< draft-ietf-dane-openpgpkey-02.txt		draft-ietf-dane-openpgpkey-03.txt >
	Network Working Group P. Wouters		Network Working Group P. Wouters
	Internet-Draft Red Hat		Internet-Draft Red Hat
	Intended status: Standards Track March 09, 2015		Intended status: Standards Track April 01, 2015
	Expires: September 10, 2015		Expires: October 03, 2015
	Using DANE to Associate OpenPGP public keys with email addresses		Using DANE to Associate OpenPGP public keys with email addresses
	draft-ietf-dane-openpgpkey-02		draft-ietf-dane-openpgpkey-03
	Abstract		Abstract
	OpenPGP is a message format for email (and file) encryption, that		OpenPGP is a message format for email (and file) encryption that
	lacks a standardized lookup mechanism to obtain OpenPGP public keys.		lacks a standardized lookup mechanism to securely obtain OpenPGP
	This document specifies a method for securely publishing and locating		public keys. This document specifies a method for publishing,
	OpenPGP public keys in DNS using a new OPENPGPKEY DNS Resource		locating and verifying OpenPGP public keys in DNS for a specific
	Record.		email address using a new OPENPGPKEY DNS Resource Record. Security
			is provided via DNSSEC.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 September 10, 2015.		This Internet-Draft will expire on October 03, 2015.
	Copyright Notice		Copyright Notice
	Copyright (c) 2015 IETF Trust and the persons identified as the		Copyright (c) 2015 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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3		1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
	2. The OPENPGPKEY Resource Record . . . . . . . . . . . . . . . 3		2. The OPENPGPKEY Resource Record . . . . . . . . . . . . . . . 4
	2.1. The OPENPGPKEY RDATA component . . . . . . . . . . . . . 3		2.1. The OPENPGPKEY RDATA component . . . . . . . . . . . . . 4
	2.2. The OPENPGPKEY RDATA wire format . . . . . . . . . . . . 3		2.2. The OPENPGPKEY RDATA wire format . . . . . . . . . . . . 4
	2.3. The OPENPGPKEY RDATA presentation format . . . . . . . . 4		2.3. The OPENPGPKEY RDATA presentation format . . . . . . . . 4
	3. Location of the OPENPGPKEY record . . . . . . . . . . . . . . 4		3. Location of the OPENPGPKEY record . . . . . . . . . . . . . . 4
	3.1. Email address variants . . . . . . . . . . . . . . . . . 4		3.1. Email address variants . . . . . . . . . . . . . . . . . 5
	4. OpenPGP Key size and DNS . . . . . . . . . . . . . . . . . . 5		4. Application use of OPENPGPKEY . . . . . . . . . . . . . . . . 6
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 5		4.1. Obtaining an OpenPGP key for a specific email address . . 6
	5.1. Response size . . . . . . . . . . . . . . . . . . . . . . 5		4.2. Confirming the validity of an OpenPGP key . . . . . . . . 6
	5.2. Email address information leak . . . . . . . . . . . . . 5		4.3. Verifying an unknown OpenPGP signature . . . . . . . . . 6
	5.3. Forward security of OpenPGP versus DNSSEC . . . . . . . . 6		5. OpenPGP Key size and DNS . . . . . . . . . . . . . . . . . . 6
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	6.1. OPENPGPKEY RRtype . . . . . . . . . . . . . . . . . . . . 7		6.1. Response size . . . . . . . . . . . . . . . . . . . . . . 7
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7		6.2. Email address information leak . . . . . . . . . . . . . 7
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7		6.3. Storage of OPENPGPKEY data . . . . . . . . . . . . . . . 8
	8.1. Normative References . . . . . . . . . . . . . . . . . . 7		6.4. Forward security of OpenPGP versus DNSSEC . . . . . . . . 8
	8.2. Informative References . . . . . . . . . . . . . . . . . 7		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
	Appendix A. Generating OPENPGPKEY records . . . . . . . . . . . 8		7.1. OPENPGPKEY RRtype . . . . . . . . . . . . . . . . . . . . 8
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9		8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
			9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
			9.1. Normative References . . . . . . . . . . . . . . . . . . 9
			9.2. Informative References . . . . . . . . . . . . . . . . . 9
			Appendix A. Generating OPENPGPKEY records . . . . . . . . . . . 10
			Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
	1. Introduction		1. Introduction
	To encrypt a message to a target recipient using OpenPGP [RFC4880],		OpenPGP [RFC4880] public keys are used to encrypt or sign email
	possession of the recipient's OpenPGP public key is required. To		messages and files. To encrypt an email message, the sender's email
	obtain that public key, the sender's email client or MTA needs to		client or MTA needs to know where to find the recipient's OpenPGP
	know where to find the recipient's public key. Once obtained, it		public key. Once obtained, it needs to find some proof that the
	needs to find some proof that the public key found actually belongs		OpenPGP public key found actually belongs to the intended recipient.
