draft-ietf-tls-rfc4366-bis-07.txt		draft-ietf-tls-rfc4366-bis-08.txt
	TLS Working Group Donald Eastlake 3rd		TLS Working Group Donald Eastlake 3rd
	INTERNET-DRAFT Stellar Switches		INTERNET-DRAFT Stellar Switches
	Obsoletes: 4366		Obsoletes: 4366
	Intended status: Proposed Standard		Intended status: Proposed Standard
	Expires: November 13, 2010 May 14, 2010		Expires: November 29, 2010 May 30, 2010
	Transport Layer Security (TLS) Extensions: Extension Definitions		Transport Layer Security (TLS) Extensions: Extension Definitions
	<draft-ietf-tls-rfc4366-bis-07.txt>		<draft-ietf-tls-rfc4366-bis-08.txt>
	Abstract		Abstract
	This document provides specifications for existing TLS extensions. It		This document provides specifications for existing TLS extensions. It
	is a companion document for the TLS 1.2 specification [RFC5246]. The		is a companion document for the TLS 1.2 specification [RFC5246]. The
	extensions specified are server_name, max_fragment_length,		extensions specified are server_name, max_fragment_length,
	client_certificate_url, trusted_ca_keys, truncated_hmac, and		client_certificate_url, trusted_ca_keys, truncated_hmac, and
	status_request.		status_request.
	Status of This Memo		Status of This Memo
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	Acknowledgements		Acknowledgements
	This draft is based on material from RFC 4366 for which the authors		This draft is based on material from RFC 4366 for which the authors
	were S. Blake-Wilson, M. Nystron, D. Hopwood, J. Mikkelsen, and T.		were S. Blake-Wilson, M. Nystron, D. Hopwood, J. Mikkelsen, and T.
	Wright.		Wright.
	Table of Contents		Table of Contents
	1. Introduction............................................4		1. Introduction............................................4
	1.1 Specific Extensions Covered............................4		1.1 Specific Extensions Covered............................4
	1.2 Conventions Used in This Document......................5		1.2 Conventions Used in This Document......................6
	2. Extensions to the Handshake Protocol....................6		2. Extensions to the Handshake Protocol....................7
	3. Server Name Indication..................................7		3. Server Name Indication..................................8
	4. Maximum Fragment Length Negotiation.....................9		4. Maximum Fragment Length Negotiation....................10
	5. Client Certificate URLs................................11		5. Client Certificate URLs................................12
	6. Trusted CA Indication..................................14		6. Trusted CA Indication..................................15
	7. Truncated HMAC.........................................16		7. Truncated HMAC.........................................17
	8. Certificate Status Request.............................17		8. Certificate Status Request.............................18
	9. Error Alerts...........................................19		9. Error Alerts...........................................20
	10. IANA Considerations...................................20
	11. Security Considerations...............................20		10. IANA Considerations...................................21
	11.1 Security Considerations for server_name..............20		11. Security Considerations...............................21
	11.2 Security Considerations for max_fragment_length......20		11.1 Security Considerations for server_name..............21
	11.3 Security Considerations for client_certificate_url...21		11.2 Security Considerations for max_fragment_length......21
	11.4 Security Considerations for trusted_ca_keys..........22		11.3 Security Considerations for client_certificate_url...22
	11.5 Security Considerations for truncated_hmac...........22		11.4 Security Considerations for trusted_ca_keys..........23
	11.6 Security Considerations for status_request...........23		11.5 Security Considerations for truncated_hmac...........23
			11.6 Security Considerations for status_request...........24
	12. Normative References..................................24		12. Normative References..................................25
	13. Informative References................................24		13. Informative References................................25
	Annex A: pkipath MIME Type Registration...................26		Annex A: pkipath MIME Type Registration...................27
	Annex B: Changes from RFC 4366............................28		Annex B: Changes from RFC 4366............................29
	INTERNET-DRAFT TLS Extension Definitions		INTERNET-DRAFT TLS Extension Definitions
	1. Introduction		1. Introduction
	The TLS (Transport Layer Security) Protocol Version 1.2 is specified		The TLS (Transport Layer Security) Protocol Version 1.2 is specified
	in [RFC5246]. That specification includes the framework for		in [RFC5246]. That specification includes the framework for
	extensions to TLS, considerations in designing such extensions (see		extensions to TLS, considerations in designing such extensions (see
	Section 7.4.1.4 of [RFC5246]), and IANA Considerations for the		Section 7.4.1.4 of [RFC5246]), and IANA Considerations for the
	allocation of new extension code points; however, it does not specify		allocation of new extension code points; however, it does not specify
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	TLS clients and servers may use the extensions described in this		TLS clients and servers may use the extensions described in this
	document. The extensions are designed to be backwards compatible,		document. The extensions are designed to be backwards compatible,
	meaning that TLS clients that support the extensions can talk to TLS		meaning that TLS clients that support the extensions can talk to TLS
	servers that do not support the extensions, and vice versa.		servers that do not support the extensions, and vice versa.
