< draft-ietf-tls-oob-pubkey-04.txt		draft-ietf-tls-oob-pubkey-05.txt >
	TLS P. Wouters		TLS P. Wouters, Ed.
	Internet-Draft Red Hat		Internet-Draft Red Hat
	Intended status: Standards Track J. Gilmore		Intended status: Standards Track H. Tschofenig, Ed.
	Expires: January 17, 2013		Expires: April 25, 2013 Nokia Siemens Networks
			J. Gilmore
	S. Weiler		S. Weiler
	SPARTA, Inc.		SPARTA, Inc.
	T. Kivinen		T. Kivinen
	AuthenTec		AuthenTec
	H. Tschofenig		October 22, 2012
	Nokia Siemens Networks
	July 16, 2012
	Out-of-Band Public Key Validation for Transport Layer Security		Out-of-Band Public Key Validation for Transport Layer Security (TLS)
	draft-ietf-tls-oob-pubkey-04.txt		draft-ietf-tls-oob-pubkey-05.txt
	Abstract		Abstract
	This document specifies a new certificate type for exchanging raw		This document specifies a new certificate type for exchanging raw
	public keys in Transport Layer Security (TLS) and Datagram Transport		public keys in Transport Layer Security (TLS) and Datagram Transport
	Layer Security (DTLS) for use with out-of-band public key validation.		Layer Security (DTLS) for use with out-of-band public key validation.
	Currently, TLS authentication can only occur via X.509-based Public		Currently, TLS authentication can only occur via X.509-based Public
	Key Infrastructure (PKI) or OpenPGP certificates. By specifying a		Key Infrastructure (PKI) or OpenPGP certificates. By specifying a
	minimum resource for raw public key exchange, implementations can use		minimum resource for raw public key exchange, implementations can use
	alternative public key validation methods.		alternative public key validation methods.
	skipping to change at page 2, line 6 ¶		skipping to change at page 2, line 6 ¶
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	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2012 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
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	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
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	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
	3. New TLS Extensions . . . . . . . . . . . . . . . . . . . . . . 4		3. New TLS Extension . . . . . . . . . . . . . . . . . . . . . . 4
	4. TLS Handshake Extension . . . . . . . . . . . . . . . . . . . 5		4. TLS Handshake Extension . . . . . . . . . . . . . . . . . . . 7
	4.1. Client Hello . . . . . . . . . . . . . . . . . . . . . . . 5		4.1. Client Hello . . . . . . . . . . . . . . . . . . . . . . . 7
	4.2. Server Hello . . . . . . . . . . . . . . . . . . . . . . . 6		4.2. Server Hello . . . . . . . . . . . . . . . . . . . . . . . 7
	4.3. Certificate Request . . . . . . . . . . . . . . . . . . . 6		4.3. Certificate Request . . . . . . . . . . . . . . . . . . . 8
	4.4. Certificate Payload . . . . . . . . . . . . . . . . . . . 6		4.4. Other Handshake Messages . . . . . . . . . . . . . . . . . 8
	4.5. Other TLS Messages . . . . . . . . . . . . . . . . . . . . 6		4.5. Client authentication . . . . . . . . . . . . . . . . . . 8
	5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 6		5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 9		6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
	8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10		8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11		9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
	9.1. Normative References . . . . . . . . . . . . . . . . . . . 11		9.1. Normative References . . . . . . . . . . . . . . . . . . . 13
	9.2. Informative References . . . . . . . . . . . . . . . . . . 11		9.2. Informative References . . . . . . . . . . . . . . . . . . 13
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
	1. Introduction		1. Introduction
	Traditionally, TLS server public keys are obtained in PKIX containers		Traditionally, TLS server public keys are obtained in PKIX containers
	in-band using the TLS handshake and validated using trust anchors		in-band using the TLS handshake and validated using trust anchors
	based on a [PKIX] certification authority (CA). This method can add		based on a [PKIX] certification authority (CA). This method can add
	a complicated trust relationship that is difficult to validate.		a complicated trust relationship that is difficult to validate.
	Examples of such complexity can be seen in [Defeating-SSL].		Examples of such complexity can be seen in [Defeating-SSL].