	to the intended recipient.
	Obtaining a public key is not a straightforward process as there are		Similarly, when files on a storage media are signed with an OpenPGP
	no trusted standardized locations for publishing OpenPGP public keys		public key that is included on the storage media, this key needs to
	indexed by email address. Instead, OpenPGP clients rely on "well-		be independently verified.
	known key servers" that are accessed using the HTTP Keyserver
	Protocol ("HKP") or manually by users using a variety of differently		Obtaining and verifying an OpenPGP public key is not a
	formatted front-end web pages.		straightforward process as there are no trusted standardized
			locations for publishing OpenPGP public keys indexed by email
			address. Instead, OpenPGP clients rely on "well-known key servers"
			that are accessed using the HTTP Keyserver Protocol ("HKP") or
			manually by users using a variety of differently formatted front-end
			web pages. Worse, some OpenPGP users announce their OpenPGP public
			key fingerprint on social media with no method of validation
			whatsoever.
	Currently deployed key servers have no method of validating any		Currently deployed key servers have no method of validating any
	uploaded OpenPGP public key. The key servers simply store and		uploaded OpenPGP public key. The key servers simply store and
	publish. Anyone can add public keys with any identities and anyone		publish. Anyone can add public keys with any identities and anyone
	can add signatures to any other public key using forged malicious		can add signatures to any other public key using forged malicious
	identities. Furthermore, once uploaded, public keys cannot be		identities. Furthermore, once uploaded, public keys cannot be
	deleted. People who did not pre-sign a key revocation can never		deleted. People who did not pre-sign a key revocation can never
	remove their public key from these key servers once they lose their		remove their public key from these key servers once they lose their
	private key.		private key.
	The lack of a secure means to look up a public key for an email		The lack of a secure means to look up a public key for an email
	address also prevents email clients and MUAs from encrypting a		address prevents email clients and MUAs from encrypting an outgoing
	received email to the target recipient, forcing the software to send		email to the target recipient, forcing the software to send the
	the message unencrypted. Currently deployed MTAs only support		message unencrypted. Currently deployed MTAs only support encrypting
	encrypting the transport of the email, not the email contents itself.		the transport of the email, not the email contents itself, leaving
			the content of the email exposed to anyone with access to any of the
			mail or storage servers used to transport the email from the sender
			to the receiver.
	This document describes a mechanism to associate a user's OpenPGP		This document describes a mechanism to associate a user's OpenPGP
	public key with their email address, using a new DNS RRtype.		public key with their email address, using a new DNS RRtype.
	The proposed new DNS Resource Record type is secured using DNSSEC.		The proposed new DNS Resource Record type is secured using DNSSEC.
	This trust model is not meant to replace the Trust Signature model.		This trust model is not meant to replace the Trust Signature model.
