skipping to change at page 1, line 42 skipping to change at page 1, line 42
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on January 7, 2012. This Internet-Draft will expire on July 6, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 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.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Signaling DNSSEC Algorithm Understood (DAU) Using EDNS . . . . 3 2. Signaling DNSSEC Algorithm Understood (DAU) Using EDNS . . . . 3
3. Client Considerations . . . . . . . . . . . . . . . . . . . . . 4 3. Client Considerations . . . . . . . . . . . . . . . . . . . . . 4
3.1. Stub Resolvers . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Stub Resolvers . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Validating Stub Resolvers . . . . . . . . . . . . . . . . . 5 3.2. Validating Stub Resolvers . . . . . . . . . . . . . . . . . 5
3.3. Non-Validating Stub Resolvers . . . . . . . . . . . . . . . 5 3.3. Non-Validating Stub Resolvers . . . . . . . . . . . . . . . 5
3.4. Recursive Resolvers . . . . . . . . . . . . . . . . . . . . 5 3.4. Recursive Resolvers . . . . . . . . . . . . . . . . . . . . 5
3.4.1. Validating Recursive Resolvers . . . . . . . . . . . . 5 3.4.1. Validating Recursive Resolvers . . . . . . . . . . . . 5
3.4.2. Non-validating Recursive Resolvers . . . . . . . . . . 6 3.4.2. Non-validating Recursive Resolvers . . . . . . . . . . 5
4. Intermediate System Considerations . . . . . . . . . . . . . . 6 4. Intermediate System Considerations . . . . . . . . . . . . . . 6
5. Server Considerations . . . . . . . . . . . . . . . . . . . . . 6 5. Server Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Traffic Analysis Considerations . . . . . . . . . . . . . . . . 6 6. Traffic Analysis Considerations . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
9. Normative References . . . . . . . . . . . . . . . . . . . . . 7 9. Normative References . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
The DNS Security Extensions (DNSSEC) [RFC4033], [RFC4034] and The DNS Security Extensions (DNSSEC) [RFC4033], [RFC4034] and
[RFC4035] were developed to provide origin authentication and [RFC4035] were developed to provide origin authentication and
integrity protection for DNS data by using digital signatures. Each integrity protection for DNS data by using digital signatures. Each
digital signature RR (RRSIG) contains an algorithm code number. digital signature RR (RRSIG) contains an algorithm code number.
These algorithm codes tells validators which cryptographic algorithm These algorithm codes tells validators which cryptographic algorithm
was used to generate the digital signature. Authentication across was used to generate the digital signature.
delegation boundaries is maintained by storing a hash of a subzone's
key in the parent zone stored in a Delegation Signer (DS) RR. These
DS RR's contain a second code number to identify the hash algorithm
used to construct the DS RR.
This draft sets out to specify a way for validating end-system This draft sets out to specify a way for validating end-system
resolvers to tell a server which cryptographic and/or hash algorithms resolvers to tell a server which cryptographic algorithms they
they support in a DNS query. This is done using the EDNS attribute support in a DNS query. This is done using the EDNS attribute values
values in the OPT meta-RR [RFC2671]. in the OPT meta-RR [RFC2671].
This proposed EDNS option serves to measure the acceptance and use of This proposed EDNS option serves to measure the acceptance and use of
new digital signing and hash algorithms. This algorithm signaling new digital signing algorithms. This algorithm signaling option can
option can be used by zone administrators as a gauge to measure the be used by zone administrators as a gauge to measure the successful
successful deployment of code that implements a newly deployed deployment of code that implements a newly deployed digital signature
digital signature or hash algorithm used with DNSSEC. A zone algorithm used with DNSSEC. A zone administrator may be able to
administrator may be able to determine when to stop serving the old determine when to stop serving the old algorithm when the server sees
algorithm when the server sees that a significant number of its that a significant number of its clients signal that they are able to
clients signal that they are able to accept the new algorithm. Note accept the new algorithm. Note that this survey may be conducted
that this survey may be conducted over the period of years before a over the period of years before a tipping point is seen.
tipping point is seen.
