draft-ietf-dnsext-dnssec-rsasha256-14.txt		rfc5702.txt
	DNS Extensions working group J. Jansen		Network Working Group J. Jansen
	Internet-Draft NLnet Labs		Request for Comments: 5702 NLnet Labs
	Intended status: Standards Track June 04, 2009		Category: Standards Track October 2009
	Expires: December 6, 2009
	Use of SHA-2 algorithms with RSA in DNSKEY and RRSIG Resource Records
	for DNSSEC
	draft-ietf-dnsext-dnssec-rsasha256-14
	Status of this Memo
	This Internet-Draft is submitted to IETF in full conformance with the
	provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Use of SHA-2 Algorithms with RSA in
	Task Force (IETF), its areas, and its working groups. Note that		DNSKEY and RRSIG Resource Records for DNSSEC
	other groups may also distribute working documents as Internet-
	Drafts.
	Internet-Drafts are draft documents valid for a maximum of six months		Abstract
	and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."
	The list of current Internet-Drafts can be accessed at		This document describes how to produce RSA/SHA-256 and RSA/SHA-512
	http://www.ietf.org/ietf/1id-abstracts.txt.		DNSKEY and RRSIG resource records for use in the Domain Name System
			Security Extensions (RFC 4033, RFC 4034, and RFC 4035).
	The list of Internet-Draft Shadow Directories can be accessed at		Status of This Memo
	http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on December 6, 2009.		This document specifies an Internet standards track protocol for the
			Internet community, and requests discussion and suggestions for
			improvements. Please refer to the current edition of the "Internet
			Official Protocol Standards" (STD 1) for the standardization state
			and status of this protocol. Distribution of this memo is unlimited.
	Copyright Notice		Copyright Notice
	Copyright (c) 2009 IETF Trust and the persons identified as the		Copyright (c) 2009 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 in effect on the date of		Provisions Relating to IETF Documents
	publication of this document (http://trustee.ietf.org/license-info).		(http://trustee.ietf.org/license-info) in effect on the date of
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	Abstract		include Simplified BSD License text as described in Section 4.e of
			the Trust Legal Provisions and are provided without warranty as
			described in the BSD License.
	This document describes how to produce RSA/SHA-256 and RSA/SHA-512		RFC 5702 DNSSEC RSA/SHA-2 October 2009
	DNSKEY and RRSIG resource records for use in the Domain Name System
	Security Extensions (DNSSEC, RFC 4033, RFC 4034, and RFC 4035).
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction ....................................................2
	2. DNSKEY Resource Records . . . . . . . . . . . . . . . . . . . 3		2. DNSKEY Resource Records .........................................3
	2.1. RSA/SHA-256 DNSKEY Resource Records . . . . . . . . . . . 3		2.1. RSA/SHA-256 DNSKEY Resource Records ........................3
	2.2. RSA/SHA-512 DNSKEY Resource Records . . . . . . . . . . . 4		2.2. RSA/SHA-512 DNSKEY Resource Records ........................3
	3. RRSIG Resource Records . . . . . . . . . . . . . . . . . . . . 4		3. RRSIG Resource Records ..........................................3
	3.1. RSA/SHA-256 RRSIG Resource Records . . . . . . . . . . . . 4		3.1. RSA/SHA-256 RRSIG Resource Records .........................4
	3.2. RSA/SHA-512 RRSIG Resource Records . . . . . . . . . . . . 5		3.2. RSA/SHA-512 RRSIG Resource Records .........................4
	4. Deployment Considerations . . . . . . . . . . . . . . . . . . 5		4. Deployment Considerations .......................................5
	4.1. Key Sizes . . . . . . . . . . . . . . . . . . . . . . . . 5		4.1. Key Sizes ..................................................5
	4.2. Signature Sizes . . . . . . . . . . . . . . . . . . . . . 5		4.2. Signature Sizes ............................................5
	5. Implementation Considerations . . . . . . . . . . . . . . . . 5		5. Implementation Considerations ...................................5
	5.1. Support for SHA-2 signatures . . . . . . . . . . . . . . . 5		5.1. Support for SHA-2 Signatures ...............................5
	5.2. Support for NSEC3 Denial of Existence . . . . . . . . . . 5		5.2. Support for NSEC3 Denial of Existence ......................5
	6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 6		6. Examples ........................................................6
	6.1. RSA/SHA-256 Key and Signature . . . . . . . . . . . . . . 6		6.1. RSA/SHA-256 Key and Signature ..............................6