	However, it can be used to encrypt a message that would otherwise		However, it can be used to encrypt a message that would otherwise
	have to be sent out unencrypted, where it could be monitored by a		have to be sent out unencrypted, where it could be monitored by a
	third party in transit or located in plaintext on a storage or email		third party in transit or located in plaintext on a storage or email
	server.		server. This method can also be used to obtain the OpenPGP public
			key which can then be used for manual verification.
	1.1. Terminology		1.1. 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 RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	This document also makes use of standard DNSSEC and DANE terminology.		This document also makes use of standard DNSSEC and DANE terminology.
	See DNSSEC [RFC4033], [RFC4034], [RFC4035], and DANE [RFC6698] for		See DNSSEC [RFC4033], [RFC4034], [RFC4035], and DANE [RFC6698] for
	these terms.		these terms.
	skipping to change at page 3, line 43 ¶		skipping to change at page 4, line 27 ¶
	The OPENPGPKEY DNS resource record (RR) is used to associate an end		The OPENPGPKEY DNS resource record (RR) is used to associate an end
	entity OpenPGP public key with an email address, thus forming a		entity OpenPGP public key with an email address, thus forming a
	"OpenPGP public key association".		"OpenPGP public key association".
	The type value allocated for the OPENPGPKEY RR type is 61. The		The type value allocated for the OPENPGPKEY RR type is 61. The
	OPENPGPKEY RR is class independent. The OPENPGPKEY RR has no special		OPENPGPKEY RR is class independent. The OPENPGPKEY RR has no special
	TTL requirements.		TTL requirements.
	2.1. The OPENPGPKEY RDATA component		2.1. The OPENPGPKEY RDATA component
	The RDATA (or RHS) of an OPENPGPKEY Resource Record contains a single		The RDATA portion of an OPENPGPKEY Resource Record contains a single
	value consisting of a [RFC4880] formatted OpenPGP public keyring.		value consisting of a [RFC4880] formatted OpenPGP public keyring.
	2.2. The OPENPGPKEY RDATA wire format		2.2. The OPENPGPKEY RDATA wire format
	The RDATA Wire Format consists of a single OpenPGP public key as		The RDATA Wire Format consists of a single OpenPGP public key as
	defined in Section 5.5.1.1 of [RFC4880]. Note that this format is		defined in Section 5.5.1.1 of [RFC4880]. Note that this format is
	without ASCII armor or base64 encoding.		without ASCII armor or base64 encoding.
	2.3. The OPENPGPKEY RDATA presentation format		2.3. The OPENPGPKEY RDATA presentation format
	The RDATA Presentation Format, as visible in textual zone files,		The RDATA Presentation Format, as visible in textual zone files,
	consists of a single OpenPGP public key as defined in		consists of a single OpenPGP public key as defined in
	Section 5.5.1.1. of [RFC4880] encoded in Base64 [RFC4648]		Section 5.5.1.1. of [RFC4880] encoded in base64 as defined in
			Section 4 of [RFC4648].
	3. Location of the OPENPGPKEY record		3. Location of the OPENPGPKEY record
	The DNS does not allow the use of all characters that are supported		The DNS does not allow the use of all characters that are supported
	in the "local-part" of email addresses as defined in [RFC2822] and		in the "local-part" of email addresses as defined in [RFC2822] and
	[RFC6530]. Therefore, email addresses are mapped into DNS using the		[RFC6530]. Therefore, email addresses are mapped into DNS using the
	following method:		following method:
	o The user name (the "left-hand side" of the email address, called		o The user name (the "left-hand side" of the email address, called
	the "local-part" in the mail message format definition [RFC2822]		the "local-part" in the mail message format definition [RFC2822]
	and the "local part" in the specification for internationalized		and the "local part" in the specification for internationalized
	email [RFC6530]), is hashed using the SHA2-224 [RFC5754]		email [RFC6530]) should already be encoded in UTF-8 (or its subset
	algorithm, with the hash being represented in its hexadecimal		ASCII). If it is written in another encoding it should be
	representation, to become the left-most label in the prepared		converted to UTF-8. Next, it is turned into lowercase and hashed
	domain name. This does not include the at symbol ("@") that		using the SHA2-256 [RFC5754] algorithm, with the hash truncated to
	separates the left and right sides of the email address.		28 octets and represented in its hexadecimal representation, to
			become the left-most label in the prepared domain name.
