< draft-crocker-dnssec-algo-signal-06.txt		draft-crocker-dnssec-algo-signal-07.txt >
	DNS Extensions Working Group S. Crocker		DNS Extensions Working Group S. Crocker
	Internet-Draft Shinkuro Inc.		Internet-Draft Shinkuro Inc.
	Updates: 4035 (if approved) S. Rose		Intended status: Standards Track S. Rose
	Intended status: Standards Track NIST		Expires: April 11, 2011 NIST
	Expires: October 15, 2010 April 13, 2010		October 8, 2010
	Signaling Cryptographic Algorithm Understanding in DNSSEC		Signaling Cryptographic Algorithm Understanding in DNSSEC
	draft-crocker-dnssec-algo-signal-06		draft-crocker-dnssec-algo-signal-07
	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.
	Requirements Language		Requirements Language
	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 RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	Status of This Memo		Status of This Memo
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	Copyright Notice		Copyright Notice
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	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Signaling Algorithm Understood (AU) Using EDNS . . . . . . . . 3		2. Signaling Algorithm Understood (AU) Using EDNS . . . . . . . . 3
	3. Client Considerations . . . . . . . . . . . . . . . . . . . . . 4		3. Client Considerations . . . . . . . . . . . . . . . . . . . . . 4
	3.1. Recommendations for Stub Clients . . . . . . . . . . . . . 4		3.1. Recommendations for Stub Clients . . . . . . . . . . . . . 5
	3.2. Recursive Cache Considerations . . . . . . . . . . . . . . 5		3.2. Recursive Cache Considerations . . . . . . . . . . . . . . 5
	4. Intermediate Middlebox Considerations . . . . . . . . . . . . . 5		4. Intermediate Middlebox Considerations . . . . . . . . . . . . . 5
	5. Server Considerations . . . . . . . . . . . . . . . . . . . . . 5		5. Server Considerations . . . . . . . . . . . . . . . . . . . . . 5
	6. Traffic Analysis Considerations . . . . . . . . . . . . . . . . 5		6. Traffic Analysis Considerations . . . . . . . . . . . . . . . . 6
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
	8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6		8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
	9. Normative References . . . . . . . . . . . . . . . . . . . . . 6		9. Normative References . . . . . . . . . . . . . . . . . . . . . 6
	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 help validators identify which cryptographic		These algorithm codes tells validators which cryptographic algorithm
	algorithm was used to generate the digital signature.		was used to generate the digital signature. Authentication across
			delegation boundries 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 contruct 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 signal to a server which cryptographic algorithms they		resolvers to tell a server which cryptographic and/or hash algorithms
	support in a DNSSEC response. This is done using the EDNS attribute		they support in a DNS query. This is done using the EDNS attribute
	values in the OPT meta-RR [RFC2671].		values 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 algorithms. This algorithm signaling option can		new digital signing and hash algorithms. This algorithm signaling
	be used by zone administrators as a gauge to measure the successful		option can be used by zone administrators as a gauge to measure the
	deployment of code that implements a newly deployed digital signature		successful deployment of code that implements a newly deployed
	algorithm used with DNSSEC. A zone administrator may be able to		digital signature or hash algorithm used with DNSSEC. A zone
	determine when to stop serving the old algorithm when the server sees		administrator may be able to determine when to stop serving the old
	that all or almost all of its clients signal that they are able to		algorithm when the server sees that all or almost all of its clients
	accept the new algorithm.		signal that they are able to accept the new algorithm.
	This draft does not seek to include a formal process for including		This draft does not seek to include another process for including new
	new algorithms for use with DNSSEC. 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 Algorithm Understood (AU) Using EDNS		2. Signaling Algorithm Understood (AU) 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 seeks		are contained in the RDATA of the OPT meta-RR. This document defines
	to define a new EDNS0 option for a client to signal which algorithms		a new EDNS0 option for a client to signal which algorithms the client
	the client supports.		supports.
	The figure below shows how the signally attribute is defined in the		The figure below shows how the signally attribute is defined in the
	RDATA of the OPT RR specified in [RFC2671]:		RDATA of the OPT RR specified in [RFC2671]:
	0 8 16		0 8 16
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| OPTION-CODE (TBD) |		| OPTION-CODE (TBD) |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| OPTION-LENGTH |		| DIGITAL-SIG-LIST-LENGTH |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| ALG-CODE | ... \		| ALG-CODE | ... \
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
			| DS-HASH-LIST-LENGTH |
			+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
			| HASH-CODE | ... \
			+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	OPTION-CODE is the code for the Algorithm Understood (AU) option.		OPTION-CODE is the code for the Algorithm Understood (AU) option.
	Its value is fixed at TBD.		Its value is fixed at TBD.
	OPTION-LENGTH is the length of the data of the attribute in octets.		DIGITAL-SIG-LIST-LENGTH is the length of the list of digital
	DNSSEC algorithm codes are 1 octet long so this value is the number		signature algorithms in octets. DNSSEC algorithm codes are 1 octet
	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 MUST		algorithms that the client indicates as understood. The values
	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 AU option in the OPT		A validating end-system resolver sets the AU 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 first as described in section 2. The end-system resolver		algorithm(s) first as described in section 2. The end-system
	MUST also set the DNSSEC-OK bit [RFC4035] to indicate that it wishes		resolver MUST also set the DNSSEC-OK bit [RFC4035] to indicate that
	to receive DNSSEC RRs in the response.		it wishes to receive DNSSEC RRs in the response.
	Note that when including the PRIVATEDNS (253) and/or the PRIVATEOID		Note that when including the PRIVATEDNS (253) and/or the PRIVATEOID
	(254) codes, the client only indicates that it understands one or		(254) codes, the client only indicates that it understands one or
	more private algorithms but does not indicate which algorithms.		more private algorithms but does not indicate which algorithms.
	3.1. Recommendations for Stub Clients		3.1. Recommendations for Stub Clients
	Typically, stub resolvers rely on an upstream recursive server (or		Typically, stub resolvers rely on an upstream recursive server (or
	cache) to provide a response; any algorithm supportence on the stub		cache) to provide a response; any algorithm support on the stub
	resolver's side could be overruled by the upstream recursive server.		resolver's side could be overruled by the upstream recursive server.
	The AU EDNS option is NOT RECOMMENDED for non-validating stub		The AU EDNS option is NOT RECOMMENDED for non-validating stub
	clients.		clients.
	The exception to the above is that validating stub resolvers which		The exception to the above is that validating stub resolvers which
	set the CD bit in queries MAY set the AU option. In the most common		set the CD bit in queries MAY set the AU option. In the most common
	scenario, the validating stub indicates that it wishes to perform its		scenario, the validating stub indicates that it wishes to perform its
	own validation (via the CD bit) and may therefore wish to indicate		own validation (via the CD bit) and may therefore wish to indicate
	which cryptographic algorithm(s) it supports.		which cryptographic algorithm(s) it supports.
End of changes. 21 change blocks.
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