	Note that any messages associated with these extensions that are sent		Note that any messages associated with these extensions that are sent
	during the TLS handshake MUST be included in the hash calculations		during the TLS handshake MUST be included in the hash calculations
	involved in "Finished" messages.		involved in "Finished" messages.
	Note also that all the extensions defined in this section are		Note also that all the extensions defined in this section are
	relevant only when a session is initiated. When a client includes		relevant only when a session is initiated. A client that requests
	one or more of the defined extension types in an extended client		session resumption does not in general know whether the server will
	hello while requesting session resumption:		accept this request, and therefore it SHOULD send the same extensions
			as it would send if it were not attempting resumption. When a client
			includes one or more of the defined extension types in an extended
			client hello while requesting session resumption:
			- The server name indication extension MAY be used by the server
			when deciding whether or not to resume a session as described
			in section 3.
	- If the resumption request is denied, the use of the extensions		- If the resumption request is denied, the use of the extensions
	is negotiated as normal.		is negotiated as normal.
	- If, on the other hand, the older session is resumed, then the		- If, on the other hand, the older session is resumed, then the
	server MUST ignore the extensions and send a server hello		server MUST ignore the extensions and send a server hello
	containing none of the extension types. In this case, the		containing none of the extension types. In this case, the
	functionality of these extensions negotiated during the		functionality of these extensions negotiated during the
	original session initiation is applied to the resumed session.		original session initiation is applied to the resumed session.
			INTERNET-DRAFT TLS Extension Definitions
	1.2 Conventions Used in This Document		1.2 Conventions Used 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 RFC 2119.
	INTERNET-DRAFT TLS Extension Definitions		INTERNET-DRAFT TLS Extension Definitions
	2. Extensions to the Handshake Protocol		2. Extensions to the Handshake Protocol
	This document specifies the use of two new handshake messages,		This document specifies the use of two new handshake messages,
	"CertificateURL" and "CertificateStatus". These messages are		"CertificateURL" and "CertificateStatus". These messages are
	described in Section 5 and Section 8, respectively. The new		described in Section 5 and Section 8, respectively. The new
	handshake message structure therefore becomes:		handshake message structure therefore becomes:
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	supported name type.		supported name type.
	A server that receives a client hello containing the "server_name"		A server that receives a client hello containing the "server_name"
	extension MAY use the information contained in the extension to guide		extension MAY use the information contained in the extension to guide
	its selection of an appropriate certificate to return to the client,		its selection of an appropriate certificate to return to the client,
	and/or other aspects of security policy. In this event, the server		and/or other aspects of security policy. In this event, the server
	SHALL include an extension of type "server_name" in the (extended)		SHALL include an extension of type "server_name" in the (extended)
	server hello. The "extension_data" field of this extension SHALL be		server hello. The "extension_data" field of this extension SHALL be
	empty.		empty.
	When the server resumes a session, the server_name extension is		When the server is deciding whether or not to accept a request to
	ignored.		resume a session, the contents of a server_name extension MAY be used
			in the lookup of the session in the session cache. The client SHOULD
			include the same server_name extension in session resumption request
			as it did in the full handshake that established the session. A
			server that implements this extension MUST NOT accept the request to
			resume the session if the server_name extension contains a different
			name. Instead, it proceeds with a full handshake to establish a new
			session. When resuming a session, the server MUST NOT include a
			server_name extension in the server hello.
	If an application negotiates a server name using an application		If an application negotiates a server name using an application
	protocol and then upgrades to TLS, and if a server_name extension is		protocol and then upgrades to TLS, and if a server_name extension is
	sent, then the extension SHOULD contain the same name that was		sent, then the extension SHOULD contain the same name that was
	negotiated in the application protocol. If the server_name is		negotiated in the application protocol. If the server_name is
	established in the TLS session handshake, the client SHOULD NOT		established in the TLS session handshake, the client SHOULD NOT
	attempt to request a different server name at the application layer.		attempt to request a different server name at the application layer.
	INTERNET-DRAFT TLS Extension Definitions		INTERNET-DRAFT TLS Extension Definitions
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	[RFC2712] Medvinsky, A. and M. Hur, "Addition of Kerberos Cipher		[RFC2712] Medvinsky, A. and M. Hur, "Addition of Kerberos Cipher
	Suites to Transport Layer Security (TLS)", RFC 2712, October 1999.		Suites to Transport Layer Security (TLS)", RFC 2712, October 1999.