			Truncation comes from the right-most octets. This does not
			include the at symbol ("@") that separates the left and right
			sides of the email address.
	o The string "_openpgpkey" becomes the second left-most label in the		o The string "_openpgpkey" becomes the second left-most label in the
	prepared domain name.		prepared domain name.
	o The domain name (the "right-hand side" of the email address,		o The domain name (the "right-hand side" of the email address,
	called the "domain" in RFC 2822) is appended to the result of step		called the "domain" in RFC 2822) is appended to the result of step
	2 to complete the prepared domain name.		2 to complete the prepared domain name.
	For example, to request an OPENPGPKEY resource record for a user		For example, to request an OPENPGPKEY resource record for a user
	whose email address is "hugh@example.com", an OPENPGPKEY query would		whose email address is "hugh@example.com", an OPENPGPKEY query would
	be placed for the following QNAME: "8d5730bd8d76d417bf974c03f59eedb7a		be placed for the following QNAME: "c93f1e400f26708f98cb19d936620da35
	f98cb5c3dc73ea8ebbd54b7._openpgpkey.example.com". The corresponding		eec8f72e57f9eec01c1afd6._openpgpkey.example.com". The corresponding
	RR in the example.com zone might look like (key shortened for		RR in the example.com zone might look like (key shortened for
	formatting):		formatting):
	8d[..]b7._openpgpkey.example.com. IN OPENPGPKEY <base64 public key>		c9[..]d6._openpgpkey.example.com. IN OPENPGPKEY <base64 public key>
	3.1. Email address variants		3.1. Email address variants
	Some email service providers and email software perform automatic		Mail systems usually handle variant forms of local-parts. The most
	mappings of email addresses based on special characters. This can		common variants are upper and lower case, which are now invariably
	complicate finding the OPENPGPKEY record associated with the		treated as equivalent. But many other variants are possible. Some
	dynamically created email address. Some well known examples are		systems allow and ignore "noise" characters such as dots, so local
	listed below		parts johnsmith and John.Smith would be equivalent. Many systems
	o The LHS is case insensitive, Hugh@example.com and HUGH@example.com		allow "extensions" such as john-ext or mary+ext where john or mary is
	map to hugh@example.com. Some email clients also automatically		treated as the effective local-part, and the ext is passed to the
	uppercase the first letter of an email address when typing it in.		recipient for further handling. This can complicate finding the
			OPENPGPKEY record associated with the dynamically created email
			address.
	o Everything after a "+" symbol is dynamc. hugh+string@example.com		[RFC5321] and its predecessors have always made it clear that only
	maps to hugh@example.com.		the recipient MTA is allowed to interpret the local-part of an
			address. A client supporting OPENPGPKEY therefor MUST NOT perform
			any kind of mapping rules based on the email address. As the local-
			part is converted to lowercase before hashing, case sensitivity will
			not cause problems for the OPENPGPKEY lookup.
	o Dots are optional. hugh.daniel@example.com maps to		4. Application use of OPENPGPKEY
	hughdaniel@example.com.
	Software implementing DNS lookup for the OPENPGPKEY RRtype MAY		The OPENPGPKEY record allows an application or service to obtain or
	perform similar translations rules while trying to find the		verify an OpenPGP public key. The lookup result MUST pass DNSSEC
	OPENPGPKEY record.		validation; if validation reaches any state other than "Secure", the
			verification MUST be treated as a failure.