	Alternative methods are available that allow a TLS client to obtain		Alternative methods are available that allow a TLS client to obtain
	the TLS server public key:		the TLS server public key:
	o The TLS server public key is obtained from a DNSSEC secured		o The TLS server public key is obtained from a DNSSEC secured
	resource records using DANE [I-D.ietf-dane-protocol].		resource records using DANE [RFC6698].
	o The TLS server public key is obtained from a [PKIX] certificate		o The TLS server public key is obtained from a [PKIX] certificate
	chain from an Lightweight Directory Access Protocol (LDAP) [LDAP]		chain from an Lightweight Directory Access Protocol (LDAP) [LDAP]
	server.		server.
	o The TLS client and server public key is provisioned into the		o The TLS client and server public key is provisioned into the
	operating system firmware image, and updated via software updates.		operating system firmware image, and updated via software updates.
	Some smart objects use the UDP-based Constrained Application Protocol		Some smart objects use the UDP-based Constrained Application Protocol
	(CoAP) [I-D.ietf-core-coap] to interact with a Web server to upload		(CoAP) [I-D.ietf-core-coap] to interact with a Web server to upload
	sensor data at a regular intervals, such as temperature readings.		sensor data at a regular intervals, such as temperature readings.
	CoAP [I-D.ietf-core-coap] can utilize DTLS for securing the client-		CoAP [I-D.ietf-core-coap] can utilize DTLS for securing the client-
	to-server communication. As part of the manufacturing process, the		to-server communication. As part of the manufacturing process, the
	embeded device may be configured with the address and the public key		embeded device may be configured with the address and the public key
	of a dedicated CoAP server, as well as a public key for the client		of a dedicated CoAP server, as well as a public key for the client
	itself. The usage of X.509-based PKIX certificates [PKIX] does not		itself. The usage of X.509-based PKIX certificates [PKIX] may not
	suit all smart object deployments and would therefore be an		suit all smart object deployments and would therefore be an
	unneccesarry burden.		unneccesarry burden.
	The Transport Layer Security (TLS) Protocol Version 1.2 [RFC5246]		The Transport Layer Security (TLS) Protocol Version 1.2 [RFC5246]
	provides a framework for extensions to TLS as well as guidelines for		provides a framework for extensions to TLS as well as guidelines for
	designing such extensions. This document defines an extension to		designing such extensions. This document defines an extension to
	indicate the support for raw public keys.		indicate the support for raw public keys.
	2. Terminology		2. 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].
	3. New TLS Extensions		3. New TLS Extension
	In order to indicate the support for multiple certificate types two		This section describes the changes to the TLS handshake message
	new extensions are defined by this specification with the following		contents when raw public key certificates are to be used. Figure 3
	semantic:		illustrates the exchange of messages as described in the sub-sections
			below. The client and the server exchange the newly defined
			certificate_type extension to indicate their ability and desire to
			exchange raw public keys. These raw public keys, in the form of a
			SubjectPublicKeyInfo structure, are then carried inside the
			certificate payload. The SubjectPublicKeyInfo structure is defined
			in Section 4.1 of RFC 5280. Note that the SubjectPublicKeyInfo block
			does not only contain the raw keys, such as the public exponent and
			the modulus of an RSA public key, but also an algorithm identifier.
			The structure, as shown in Figure 1, is encoded in an ASN.1 format
			and therefore contains length information as well.
	cert-send: The certificate payload in this message contains a		SubjectPublicKeyInfo ::= SEQUENCE {
	certificate of the type indicated by this extension.		algorithm AlgorithmIdentifier,
			subjectPublicKey BIT STRING }
	cert-receive: By including this extension an entity indicates that		Figure 1: SubjectPublicKeyInfo ASN.1 Structure.
	it is able to recieve and process the indicated certificate types.
	This list is sorted by preference.
	enum { X.509(0), RawPublicKey(1), (255) } CertType;		The algorithm identifiers are Object Identifiers (OIDs). RFC 3279
			[RFC3279], for example, defines the following OIDs shown in Figure 2.
	CertType cert-receive <1..2^8-1>;		Key Type | Document | OID
			-----------------------+----------------------------+-------------------
			RSA | Section 2.3.1 of RFC 3279 | 1.2.840.113549.1.1
			.......................|............................|...................
			Digital Signature | |
			Algorithm (DSS) | Section 2.3.2 of RFC 3279 | 1.2.840.10040.4.1
			.......................|............................|...................
			Elliptic Curve | |
			Digital Signature | |
			Algorithm (ECDSA) | Section 2.3.5 of RFC 3279 | 1.2.840.10045.2.1
			-----------------------+----------------------------+-------------------
	CertType cert-send;		Figure 2: Example Algorithm Identifiers.