	6.2. RSA/SHA-512 Key and Signature . . . . . . . . . . . . . . 7		6.2. RSA/SHA-512 Key and Signature ..............................7
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8		7. IANA Considerations .............................................8
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 8		8. Security Considerations .........................................8
	8.1. SHA-1 versus SHA-2 Considerations for RRSIG Resource		8.1. SHA-1 versus SHA-2 Considerations for RRSIG
	Records . . . . . . . . . . . . . . . . . . . . . . . . . 8		Resource Records ...........................................8
	8.2. Signature Type Downgrade Attacks . . . . . . . . . . . . . 8		8.2. Signature Type Downgrade Attacks ...........................8
	9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9		9. Acknowledgments .................................................9
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9		10. References .....................................................9
	10.1. Normative References . . . . . . . . . . . . . . . . . . . 9		10.1. Normative References ......................................9
	10.2. Informative References . . . . . . . . . . . . . . . . . . 9		10.2. Informative References ....................................9
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Introduction		1. Introduction
	The Domain Name System (DNS) is the global hierarchical distributed		The Domain Name System (DNS) is the global, hierarchical distributed
	database for Internet Naming. The DNS has been extended to use		database for Internet Naming. The DNS has been extended to use
	cryptographic keys and digital signatures for the verification of the		cryptographic keys and digital signatures for the verification of the
	authenticity and integrity of its data. RFC 4033 [RFC4033], RFC 4034		authenticity and integrity of its data. [RFC4033], [RFC4034], and
	[RFC4034], and RFC 4035 [RFC4035] describe these DNS Security		[RFC4035] describe these DNS Security Extensions, called DNSSEC.
	Extensions, called DNSSEC.
	RFC 4034 describes how to store DNSKEY and RRSIG resource records,		RFC 4034 describes how to store DNSKEY and RRSIG resource records,
	and specifies a list of cryptographic algorithms to use. This		and specifies a list of cryptographic algorithms to use. This
	document extends that list with the algorithms RSA/SHA-256 and RSA/		document extends that list with the algorithms RSA/SHA-256 and RSA/
	SHA-512, and specifies how to store DNSKEY data and how to produce		SHA-512, and specifies how to store DNSKEY data and how to produce
	RRSIG resource records with these hash algorithms.		RRSIG resource records with these hash algorithms.
	Familiarity with DNSSEC, RSA and the SHA-2 [FIPS.180-3.2008] family		Familiarity with DNSSEC, RSA, and the SHA-2 [FIPS.180-3.2008] family
	of algorithms is assumed in this document.		of algorithms is assumed in this document.
			RFC 5702 DNSSEC RSA/SHA-2 October 2009
	To refer to both SHA-256 and SHA-512, this document will use the name		To refer to both SHA-256 and SHA-512, this document will use the name
	SHA-2. This is done to improve readability. When a part of text is		SHA-2. This is done to improve readability. When a part of text is
	specific for either SHA-256 or SHA-512, their specific names are		specific for either SHA-256 or SHA-512, their specific names are
	used. The same goes for RSA/SHA-256 and RSA/SHA-512, which will be		used. The same goes for RSA/SHA-256 and RSA/SHA-512, which will be
	grouped using the name RSA/SHA-2.		grouped using the name RSA/SHA-2.
	The term "SHA-2" is not officially defined, but is usually used to		The term "SHA-2" is not officially defined but is usually used to
	refer to the collection of the algorithms SHA-224, SHA-256, SHA-384		refer to the collection of the algorithms SHA-224, SHA-256, SHA-384,
	and SHA-512. Since SHA-224 and SHA-384 are not used in DNSSEC, SHA-2		and SHA-512. Since SHA-224 and SHA-384 are not used in DNSSEC, SHA-2
	will only refer to SHA-256 and SHA-512 in this document.		will only refer to SHA-256 and SHA-512 in this document.
	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. DNSKEY Resource Records		2. DNSKEY Resource Records
	The format of the DNSKEY RR can be found in RFC 4034 [RFC4034]. RFC		The format of the DNSKEY RR can be found in [RFC4034]. [RFC3110]
	3110 [RFC3110] describes the use of RSA/SHA-1 for DNSSEC signatures.		describes the use of RSA/SHA-1 for DNSSEC signatures.