	4. OpenPGP Key size and DNS		4.1. Obtaining an OpenPGP key for a specific email address
			If no OpenPGP public keys are known for an email address, an
			OPENPGPKEY lookup can be performed to discover the OpenPGP public key
			that belongs to a specific email address. This public key can then
			be used to verify a received signed message or can be used to send
			out an encrypted email message.
			4.2. Confirming the validity of an OpenPGP key
			Locally stored OpenPGP public keys are not automatically refreshed.
			If the owner of that key creates a new OpenPGP public key, that owner
			is unable to securely notify all users and applications that have its
			old OpenPGP public key. Applications and users can perform an
			OPENPGPKEY lookup to confirm the locally stored OpenPGP public key is
			still the correct key to use. If verifying a locally stored OpenPGP
			public key and the OpenPGP public key found through DNS is different
			from the locally stored OpenPGP public key, the verification MUST be
			treated as a failure. An application that can interact with the user
			MAY ask the user for guidance.
			4.3. Verifying an unknown OpenPGP signature
			Storage media can be signed using an OpenPGP public key. Even if the
			OpenPGP public key is included on the storage media, it needs to be
			independently validated. OpenPGP public keys contain one or more IDs
			than can have the syntax of an email address. An application can
			perform a lookup for an OPENPGPKEY at the expected location for the
			specific email address to confirm the validity of the OpenPGP public
			key. Once the key has been validated, all files on the storage media
			that have been signed by this key can now be verified.
			5. OpenPGP Key size and DNS
	Due to the expected size of the OPENPGPKEY record, it is recommended		Due to the expected size of the OPENPGPKEY record, it is recommended
	to perform DNS queries for the OPENPGPKEY record using TCP, not UDP.		to perform DNS queries for the OPENPGPKEY record using TCP, not UDP.
	Although the reliability of the transport of large DNS Resource		Although the reliability of the transport of large DNS Resource
	Records has improved in the last years, it is still recommended to		Records has improved in the last years, it is still recommended to
	keep the DNS records as small as possible without sacrificing the		keep the DNS records as small as possible without sacrificing the
	security properties of the public key. The algorithm type and key		security properties of the public key. The algorithm type and key
	size of OpenPGP keys should not be modified to accommodate this		size of OpenPGP keys should not be modified to accommodate this
	section.		section.
	OpenPGP supports various attributes that do not contribute to the		OpenPGP supports various attributes that do not contribute to the
	security of a key, such as an embedded image file. It is recommended		security of a key, such as an embedded image file. It is recommended
	that these properties are not exported to OpenPGP public keyrings		that these properties are not exported to OpenPGP public keyrings
	that are used to create OPENPGPKEY Resource Records. Some OpenPGP		that are used to create OPENPGPKEY Resource Records. Some OpenPGP
	software, for example GnuPG, have support for a "minimal key export"		software, for example GnuPG, have support for a "minimal key export"
	that is well suited to use as OPENPGPKEY RDATA. See Appendix A.		that is well suited to use as OPENPGPKEY RDATA. See Appendix A.
	5. Security Considerations		6. Security Considerations
	OPENPGPKEY usage considerations are published in [OPENPGPKEY-USAGE].		OPENPGPKEY usage considerations are published in [OPENPGPKEY-USAGE].
	5.1. Response size		6.1. Response size
	To prevent amplification attacks, an Authoritative DNS server MAY		To prevent amplification attacks, an Authoritative DNS server MAY
	wish to prevent returning OPENPGPKEY records over UDP unless the		wish to prevent returning OPENPGPKEY records over UDP unless the
	source IP address has been verified with [DNS-COOKIES]. Such servers		source IP address has been verified with [DNS-COOKIES]. Such servers
	MUST NOT return REFUSED, but answer the query with an empty Answer		MUST NOT return REFUSED, but answer the query with an empty Answer
	Section and the truncation flag set ("TC=1).		Section and the truncation flag set ("TC=1").