	Figure 1: New TLS Extension Structures		client_hello,
			certificate_type ->
	No new cipher suites are required for use with raw public keys. All		<- server_hello,
	existing cipher suites that support a key exchange method compatible		certificate_type,
	with the key in the certificate can be used in combination with raw		certificate,
	public key certificate types.		server_key_exchange,
			certificate_request,
			server_hello_done
			certificate,
			client_key_exchange,
			certificate_verify,
			change_cipher_spec,
			finished ->
	4. TLS Handshake Extension		<- change_cipher_spec,
			finished
	This section describes the semantic of the 'cert-send' and the 'cert-		Application Data <-------> Application Data
	receive' extensions for the different handshake messages.
	4.1. Client Hello		Figure 3: Basic Raw Public Key TLS Exchange.
	To allow a TLS client to indicate that it is able to receive a		The "certificate_type" TLS extension carries a list of supported
	certificate of a specific type it MAY include the 'cert-receive'		certificate types the client can send and receive, sorted by client
	extension in the client hello message. To indicate the ability to		preference. Two values are defined for each certificate types to
	process a raw public key by the server the TLS client MUST include		differentiate whether a client or a server is able to process a
	the 'cert-receive' with the value one (1) (indicating "RawPublicKey")		certificate of a specific type or can also send it. This extension
	in the list of supported certificate types. If a TLS client only		MUST be omitted if the client only supports X.509 certificates. The
	supports X.509 certificates it MAY include this extension to indicate		"extension_data" field of this extension contains a CertTypeExtension
	support for it.		structure.
	Future documents may define additional certificate types that require		Note that the CertTypeExtension structure is being used both by the
	addition values to be registered.		client and the server, even though the structure is only specified
			once in this document.
	Note: No new cipher suites are required to use raw public keys. All		The structure of the CertTypeExtension is defined as follows:
			enum { client, server } ClientOrServerExtension;
			enum { X.509-Accept (0),
			X.509-Offer (1),
			RawPublicKey-Accept (2),
			RawPublicKey-Offer (3),
			(255)
			} CertificateType;
			struct {
			select(ClientOrServerExtension)
			case client:
			CertificateType certificate_types<1..2^8-1>;
			case server:
			CertificateType certificate_type;
			}
			} CertTypeExtension;
			Figure 4: CertTypeExtension Structure.
			No new cipher suites are required to use raw public keys. All
	existing cipher suites that support a key exchange method compatible		existing cipher suites that support a key exchange method compatible
	with the defined extension can be used.		with the defined extension can be used.
	4.2. Server Hello		4. TLS Handshake Extension
	If the server receives a client hello that contains the 'cert-		4.1. Client Hello
	receive' extension then two outcomes are possible. The server MUST
	either select a certificate type from client-provided list or
	terminate the session with a fatal alert of type
	"unsupported_certificate". In the former case the procedure in
	Section 4.4 MUST be followed.
	4.3. Certificate Request		In order to indicate the support of out-of-band raw public keys,
			clients MUST include an extension of type "certificate_type" to the
			extended client hello message. The "certificate_type" TLS extension
			is assigned the value of [TBD] from the TLS ExtensionType registry.
			This value is used as the extension number for the extensions in both
			the client hello message and the server hello message. The hello
			extension mechanism is described in TLS 1.2 [RFC5246].
	The Certificate Request payload sent by the TLS server to the TLS		4.2. Server Hello
	client MUST be accompanied by a 'cert-receive' extension, which
	indicates to the TLS client the certificate type the server supports.
	4.4. Certificate Payload		If the server receives a client hello that contains the
			"certificate_type" extension and chooses a cipher suite then two
			outcomes are possible. The server MUST either select a certificate
			type from the CertificateType field in the extended client hello or
			terminate the session with a fatal alert of type
			"unsupported_certificate".
	Certificate payloads MUST be accompanied by a 'cert-send' extension,		The certificate type selected by the server is encoded in a
	which indicates the certificate format found in the Certificate		CertTypeExtension structure, which is included in the extended server
	payload itself.		hello message using an extension of type "certificate_type". Servers
			that only support X.509 certificates MAY omit including the
			"certificate_type" extension in the extended server hello.