	2.1. RSA/SHA-256 DNSKEY Resource Records		2.1. RSA/SHA-256 DNSKEY Resource Records
	RSA public keys for use with RSA/SHA-256 are stored in DNSKEY		RSA public keys for use with RSA/SHA-256 are stored in DNSKEY
	resource records (RRs) with the algorithm number {TBA1}.		resource records (RRs) with the algorithm number 8.
	For interoperability, as in RFC 3110 [RFC3110], the key size of RSA/		For interoperability, as in [RFC3110], the key size of RSA/SHA-256
	SHA-256 keys MUST NOT be less than 512 bits, and MUST NOT be more		keys MUST NOT be less than 512 bits and MUST NOT be more than 4096
	than 4096 bits.		bits.
	2.2. RSA/SHA-512 DNSKEY Resource Records		2.2. RSA/SHA-512 DNSKEY Resource Records
	RSA public keys for use with RSA/SHA-512 are stored in DNSKEY		RSA public keys for use with RSA/SHA-512 are stored in DNSKEY
	resource records (RRs) with the algorithm number {TBA2}.		resource records (RRs) with the algorithm number 10.
	The key size of RSA/SHA-512 keys MUST NOT be less than 1024 bits, and		The key size of RSA/SHA-512 keys MUST NOT be less than 1024 bits and
	MUST NOT be more than 4096 bits.		MUST NOT be more than 4096 bits.
	3. RRSIG Resource Records		3. RRSIG Resource Records
	The value of the signature field in the RRSIG RR follows the RSASSA-		The value of the signature field in the RRSIG RR follows the RSASSA-
	PKCS1-v1_5 signature scheme, and is calculated as follows. The		PKCS1-v1_5 signature scheme and is calculated as follows. The values
	values for the RDATA fields that precede the signature data are		for the RDATA fields that precede the signature data are specified in
	specified in RFC 4034 [RFC4034].		[RFC4034].
			RFC 5702 DNSSEC RSA/SHA-2 October 2009
	hash = SHA-XXX(data)		hash = SHA-XXX(data)
	Here XXX is either 256 or 512, depending on the algorithm used, as		Here XXX is either 256 or 512, depending on the algorithm used, as
	specified in FIPS PUB 180-3 [FIPS.180-3.2008], and "data" is the wire		specified in FIPS PUB 180-3; "data" is the wire format data of the
	format data of the resource record set that is signed, as specified		resource record set that is signed, as specified in [RFC4034].
	in RFC 4034 [RFC4034].
	signature = ( 00 | 01 | FF* | 00 | prefix | hash ) ** e (mod n)		signature = ( 00 | 01 | FF* | 00 | prefix | hash ) ** e (mod n)
	Here "|" is concatenation, "00", "01", "FF" and "00" are fixed octets		Here "|" is concatenation; "00", "01", "FF", and "00" are fixed
	of corresponding hexadecimal value, "e" is the private exponent of		octets of corresponding hexadecimal value; "e" is the private
	the signing RSA key, and "n" is the public modulus of the signing		exponent of the signing RSA key; and "n" is the public modulus of the
	key. The FF octet MUST be repeated the exact number of times so that		signing key. The FF octet MUST be repeated the exact number of times
	the total length of the concatenated term in parentheses equals the		so that the total length of the concatenated term in parentheses
	length of the modulus of the signer's public key ("n").		equals the length of the modulus of the signer's public key ("n").
	The "prefix" is intended to make the use of standard cryptographic		The "prefix" is intended to make the use of standard cryptographic
	libraries easier. These specifications are taken directly from the		libraries easier. These specifications are taken directly from the
	specifications of RSASSA-PKCS1-v1_5 in PKCS #1 v2.1 section 8.2		specifications of RSASSA-PKCS1-v1_5 in PKCS #1 v2.1 (Section 8.2 of
	[RFC3447], and EMSA-PKCS1-v1_5 encoding in PKCS #1 v2.1 section 9.2		[RFC3447]), and EMSA-PKCS1-v1_5 encoding in PKCS #1 v2.1 (Section 9.2
	[RFC3447]. The prefixes for the different algorithms are specified		of [RFC3447]). The prefixes for the different algorithms are
	below.		specified below.