			6.2. Email address information leak
	5.2. Email address information leak
	Email addresses are not secret. Using them causes their publication.		Email addresses are not secret. Using them causes their publication.
	The hashing of the user name in this document is not a security		The hashing of the user name in this document is not a security
	feature. Publishing OPENPGPKEY records however, will create a list		feature. Publishing OPENPGPKEY records however, will create a list
	of hashes of valid email addresses, which could simplify obtaining a		of hashes of valid email addresses, which could simplify obtaining a
	list of valid email addresses for a particular domain. It is		list of valid email addresses for a particular domain. It is
	desirable to not ease the harvesting of email addresses where		desirable to not ease the harvesting of email addresses where
	possible.		possible.
	The domain name part of the email address is not used as part of the		The domain name part of the email address is not used as part of the
	hash so that hashes can be used in multiple zones deployed using		hash so that hashes can be used in multiple zones deployed using
	skipping to change at page 6, line 27 ¶		skipping to change at page 8, line 5 ¶
	somewhat countered by using NSEC3.		somewhat countered by using NSEC3.
	DNS zones that are signed with DNSSEC using NSEC for denial of		DNS zones that are signed with DNSSEC using NSEC for denial of
	existence are susceptible to zone-walking, a mechanism that allows		existence are susceptible to zone-walking, a mechanism that allows
	someone to enumerate all the OPENPGPKEY hashes in a zone. This can		someone to enumerate all the OPENPGPKEY hashes in a zone. This can
	be used in combination with previously hashed common or short user		be used in combination with previously hashed common or short user
	names (in rainbow tables) to deduce valid email addresses. DNSSEC-		names (in rainbow tables) to deduce valid email addresses. DNSSEC-
	signed zones using NSEC3 for denial of existence instead of NSEC are		signed zones using NSEC3 for denial of existence instead of NSEC are
	significantly harder to brute-force after performing a zone-walk.		significantly harder to brute-force after performing a zone-walk.
	5.3. Forward security of OpenPGP versus DNSSEC		6.3. Storage of OPENPGPKEY data
			Users may have a local key store with OpenPGP public keys. An
			application supporting the use of OPENPGPKEY DNS records MUST NOT
			modify the local key store without explicit confirmation of the user,
			as the application is unaware of the user's personal policy for
			adding, removing or updating their local key store. An application
			MAY warn the user if an OPENPGPKEY record does not match the OpenPGP
			public key in the local key store.
			OpenPGP public keys obtained via OPENPGPKEY records should not be
			stored beyond their DNS TTL value.
			6.4. Forward security of OpenPGP versus DNSSEC
	DNSSEC key sizes are chosen based on the fact that these keys can be		DNSSEC key sizes are chosen based on the fact that these keys can be
	rolled with next to no requirement for security in the future. If		rolled with next to no requirement for security in the future. If
	one doubts the strength or security of the DNSSEC key for whatever		one doubts the strength or security of the DNSSEC key for whatever
	reason, one simply rolls to a new DNSSEC key with a stronger		reason, one simply rolls to a new DNSSEC key with a stronger
	algorithm or larger key size. On the other hand, OpenPGP key sizes		algorithm or larger key size. On the other hand, OpenPGP key sizes
	are chosen based on how many years (or decades) their encryption		are chosen based on how many years (or decades) their encryption
	should remain unbreakable by adversaries that own large scale		should remain unbreakable by adversaries that own large scale
	computational resources.		computational resources.
	skipping to change at page 7, line 5 ¶		skipping to change at page 8, line 42 ¶
	delegated child zones, irrespective of the key size of the OpenPGP		delegated child zones, irrespective of the key size of the OpenPGP
	keypair. Any future messages encrypted with the malicious OpenPGP		keypair. Any future messages encrypted with the malicious OpenPGP
	key could then be read.		key could then be read.