	The list of supported certificate types to choose from MUST have been		If the client supports the receiption of raw public keys and the
	obtained via the 'cert-receive' extension. This ensures that a		server is able to provide such a raw public key then the TLS server
	Certificate payload only contains a certificate type that is also		MUST place the SubjectPublicKeyInfo structure into the Certificate
	supported by the recipient.		payload. The public key MUST match the selected key exchange
			algorithm.
	When the 'RawPublicKey' certificate type is selected then the		4.3. Certificate Request
	SubjectPublicKeyInfo structure MUST be placed into the Certificate
	payload. The type of the asymmetric key MUST match the selected key
	exchange algorithm.
	4.5. Other TLS Messages		The semantics of this message remain the same as in the TLS
			specification.
			4.4. Other Handshake Messages
	All the other handshake messages are identical to the TLS		All the other handshake messages are identical to the TLS
	specification.		specification.
			4.5. Client authentication
			Client authentication by the TLS server is supported only through
			authentication of the received client SubjectPublicKeyInfo via an
			out-of-band method
	5. Examples		5. Examples
	Figure 2, Figure 3, and Figure 4 illustrate example message		Figure 5, Figure 6, and Figure 7 illustrate example message
	exchanges.		exchanges.
	The first example shows an exchange where the TLS client indicates		The first example shows an exchange where the TLS client indicates
	its ability to process two certificate types, namely raw public keys		its ability to process two certificate types, namely raw public keys
	and X.509 certificates via the 'cert-receive' extension (see [1]).		and X.509 certificates via the 'certificate_type' extension in [1].
	When the TLS server receives the client hello it processes the cert-		When the TLS server receives the client hello it processes the
	receive extension and since it also has a raw public key it indicates		certificate_type extension and since it also has a raw public key it
	in [2] that it had choosen to place the SubjectPublicKeyInfo		indicates in [2] that it had choosen to place the
	structure into the Certificate payload (see [3]). The client uses		SubjectPublicKeyInfo structure into the Certificate payload (see
	this raw public key in the TLS handshake and an out-of-band		[3]). The client uses this raw public key in the TLS handshake and
	technique, such as DANE, to verify its validatity.		an out-of-band technique, such as DANE, to verify its validatity.
	client_hello,		client_hello,
	cert-receive=(RawPublicKey, X.509) -> // [1]		certificate_type=(RawPublicKey-Accept) -> // [1]
	<- server_hello,		<- server_hello,
	cert-send=RawPublicKey, // [2]		certificate_type=(RawPublicKey-Offer), // [2]
	certificate, // [3]		certificate, // [3]
	server_key_exchange,		server_key_exchange,
	server_hello_done		server_hello_done
	client_key_exchange,		client_key_exchange,
	change_cipher_spec,		change_cipher_spec,
	finished ->		finished ->
	<- change_cipher_spec,		<- change_cipher_spec,
	finished		finished
	Application Data <-------> Application Data		Application Data <-------> Application Data
	Figure 2: Example with Raw Public Key provided by the TLS Server		Figure 5: Example with Raw Public Key provided by the TLS Server
	In our second example the TLS client and the TLS server use raw		In our second example both the TLS client and the TLS server use raw
	public keys. This is a use case envisioned for smart object		public keys. This is a use case envisioned for smart object
	networking. The TLS client in this case is an embedded device that		networking. The TLS client in this case is an embedded device that
	only supports raw public keys and therefore it indicates this		only supports raw public keys and therefore it indicates this
	capability via the 'cert-receive' extension in [1]. As in the		capability via the 'certificate_type' extension in [1]. As in the
	previously shown example the server fulfills the client's request and		previously shown example the server fulfills the client's request and
	provides a raw public key into the Certificate payload back to the		provides a raw public key into the Certificate payload back to the
	client (see [2] and [3]). The TLS server, however, demands client		client (see [3]). The TLS server, however, demands client
	authentication and for this reason a Certificate_Request payload is		authentication and therefore a certificate_request is added [4]. The
	added [4], which comes with an indication of the supported		certificate_type payload indicates the TLS server supported
	certificate types by the server, see [5]. The TLS client, who has a		certificate types, see [2], and particularly that the TLS server is
	raw public key pre-provisioned, returns it in the Certificate payload		also able to process raw public keys sent by the client. The TLS
	[7] to the server with the indication about its content [6].		client, who has a raw public key pre-provisioned, returns it in the
			Certificate payload [5] to the server.