	3.1. RSA/SHA-256 RRSIG Resource Records		3.1. RSA/SHA-256 RRSIG Resource Records
	RSA/SHA-256 signatures are stored in the DNS using RRSIG resource		RSA/SHA-256 signatures are stored in the DNS using RRSIG resource
	records (RRs) with algorithm number {TBA1}.		records (RRs) with algorithm number 8.
	The prefix is the ASN.1 DER SHA-256 algorithm designator prefix as		The prefix is the ASN.1 DER SHA-256 algorithm designator prefix, as
	specified in PKCS #1 v2.1 [RFC3447]:		specified in PKCS #1 v2.1 [RFC3447]:
	hex 30 31 30 0d 06 09 60 86 48 01 65 03 04 02 01 05 00 04 20		hex 30 31 30 0d 06 09 60 86 48 01 65 03 04 02 01 05 00 04 20
	3.2. RSA/SHA-512 RRSIG Resource Records		3.2. RSA/SHA-512 RRSIG Resource Records
	RSA/SHA-512 signatures are stored in the DNS using RRSIG resource		RSA/SHA-512 signatures are stored in the DNS using RRSIG resource
	records (RRs) with algorithm number {TBA2}.		records (RRs) with algorithm number 10.
	The prefix is the ASN.1 DER SHA-512 algorithm designator prefix as		The prefix is the ASN.1 DER SHA-512 algorithm designator prefix, as
	specified in PKCS #1 v2.1 [RFC3447]:		specified in PKCS #1 v2.1 [RFC3447]:
	hex 30 51 30 0d 06 09 60 86 48 01 65 03 04 02 03 05 00 04 40		hex 30 51 30 0d 06 09 60 86 48 01 65 03 04 02 03 05 00 04 40
			RFC 5702 DNSSEC RSA/SHA-2 October 2009
	4. Deployment Considerations		4. Deployment Considerations
	4.1. Key Sizes		4.1. Key Sizes
	Apart from the restrictions in section 2, this document will not		Apart from the restrictions in Section 2, this document will not
	specify what size of keys to use. That is an operational issue and		specify what size of keys to use. That is an operational issue and
	depends largely on the environment and intended use. A good starting		depends largely on the environment and intended use. A good starting
	point for more information would be NIST SP 800-57 [NIST800-57].		point for more information would be NIST SP 800-57 [NIST800-57].
	4.2. Signature Sizes		4.2. Signature Sizes
	In this family of signing algorithms, the size of signatures is		In this family of signing algorithms, the size of signatures is
	related to the size of the key, and not the hashing algorithm used in		related to the size of the key and not to the hashing algorithm used
	the signing process. Therefore, RRSIG resource records produced with		in the signing process. Therefore, RRSIG resource records produced
	RSA/SHA-256 or RSA/SHA-512 will have the same size as those produced		with RSA/SHA-256 or RSA/SHA-512 will have the same size as those
	with RSA/SHA-1, if the keys have the same length.		produced with RSA/SHA-1, if the keys have the same length.
	5. Implementation Considerations		5. Implementation Considerations
	5.1. Support for SHA-2 signatures		5.1. Support for SHA-2 Signatures
	DNSSEC aware implementations SHOULD be able to support RRSIG and		DNSSEC-aware implementations SHOULD be able to support RRSIG and
	DNSKEY resource records created with the RSA/SHA-2 algorithms as		DNSKEY resource records created with the RSA/SHA-2 algorithms as
	defined in this document.		defined in this document.
	5.2. Support for NSEC3 Denial of Existence		5.2. Support for NSEC3 Denial of Existence
	RFC 5155 [RFC5155] defines new algorithm identifiers for existing		[RFC5155] defines new algorithm identifiers for existing signing
	signing algorithms, to indicate that zones signed with these		algorithms, to indicate that zones signed with these algorithm
	algorithm identifiers can use NSEC3 as well as NSEC records to		identifiers can use NSEC3 as well as NSEC records to provide denial
	provide denial of existence. That mechanism was chosen to protect		of existence. That mechanism was chosen to protect implementations
	implementations predating RFC5155 from encountering resource records		predating RFC 5155 from encountering resource records about which
	they could not know about. This document does not define such		they could not know. This document does not define such algorithm
	algorithm aliases.		aliases.