	Therefore, an OpenPGP key obtained via an OPENPGPKEY record can only		Therefore, an OpenPGP key obtained via an OPENPGPKEY record can only
	be trusted as much as the DNS domain can be trusted, and is no		be trusted as much as the DNS domain can be trusted, and is no
	substitute for in-person key verification of the "Web of Trust". See		substitute for in-person key verification of the "Web of Trust". See
	[OPENPGPKEY-USAGE] for more in-depth information on safe usage of		[OPENPGPKEY-USAGE] for more in-depth information on safe usage of
	OPENPGPKEY based OpenPGP keys.		OPENPGPKEY based OpenPGP keys.
	6. IANA Considerations		7. IANA Considerations
	6.1. OPENPGPKEY RRtype		7.1. OPENPGPKEY RRtype
	This document uses a new DNS RR type, OPENPGPKEY, whose value 61 has		This document uses a new DNS RR type, OPENPGPKEY, whose value 61 has
	been allocated by IANA from the Resource Record (RR) TYPEs		been allocated by IANA from the Resource Record (RR) TYPEs
	subregistry of the Domain Name System (DNS) Parameters registry.		subregistry of the Domain Name System (DNS) Parameters registry.
	7. Acknowledgements		8. Acknowledgments
	This document is based on RFC-4255 and draft-ietf-dane-smime whose		This document is based on RFC-4255 and draft-ietf-dane-smime whose
	authors are Paul Hoffman, Jacob Schlyter and W. Griffin. Olafur		authors are Paul Hoffman, Jacob Schlyter and W. Griffin. Olafur
	Gudmundsson provided feedback and suggested various improvements.		Gudmundsson provided feedback and suggested various improvements.
	Willem Toorop contributed the gpg and hexdump command options. Edwin		Willem Toorop contributed the gpg and hexdump command options. Edwin
	Taylor contributed language improvements for various iterations of		Taylor contributed language improvements for various iterations of
	this document.		this document. Text regarding email mappings was taken from draft-
			levine-dns-mailbox whose author is John Levine.
	8. References		9. References
	8.1. Normative References		9.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, 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", RFC		Rose, "DNS Security Introduction and Requirements", RFC
	4033, March 2005.		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 7, line 50 ¶		skipping to change at page 9, line 40 ¶
	[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data		[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
	Encodings", RFC 4648, October 2006.		Encodings", RFC 4648, October 2006.
	[RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R.		[RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R.
	Thayer, "OpenPGP Message Format", RFC 4880, November 2007.		Thayer, "OpenPGP Message Format", RFC 4880, November 2007.
	[RFC5754] Turner, S., "Using SHA2 Algorithms with Cryptographic		[RFC5754] Turner, S., "Using SHA2 Algorithms with Cryptographic
	Message Syntax", RFC 5754, January 2010.		Message Syntax", RFC 5754, January 2010.
	8.2. Informative References		9.2. Informative References
	[DNS-COOKIES]		[DNS-COOKIES]
	Eastlake, Donald., "Domain Name System (DNS) Cookies",		Eastlake, Donald., "Domain Name System (DNS) Cookies",
	draft-ietf-dnsop-cookies (work in progress), February		draft-ietf-dnsop-cookies (work in progress), February
	2015.		2015.
	[OPENPGPKEY-USAGE]		[OPENPGPKEY-USAGE]
	Wouters, P., "Usage considerations with the DNS OPENPGPKEY		Wouters, P., "Usage considerations with the DNS OPENPGPKEY
	record", draft-dane-openpgpkey-usage (work in progress),		record", draft-dane-openpgpkey-usage (work in progress),
	October 2014.		October 2014.
	[RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS		[RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS
	Specification", RFC 2181, July 1997.		Specification", RFC 2181, July 1997.
	[RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April		[RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April
	2001.		2001.
	[RFC3597] Gustafsson, A., "Handling of Unknown DNS Resource Record		[RFC3597] Gustafsson, A., "Handling of Unknown DNS Resource Record
	(RR) Types", RFC 3597, September 2003.		(RR) Types", RFC 3597, September 2003.