	client_hello,		client_hello,
	cert-receive=(RawPublicKey) -> // [1]		certificate_type=(RawPublicKey-Offer, RawPublicKey-Accept) -> // [1]
	<- server_hello,		<- server_hello,
	cert-send=RawPublicKey,// [2]		certificate_type=(RawPublicKey-Offer,
	certificate, // [3]		RawPublicKey-Accept) // [2]
	certificate_request, // [4]		certificate, // [3]
	cert-receive=(RawPublicKey, X.509) // [5]		certificate_request, // [4]
	server_key_exchange,		server_key_exchange,
	server_hello_done		server_hello_done
	cert-send=RawPublicKey, // [6]		certificate, // [5]
	certificate, // [7]		client_key_exchange,
	client_key_exchange,		change_cipher_spec,
	change_cipher_spec,		finished ->
	finished ->
	<- change_cipher_spec,		<- change_cipher_spec,
	finished		finished
	Application Data <-------> Application Data		Application Data <-------> Application Data
	Figure 3: Example with Raw Public Key provided by the TLS Server and		Figure 6: Example with Raw Public Key provided by the TLS Server and
	the Client		the Client
	In our last example we illustrate a combination of raw public key and		In our last example we illustrate a combination of raw public key and
	X.509 usage. The client uses a raw public key for client		X.509 usage. The client uses a raw public key for client
	authentication but the server provides an X.509 certificate. This		authentication but the server provides an X.509 certificate. This
	exchange starts with the client indicating its ability to process		exchange starts with the client indicating its ability to process
	X.509 certificates. The server provides the X.509 certificate using		X.509 certificates provided by the server, and the ability to send
			raw public keys. The server provides the X.509 certificate using
	that format in [3] with the indication present in [2]. For client		that format in [3] with the indication present in [2]. For client
	authentication, however, the server indicates in [5] that it is able		authentication, however, the server indicates in [2] that it is able
	to support raw public keys as well as X.509 certificates. The TLS		to support raw public keys. The TLS client provides a raw public key
	client provides a raw public key in [7] and the indication in [6].		in [5] after receiving and processing the TLS server hello message.
	client_hello,
	cert-receive=(X.509) -> // [1]
	<- server_hello,		client_hello,
	cert-send=X.509,// [2]		certificate_type=(X.509 Receive, RawPublicKey-Offer) -> // [1]
	certificate, // [3]
	certificate_request, // [4]
	cert-receive=(RawPublicKey, X.509) // [5]
	server_key_exchange,
	server_hello_done
	cert-send=RawPublicKey, // [6]		<- server_hello,
	certificate, // [7]		certificate_type=(X.509 Send,
	client_key_exchange,		RawPublicKey-Accept), // [2]
	change_cipher_spec,		certificate, // [3]
	finished ->		certificate_request, // [4]
			server_key_exchange,
			server_hello_done
			certificate, // [5]
			client_key_exchange,
			change_cipher_spec,
			finished ->
	<- change_cipher_spec,		<- change_cipher_spec,
	finished		finished
	Application Data <-------> Application Data		Application Data <-------> Application Data
	Figure 4: Hybrid Certificate Example		Figure 7: Hybrid Certificate Example
	6. Security Considerations		6. Security Considerations
	The transmission of raw public keys, as described in this document,		The transmission of raw public keys, as described in this document,
	provides benefits by lowering the over-the-air transmission overhead		provides benefits by lowering the over-the-air transmission overhead
	since raw public keys are quite naturally smaller than an entire		since raw public keys are quite naturally smaller than an entire
	certificate. There are also advantages from a codesize point of view		certificate. There are also advantages from a codesize point of view
	for parsing and processing these keys. The crytographic procedures		for parsing and processing these keys. The crytographic procedures
	for assocating the public key with the possession of a private key		for assocating the public key with the possession of a private key
	also follows standard procedures.		also follows standard procedures.