	A DNSSEC validator that implements RSA/SHA-2 MUST be able to validate		A DNSSEC validator that implements RSA/SHA-2 MUST be able to validate
	negative answers in the form of both NSEC and NSEC3 with hash		negative answers in the form of both NSEC and NSEC3 with hash
	algorithm 1, as defined in [RFC5155]. An authoritative server that		algorithm 1, as defined in [RFC5155]. An authoritative server that
	does not implement NSEC3 MAY still serve zones that use RSA/SHA-2		does not implement NSEC3 MAY still serve zones that use RSA/SHA-2
	with NSEC denial of existence.		with NSEC denial of existence.
			RFC 5702 DNSSEC RSA/SHA-2 October 2009
	6. Examples		6. Examples
	6.1. RSA/SHA-256 Key and Signature		6.1. RSA/SHA-256 Key and Signature
	Given a private key with the following values (in Base64):		Given a private key with the following values (in Base64):
	Private-key-format: v1.2		Private-key-format: v1.2
	Algorithm: 8 (RSASHA256)		Algorithm: 8 (RSASHA256)
	Modulus: wVwaxrHF2CK64aYKRUibLiH30KpPuPBjel7E8ZydQW1HYWHfoGm		Modulus: wVwaxrHF2CK64aYKRUibLiH30KpPuPBjel7E8ZydQW1HYWHfoGm
	idzC2RnhwCC293hCzw+TFR2nqn8OVSY5t2Q==		idzC2RnhwCC293hCzw+TFR2nqn8OVSY5t2Q==
	skipping to change at page 6, line 42		skipping to change at page 6, line 40
	kxUdp6p/DlUmObdk= );{id = 9033 (zsk), size = 512b}		kxUdp6p/DlUmObdk= );{id = 9033 (zsk), size = 512b}
	With this key, sign the following RRSet, consisting of 1 A record:		With this key, sign the following RRSet, consisting of 1 A record:
	www.example.net. 3600 IN A 192.0.2.91		www.example.net. 3600 IN A 192.0.2.91
	If the inception date is set at 00:00 hours on January 1st, 2000, and		If the inception date is set at 00:00 hours on January 1st, 2000, and
	the expiration date at 00:00 hours on January 1st, 2030, the		the expiration date at 00:00 hours on January 1st, 2030, the
	following signature should be created:		following signature should be created:
	www.example.net. 3600 IN RRSIG (A 8 3 3600 20300101000000		www.example.net. 3600 IN RRSIG (A 8 3 3600 20300101000000
	20000101000000 9033 example.net. kRCOH6u7l0QGy9qpC9		20000101000000 9033 example.net. kRCOH6u7l0QGy9qpC9
	l1sLncJcOKFLJ7GhiUOibu4teYp5VE9RncriShZNz85mwlMgNEa		l1sLncJcOKFLJ7GhiUOibu4teYp5VE9RncriShZNz85mwlMgNEa
	cFYK/lPtPiVYP4bwg== ;{id = 9033}		cFYK/lPtPiVYP4bwg==);{id = 9033}
			RFC 5702 DNSSEC RSA/SHA-2 October 2009
	6.2. RSA/SHA-512 Key and Signature		6.2. RSA/SHA-512 Key and Signature
	Given a private key with the following values (in Base64):		Given a private key with the following values (in Base64):
	Private-key-format: v1.2		Private-key-format: v1.2
	Algorithm: 10 (RSASHA512)		Algorithm: 10 (RSASHA512)
	Modulus: 0eg1M5b563zoq4k5ZEOnWmd2/BvpjzedJVdfIsDcMuuhE5SQ3pf		Modulus: 0eg1M5b563zoq4k5ZEOnWmd2/BvpjzedJVdfIsDcMuuhE5SQ3pf
	Q7qmdaeMlC6Nf8DKGoUPGPXe06cP27/WRODtxXquSUytkO0kJDk		Q7qmdaeMlC6Nf8DKGoUPGPXe06cP27/WRODtxXquSUytkO0kJDk
	8KX8PtA0+yBWwy7UnZDyCkynO00Uuk8HPVtZeMO1pHtlAGVnc8V		8KX8PtA0+yBWwy7UnZDyCkynO00Uuk8HPVtZeMO1pHtlAGVnc8V
	skipping to change at page 8, line 5		skipping to change at page 8, line 5
	the expiration date at 00:00 hours on January 1st, 2030, the		the expiration date at 00:00 hours on January 1st, 2030, the
	following signature should be created:		following signature should be created:
	www.example.net. 3600 IN RRSIG (A 10 3 3600 20300101000000		www.example.net. 3600 IN RRSIG (A 10 3 3600 20300101000000
	20000101000000 3740 example.net. tsb4wnjRUDnB1BUi+t		20000101000000 3740 example.net. tsb4wnjRUDnB1BUi+t
	6TMTXThjVnG+eCkWqjvvjhzQL1d0YRoOe0CbxrVDYd0xDtsuJRa		6TMTXThjVnG+eCkWqjvvjhzQL1d0YRoOe0CbxrVDYd0xDtsuJRa
	eUw1ep94PzEWzr0iGYgZBWm/zpq+9fOuagYJRfDqfReKBzMweOL		eUw1ep94PzEWzr0iGYgZBWm/zpq+9fOuagYJRfDqfReKBzMweOL
	DiNa8iP5g9vMhpuv6OPlvpXwm9Sa9ZXIbNl1MBGk0fthPgxdDLw		DiNa8iP5g9vMhpuv6OPlvpXwm9Sa9ZXIbNl1MBGk0fthPgxdDLw
	=);{id = 3740}		=);{id = 3740}
			RFC 5702 DNSSEC RSA/SHA-2 October 2009
	7. IANA Considerations		7. IANA Considerations
	This document updates the IANA registry "DNS SECURITY ALGORITHM		This document updates the IANA registry "DNS SECURITY ALGORITHM
	NUMBERS -- per [RFC4035] "		NUMBERS -- per [RFC4035]" (http://www.iana.org/protocols). The
	(http://www.iana.org/assignments/dns-sec-alg-numbers). The following		following entries are added to the registry:
	entries are added to the registry:
	Zone Trans.		Zone Trans.
	Value Description Mnemonic Signing Sec. References		Value Description Mnemonic Signing Sec. References
	{TBA1} RSA/SHA-256 RSASHA256 y * {this memo}		8 RSA/SHA-256 RSASHA256 Y * RFC 5702
	{TBA2} RSA/SHA-512 RSASHA512 y * {this memo}		10 RSA/SHA-512 RSASHA512 Y * RFC 5702
	* There has been no determination of standardization of the use of this		* There has been no determination of standardization of the use of
	algorithm with Transaction Security.		this algorithm with Transaction Security.
	8. Security Considerations		8. Security Considerations
	8.1. SHA-1 versus SHA-2 Considerations for RRSIG Resource Records		8.1. SHA-1 versus SHA-2 Considerations for RRSIG Resource Records
	Users of DNSSEC are encouraged to deploy SHA-2 as soon as software		Users of DNSSEC are encouraged to deploy SHA-2 as soon as software
	implementations allow for it. SHA-2 is widely believed to be more		implementations allow for it. SHA-2 is widely believed to be more
	resilient to attack than SHA-1, and confidence in SHA-1's strength is		resilient to attack than SHA-1, and confidence in SHA-1's strength is
	being eroded by recently-announced attacks. Regardless of whether or		being eroded by recently announced attacks. Regardless of whether or
	not the attacks on SHA-1 will affect DNSSEC, it is believed (at the		not the attacks on SHA-1 will affect DNSSEC, it is believed (at the
	time of this writing) that SHA-2 is the better choice for use in		time of this writing) that SHA-2 is the better choice for use in
	DNSSEC records.		DNSSEC records.
	SHA-2 is considered sufficiently strong for the immediate future, but		SHA-2 is considered sufficiently strong for the immediate future, but
	predictions about future development in cryptography and		predictions about future development in cryptography and
	cryptanalysis are beyond the scope of this document.		cryptanalysis are beyond the scope of this document.
	The signature scheme RSASSA-PKCS1-v1_5 is chosen to match the one		The signature scheme RSASSA-PKCS1-v1_5 is chosen to match the one
	used for RSA/SHA-1 signatures. This should ease implementation of		used for RSA/SHA-1 signatures. This should ease implementation of
	the new hashing algorithms in DNSSEC software.		the new hashing algorithms in DNSSEC software.