			[RFC5233] Murchison, K., "Sieve Email Filtering: Subaddress
			Extension", RFC 5233, January 2008.
			[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
			October 2008.
	[RFC6530] Klensin, J. and Y. Ko, "Overview and Framework for		[RFC6530] Klensin, J. and Y. Ko, "Overview and Framework for
	Internationalized Email", RFC 6530, February 2012.		Internationalized Email", RFC 6530, February 2012.
	[RFC6672] Rose, S. and W. Wijngaards, "DNAME Redirection in the		[RFC6672] Rose, S. and W. Wijngaards, "DNAME Redirection in the
	DNS", RFC 6672, June 2012.		DNS", RFC 6672, June 2012.
	[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication		[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
	of Named Entities (DANE) Transport Layer Security (TLS)		of Named Entities (DANE) Transport Layer Security (TLS)
	Protocol: TLSA", RFC 6698, August 2012.		Protocol: TLSA", RFC 6698, August 2012.
			[RFC7129] Gieben, R. and W. Mekking, "Authenticated Denial of
			Existence in the DNS", RFC 7129, February 2014.
	Appendix A. Generating OPENPGPKEY records		Appendix A. Generating OPENPGPKEY records
	The commonly available GnuPG software can be used to generate the		The commonly available GnuPG software can be used to generate the
	RRdata portion of an OPENPGPKEY record:		RRdata portion of an OPENPGPKEY record:
	gpg --export --export-options export-minimal \		gpg --export --export-options export-minimal \
	hugh@example.com | base64		hugh@example.com | base64
	The --armor or -a option of the gpg command should NOT be used, as it		The --armor or -a option of the gpg command should NOT be used, as it
	adds additional markers around the armored key.		adds additional markers around the armored key.
	skipping to change at page 9, line 15 ¶		skipping to change at page 11, line 15 ¶
	gpg --export --export-options export-minimal \		gpg --export --export-options export-minimal \
	hugh@example.com | wc -c		hugh@example.com | wc -c
	gpg --export --export-options export-minimal \		gpg --export --export-options export-minimal \
	hugh@example.com | hexdump -e \		hugh@example.com | hexdump -e \
	'"\t" /1 "%.2x"' -e '/32 "\n"'		'"\t" /1 "%.2x"' -e '/32 "\n"'
	These values can then be used to generate a generic record (line		These values can then be used to generate a generic record (line
	break has been added for formatting):		break has been added for formatting):
	<SHA2-224(hugh)>._openpgpkey.example.com. IN TYPE61 \# \		<SHA2-256-trunc(hugh)>._openpgpkey.example.com. IN TYPE61 \# \
	<numOctets> <keydata in hex>		<numOctets> <keydata in hex>
	The openpgpkey command in the hash-slinger software can be used to		The openpgpkey command in the hash-slinger software can be used to
	generate complete OPENPGPKEY records		generate complete OPENPGPKEY records
	~> openpgpkey --output rfc hugh@example.com		~> openpgpkey --output rfc hugh@example.com
	8d[...]b7._openpgpkey.example.com. IN OPENPGPKEY mQCNAzIG[...]		c9[..]d6._openpgpkey.example.com. IN OPENPGPKEY mQCNAzIG[...]
	~> openpgpkey --output generic hugh@example.com		~> openpgpkey --output generic hugh@example.com
	8d[...]b7._openpgpkey.example.com. IN TYPE61 \# 2313 99008d03[...]		c9[..]d6._openpgpkey.example.com. IN TYPE61 \# 2313 99008d03[...]
	Author's Address		Author's Address
	Paul Wouters		Paul Wouters
	Red Hat		Red Hat
	Email: pwouters@redhat.com		Email: pwouters@redhat.com
End of changes. 37 change blocks.
	86 lines changed or deleted		168 lines changed or added
This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/