	[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security		[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
	(TLS) Protocol Version 1.1", RFC 4346, April 2006.		(TLS) Protocol Version 1.1", RFC 4346, April 2006.
	[RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,		[RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,
	and T. Wright, "Transport Layer Security (TLS) Extensions", RFC 4366,		and T. Wright, "Transport Layer Security (TLS) Extensions", RFC 4366,
	April 2006.		April 2006.
	[X509-4th] ITU-T Recommendation X.509 (2000) | ISO/IEC 9594-8:2001,
	INTERNET-DRAFT TLS Extension Definitions		INTERNET-DRAFT TLS Extension Definitions
			[X509-4th] ITU-T Recommendation X.509 (2000) | ISO/IEC 9594-8:2001,
	"Information Systems - Open Systems Interconnection - The Directory:		"Information Systems - Open Systems Interconnection - The Directory:
	Public key and attribute certificate frameworks."		Public key and attribute certificate frameworks."
	[X509-4th-TC1] ITU-T Recommendation X.509(2000) Corrigendum 1(2001) |		[X509-4th-TC1] ITU-T Recommendation X.509(2000) Corrigendum 1(2001) |
	ISO/IEC 9594-8:2001/Cor.1:2002, Technical Corrigendum 1 to ISO/IEC		ISO/IEC 9594-8:2001/Cor.1:2002, Technical Corrigendum 1 to ISO/IEC
	9594:8:2001.		9594:8:2001.
	INTERNET-DRAFT TLS Extension Definitions		INTERNET-DRAFT TLS Extension Definitions
	Annex A: pkipath MIME Type Registration		Annex A: pkipath MIME Type Registration
	skipping to change at page 28, line 24		skipping to change at page 29, line 24
	extensions. RFC 4366 was associated with RFC 4346, TLS 1.1. The		extensions. RFC 4366 was associated with RFC 4346, TLS 1.1. The
	client and server Hello extension mechanisms have been moved into RFC		client and server Hello extension mechanisms have been moved into RFC
	5246, TLS 1.2, so this document, which is associated with RFC 5246,		5246, TLS 1.2, so this document, which is associated with RFC 5246,
	includes only the handshake extension mechanisms and the specific		includes only the handshake extension mechanisms and the specific
	extensions from RFC 4366. RFC 5246 also specifies the unknown		extensions from RFC 4366. RFC 5246 also specifies the unknown
	extension error and new extension specification considerations so		extension error and new extension specification considerations so
	that material has been removed from this document.		that material has been removed from this document.
	The Server Name extension now specifies only ASCII representation,		The Server Name extension now specifies only ASCII representation,
	eliminating UTF-8. It is provided that the ServerNameList can contain		eliminating UTF-8. It is provided that the ServerNameList can contain
	more only one name of any particular name_type.		more only one name of any particular name_type. Provision was added
			for the user using the server_name extension in deciding whether or
			not to resume a session. Furthermores, this extensions should be the
			same in a session resumption request as it was in the full handshake
			that established the session. Such a resumption request must not be
			accepted if the server_name extension is different but instead a full
			handshake must be done to possibly establish a new session.
	The Client Certificate URLs extension has been changed to make the		The Client Certificate URLs extension has been changed to make the
	presence of a hash mandatory.		presence of a hash mandatory.
	For the case of DTLS, the requirement to report an overflow of the		For the case of DTLS, the requirement to report an overflow of the
	negotiated maximum fragment length is made conditional on passing		negotiated maximum fragment length is made conditional on passing
	authentication.		authentication.
	The material was also re-organized in minor ways. For example,		The material was also re-organized in minor ways. For example,
	information as to which errors are fatal is moved from the one "Error		information as to which errors are fatal is moved from the one "Error
	skipping to change at page 29, line 14		skipping to change at page 30, line 14
	INTERNET-DRAFT TLS Extension Definitions		INTERNET-DRAFT TLS Extension Definitions
	Author's Address		Author's Address
	Donald Eastlake 3rd		Donald Eastlake 3rd
	Stellar Switches, Inc.		Stellar Switches, Inc.
	155 Beaver Street		155 Beaver Street
	Milford, MA 01757 USA		Milford, MA 01757 USA
	Tel: +1-508-634-2066		Tel: +1-508-333-2270
	Email: d3e3e3@gmail.com		Email: d3e3e3@gmail.com
	INTERNET-DRAFT TLS Extension Definitions		INTERNET-DRAFT TLS Extension Definitions
	Copyright and IPR Provisions		Copyright and IPR Provisions
	Copyright (c) 2010 IETF Trust and the persons identified as the		Copyright (c) 2010 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
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