	8.2. Signature Type Downgrade Attacks		8.2. Signature Type Downgrade Attacks
	Since each RRSet MUST be signed with each algorithm present in the		Since each RRSet MUST be signed with each algorithm present in the
	DNSKEY RRSet at the zone apex (see [RFC4035] Section 2.2), a		DNSKEY RRSet at the zone apex (see Section 2.2 of [RFC4035]), a
	malicious party cannot filter out the RSA/SHA-2 RRSIG, and force the		malicious party cannot filter out the RSA/SHA-2 RRSIG and force the
	validator to use the RSA/SHA-1 signature if both are present in the		validator to use the RSA/SHA-1 signature if both are present in the
	zone. This should provide resilience against algorithm downgrade		zone. This should provide resilience against algorithm downgrade
	attacks, if the validator supports RSA/SHA-2.		attacks, if the validator supports RSA/SHA-2.
			RFC 5702 DNSSEC RSA/SHA-2 October 2009
	9. Acknowledgments		9. Acknowledgments
	This document is a minor extension to RFC 4034 [RFC4034]. Also, we		This document is a minor extension to [RFC4034]. Also, we try to
	try to follow the documents RFC 3110 [RFC3110] and RFC 4509 [RFC4509]		follow the documents [RFC3110] and [RFC4509] for consistency. The
	for consistency. The authors of and contributors to these documents		authors of and contributors to these documents are gratefully
	are gratefully acknowledged for their hard work.		acknowledged for their hard work.
	The following people provided additional feedback and text: Jaap		The following people provided additional feedback and text: Jaap
	Akkerhuis, Mark Andrews, Roy Arends, Rob Austein, Francis Dupont,		Akkerhuis, Mark Andrews, Roy Arends, Rob Austein, Francis Dupont,
	Miek Gieben, Alfred Hoenes, Paul Hoffman, Peter Koch, Michael St.		Miek Gieben, Alfred Hoenes, Paul Hoffman, Peter Koch, Scott Rose,
	Johns, Scott Rose and Wouter Wijngaards.		Michael St. Johns, and Wouter Wijngaards.
	10. References		10. References
	10.1. Normative References		10.1. Normative References
	[FIPS.180-3.2008]		[FIPS.180-3.2008]
	National Institute of Standards and Technology, "Secure		National Institute of Standards and Technology, "Secure
	Hash Standard", FIPS PUB 180-3, October 2008.		Hash Standard", FIPS PUB 180-3, October 2008.
	[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, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	[RFC3110] Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain		[RFC3110] Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain
	Name System (DNS)", RFC 3110, May 2001.		Name System (DNS)", RFC 3110, May 2001.
	[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",
	skipping to change at page 10, line 6		skipping to change at page 10, line 5
	[NIST800-57]		[NIST800-57]
	Barker, E., Barker, W., Burr, W., Polk, W., and M. Smid,		Barker, E., Barker, W., Burr, W., Polk, W., and M. Smid,
	"Recommendations for Key Management", NIST SP 800-57,		"Recommendations for Key Management", NIST SP 800-57,
	March 2007.		March 2007.
	[RFC3447] Jonsson, J. and B. Kaliski, "Public-Key Cryptography		[RFC3447] Jonsson, J. and B. Kaliski, "Public-Key Cryptography
	Standards (PKCS) #1: RSA Cryptography Specifications		Standards (PKCS) #1: RSA Cryptography Specifications
	Version 2.1", RFC 3447, February 2003.		Version 2.1", RFC 3447, February 2003.
			RFC 5702 DNSSEC RSA/SHA-2 October 2009
	[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.
	[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS		[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
	Security (DNSSEC) Hashed Authenticated Denial of		Security (DNSSEC) Hashed Authenticated Denial of
	Existence", RFC 5155, March 2008.		Existence", RFC 5155, March 2008.
	Author's Address		Author's Address
	Jelte Jansen		Jelte Jansen
	NLnet Labs		NLnet Labs
	Kruislaan 419		Science Park 140
	Amsterdam 1098VA		1098 XG Amsterdam
	NL		NL
	Email: jelte@NLnetLabs.nl		EMail: jelte@NLnetLabs.nl
	URI: http://www.nlnetlabs.nl/		URI: http://www.nlnetlabs.nl/
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