	The main security challenge is, however, how to associate the public		The main security challenge is, however, how to associate the public
	key with a specific entity. This information will be needed to make		key with a specific entity. This information will be needed to make
	authorization decisions. Without a secure binding, man-in-the-middle		authorization decisions. Without a secure binding, man-in-the-middle
	attacks may be the consequence. This document assumes that such		attacks may be the consequence. This document assumes that such
	binding can be made out-of-band and we list a few examples in		binding can be made out-of-band and we list a few examples in
	Section 1. DANE [I-D.ietf-dane-protocol] offers one such approach.		Section 1. DANE [RFC6698] offers one such approach. If public keys
	If public keys are obtained using DANE, these public keys are		are obtained using DANE, these public keys are authenticated via
	authenticated via DNSSEC. Pre-configured keys is another out of band		DNSSEC. Pre-configured keys is another out of band method for
	method for authenticating raw public keys. While pre-configured keys		authenticating raw public keys. While pre-configured keys are not
	are not suitable for a generic Web-based e-commerce environment such		suitable for a generic Web-based e-commerce environment such keys are
	keys are a reasonable approach for many smart object deployments		a reasonable approach for many smart object deployments where there
	where there is a close relationship between the software running on		is a close relationship between the software running on the device
	the device and the server-side communication endpoint. Regardless of		and the server-side communication endpoint. Regardless of the chosen
	the chosen mechanism for out-of-band public key validation an		mechanism for out-of-band public key validation an assessment of the
	assessment of the most suitable approach has to be made prior to the		most suitable approach has to be made prior to the start of a
	start of a deployment to ensure the security of the system.		deployment to ensure the security of the system.
	7. IANA Considerations		7. IANA Considerations
	This document defines two new TLS extension, 'cert-send' and 'cert-		This document defines a new TLS extension, "certificate_type",
	receive', and their values need to be added to the TLS ExtensionType		assigned a value of [TBD] from the TLS ExtensionType registry defined
	registry created by RFC 5246 [RFC5246].		in [RFC5246]. This value is used as the extension number for the
			extensions in both the client hello message and the server hello
			message. The new extension type is used for certificate type
			negotiation.
	The values in these new extensions contains an 8-bit CertificateType		The "certificate_type" extension contains an 8-bit CertificateType
	field, for which a new registry, named "Certificate Types", is		field, for which a new registry, named "TLS Certificate Types", is
	established in this document, to be maintained by IANA. The registry		established in this document, to be maintained by IANA. The registry
	is segmented in the following way:		is segmented in the following way:
	1. The value (0) is defined in this document.		1. The values 0 - 3 are defined in Figure 4.
	2. Values from 2 through 223 decimal inclusive are assigned using		2. Values from 3 through 223 decimal inclusive are assigned via IETF
	the 'Specification Required' policy defined in RFC 5226		Consensus [RFC5226].
	[RFC5226].
	3. Values from 224 decimal through 255 decimal inclusive are		3. Values from 224 decimal through 255 decimal inclusive are
	reserved for 'Private Use', see [RFC5226].		reserved for Private Use [RFC5226].
	8. Acknowledgements		8. Acknowledgements
	The feedback from the TLS working group meeting at IETF#81 has		The feedback from the TLS working group meeting at IETF#81 has
	substantially shaped the document and we would like to thank the		substantially shaped the document and we would like to thank the
	meeting participants for their input. The support for hashes of		meeting participants for their input. The support for hashes of
	public keys has been moved to [I-D.ietf-tls-cached-info] after the		public keys has been moved to [I-D.ietf-tls-cached-info] after the
	discussions at the IETF#82 meeting and the feedback from Eric		discussions at the IETF#82 meeting and the feedback from Eric
	Rescorla.		Rescorla.
	We would like to thank the following persons for their review		We would like to thank the following persons for their review
	comments: Martin Rex, Bill Frantz, Zach Shelby, Carsten Bormann,		comments: Martin Rex, Bill Frantz, Zach Shelby, Carsten Bormann,
	Cullen Jennings, Rene Struik, Alper Yegin, Jim Schaad, Paul Hoffman,		Cullen Jennings, Rene Struik, Alper Yegin, Jim Schaad, Paul Hoffman,
	Robert Cragie, Nikos Mavrogiannopoulos, Phil Hunt, John Bradley, and		Robert Cragie, Nikos Mavrogiannopoulos, Phil Hunt, John Bradley,
	James Manger.		Klaus Hartke, Stefan Jucker, and James Manger.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[PKIX] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,		[PKIX] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
	Housley, R., and W. Polk, "Internet X.509 Public Key		Housley, R., and W. Polk, "Internet X.509 Public Key
	Infrastructure Certificate and Certificate Revocation List		Infrastructure Certificate and Certificate Revocation List
	(CRL) Profile", RFC 5280, May 2008.		(CRL) Profile", RFC 5280, May 2008.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	skipping to change at page 11, line 28 ¶		skipping to change at page 13, line 28 ¶
	[Defeating-SSL]		[Defeating-SSL]
	Marlinspike, M., "New Tricks for Defeating SSL in		Marlinspike, M., "New Tricks for Defeating SSL in
	Practice", February 2009, <http://www.blackhat.com/		Practice", February 2009, <http://www.blackhat.com/
	presentations/bh-dc-09/Marlinspike/		presentations/bh-dc-09/Marlinspike/
	BlackHat-DC-09-Marlinspike-Defeating-SSL.pdf>.		BlackHat-DC-09-Marlinspike-Defeating-SSL.pdf>.