This draft does not seek to include another process for including new This draft does not seek to include another process for including new
algorithms for use with DNSSEC (see . It also does not address the algorithms for use with DNSSEC (see . It also does not address the
question of which algorithms are to be included in any official list question of which algorithms are to be included in any official list
of mandatory or recommended cryptographic algorithms for use with of mandatory or recommended cryptographic algorithms for use with
DNSSEC. Rather, this document specifies a means by which a client DNSSEC. Rather, this document specifies a means by which a client
query can signal a set of algorithms it implements. query can signal a set of algorithms it implements.
2. Signaling DNSSEC Algorithm Understood (DAU) Using EDNS 2. Signaling DNSSEC Algorithm Understood (DAU) Using EDNS
The ENDS0 specification outlined in [RFC2671] defines a way to The ENDS0 specification outlined in [RFC2671] defines a way to
include new options using a standardized mechanism. These options include new options using a standardized mechanism. These options
are contained in the RDATA of the OPT meta-RR. This document defines are contained in the RDATA of the OPT meta-RR. This document defines
a new EDNS0 option for a client to signal which algorithms the client a new EDNS0 option for a client to signal which algorithms the client
supports. supports.
The figure below shows how the signaling attribute is defined in the The figure below shows how the digital signature signaling attribute
RDATA of the OPT RR specified in [RFC2671]: is defined in the RDATA of the OPT RR specified in [RFC2671]:
0 8 16 0 8 16
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| OPTION-CODE (TBD) | | OPTION-CODE (TBD) |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| DIGITAL-SIG-LIST-LENGTH | | DIGITAL-SIG-LIST-LENGTH |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ALG-CODE | ... \ | ALG-CODE | ... \
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| DS-HASH-LIST-LENGTH |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| HASH-CODE | ... \
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
OPTION-CODE is the code for the DNSSEC Algorithm Understood (DAU) OPTION-CODE is the code for the DNSSEC Algorithm Understood (DAU)
option. Its value is fixed at TBD. option. Its value is fixed at TBD.
DIGITAL-SIG-LIST-LENGTH is the length of the list of digital DIGITAL-SIG-LIST-LENGTH is the length of the list of digital
signature algorithms in octets. DNSSEC algorithm codes are 1 octet signature algorithms in octets. DNSSEC algorithm codes are 1 octet
long so this value is the number of octets. long so this value is the number of octets.
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 that the client indicates as understood. The values algorithms that the client indicates as understood. The values
SHOULD be in descending order of preference, with the most preferred SHOULD be in descending order of preference, with the most preferred
algorithm first. For example, if a validating client implements RSA/ algorithm first. For example, if a validating client implements RSA/
SHA-1, RSA/SHA-256 and prefers the latter, the value of ALG-CODE SHA-1, RSA/SHA-256 and prefers the latter, the value of ALG-CODE
would be: 8 (RSA/SHA-256), 5 (RSA/SHA-1). would be: 8 (RSA/SHA-256), 5 (RSA/SHA-1).
DS-HASH-LIST-LENGTH is the length of the list of hash algorithms in
octets. DNSSEC DS hash codes are 1 octet long so this value is the
number of octets.
HASH-CODE is the list of assigned values of DNSSEC DS hash algorithms
that the client indicates as understood. Like the ALG-CODE above,
the values SHOULD be in descending order of preference, with the most
preferred algorithm first.
3. Client Considerations 3. Client Considerations
A validating end-system resolver sets the DAU option in the OPT A validating end-system resolver sets the DAU option in the OPT
meta-RR when sending a query. The validating end-system resolver meta-RR when sending a query. The validating end-system resolver
sets the value(s) in the order of preference, with the most preferred sets the value(s) in the order of preference, with the most preferred
algorithm(s) first as described in section 2. The end-system algorithm(s) first as described in section 2. The end-system
resolver SHOULD also set the DNSSEC-OK bit [RFC4035] to indicate that resolver SHOULD also set the DNSSEC-OK bit [RFC4035] to indicate that
it wishes to receive DNSSEC RRs in the response. it wishes to receive DNSSEC RRs in the response.
Note that the PRIVATEDNS (253) and/or the PRIVATEOID (254) codes Note that the PRIVATEDNS (253) and/or the PRIVATEOID (254) codes
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