	[I-D.ietf-core-coap]		[I-D.ietf-core-coap]
	Shelby, Z., Hartke, K., Bormann, C., and B. Frank,		Shelby, Z., Hartke, K., Bormann, C., and B. Frank,
	"Constrained Application Protocol (CoAP)",		"Constrained Application Protocol (CoAP)",
	draft-ietf-core-coap-10 (work in progress), June 2012.		draft-ietf-core-coap-12 (work in progress), October 2012.
	[I-D.ietf-dane-protocol]
	Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
	of Named Entities (DANE) Transport Layer Security (TLS)
	Protocol: TLSA", draft-ietf-dane-protocol-23 (work in
	progress), June 2012.
	[I-D.ietf-tls-cached-info]		[I-D.ietf-tls-cached-info]
	Santesson, S. and H. Tschofenig, "Transport Layer Security		Santesson, S. and H. Tschofenig, "Transport Layer Security
	(TLS) Cached Information Extension",		(TLS) Cached Information Extension",
	draft-ietf-tls-cached-info-11 (work in progress),		draft-ietf-tls-cached-info-13 (work in progress),
	December 2011.		September 2012.
	[LDAP] Sermersheim, J., "Lightweight Directory Access Protocol		[LDAP] Sermersheim, J., "Lightweight Directory Access Protocol
	(LDAP): The Protocol", RFC 4511, June 2006.		(LDAP): The Protocol", RFC 4511, June 2006.
			[RFC3279] Bassham, L., Polk, W., and R. Housley, "Algorithms and
			Identifiers for the Internet X.509 Public Key
			Infrastructure Certificate and Certificate Revocation List
			(CRL) Profile", RFC 3279, April 2002.
	[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an		[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
	IANA Considerations Section in RFCs", BCP 26, RFC 5226,		IANA Considerations Section in RFCs", BCP 26, RFC 5226,
	May 2008.		May 2008.
	[RFC6091] Mavrogiannopoulos, N. and D. Gillmor, "Using OpenPGP Keys		[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
	for Transport Layer Security (TLS) Authentication",		of Named Entities (DANE) Transport Layer Security (TLS)
	RFC 6091, February 2011.		Protocol: TLSA", RFC 6698, August 2012.
	Authors' Addresses		Authors' Addresses
	Paul Wouters		Paul Wouters (editor)
	Red Hat		Red Hat
	Email: paul@nohats.ca		Email: paul@nohats.ca
			Hannes Tschofenig (editor)
			Nokia Siemens Networks
			Linnoitustie 6
			Espoo 02600
			Finland
			Phone: +358 (50) 4871445
			Email: Hannes.Tschofenig@gmx.net
			URI: http://www.tschofenig.priv.at
	John Gilmore		John Gilmore
	PO Box 170608		PO Box 170608
	San Francisco, California 94117		San Francisco, California 94117
	USA		USA
	Phone: +1 415 221 6524		Phone: +1 415 221 6524
	Email: gnu@toad.com		Email: gnu@toad.com
	URI: https://www.toad.com/		URI: https://www.toad.com/
	Samuel Weiler		Samuel Weiler
	skipping to change at page 12, line 36 ¶		skipping to change at line 541 ¶
	Email: weiler@tislabs.com		Email: weiler@tislabs.com
	Tero Kivinen		Tero Kivinen
	AuthenTec		AuthenTec
	Eerikinkatu 28		Eerikinkatu 28
	HELSINKI FI-00180		HELSINKI FI-00180
	FI		FI
	Email: kivinen@iki.fi		Email: kivinen@iki.fi
	Hannes Tschofenig
	Nokia Siemens Networks
	Linnoitustie 6
	Espoo 02600
	Finland
	Phone: +358 (50) 4871445
	Email: Hannes.Tschofenig@gmx.net
	URI: http://www.tschofenig.priv.at
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