< draft-ietf-httpbis-http2-encryption-01.txt		draft-ietf-httpbis-http2-encryption-02.txt >
	HTTPbis Working Group M. Nottingham		HTTP Working Group M. Nottingham
	Internet-Draft		Internet-Draft
	Intended status: Experimental M. Thomson		Intended status: Experimental M. Thomson
	Expires: June 18, 2015 Mozilla		Expires: December 17, 2015 Mozilla
	December 15, 2014		June 15, 2015
	Opportunistic Security for HTTP		Opportunistic Security for HTTP
	draft-ietf-httpbis-http2-encryption-01		draft-ietf-httpbis-http2-encryption-02
	Abstract		Abstract
	This document describes how "http" URIs can be accessed using		This document describes how "http" URIs can be accessed using
	Transport Layer Security (TLS) to mitigate pervasive monitoring		Transport Layer Security (TLS) to mitigate pervasive monitoring
	attacks.		attacks.
	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
	skipping to change at page 1, line 33 ¶		skipping to change at page 1, line 33 ¶
	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 June 18, 2015.		This Internet-Draft will expire on December 17, 2015.
	Copyright Notice		Copyright Notice
	Copyright (c) 2014 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
	skipping to change at page 2, line 15 ¶		skipping to change at page 2, line 15 ¶
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Goals and Non-Goals . . . . . . . . . . . . . . . . . . . 3		1.1. Goals and Non-Goals . . . . . . . . . . . . . . . . . . . 3
	1.2. Notational Conventions . . . . . . . . . . . . . . . . . 3		1.2. Notational Conventions . . . . . . . . . . . . . . . . . 3
	2. Using HTTP URIs over TLS . . . . . . . . . . . . . . . . . . 3		2. Using HTTP URIs over TLS . . . . . . . . . . . . . . . . . . 3
	3. Server Authentication . . . . . . . . . . . . . . . . . . . . 4		3. Server Authentication . . . . . . . . . . . . . . . . . . . . 4
	4. Interaction with "https" URIs . . . . . . . . . . . . . . . . 4		4. Interaction with "https" URIs . . . . . . . . . . . . . . . . 4
	5. Requiring Use of TLS . . . . . . . . . . . . . . . . . . . . 5		5. Requiring Use of TLS . . . . . . . . . . . . . . . . . . . . 5
	5.1. The HTTP-TLS Header Field . . . . . . . . . . . . . . . . 5		5.1. The HTTP-TLS Header Field . . . . . . . . . . . . . . . . 5
	5.2. Operational Considerations . . . . . . . . . . . . . . . 6		5.2. Operational Considerations . . . . . . . . . . . . . . . 7
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 7		6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	6.1. Security Indicators . . . . . . . . . . . . . . . . . . . 7		6.1. Security Indicators . . . . . . . . . . . . . . . . . . . 7
	6.2. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 7		6.2. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 7
	6.3. Privacy Considerations . . . . . . . . . . . . . . . . . 7		6.3. Privacy Considerations . . . . . . . . . . . . . . . . . 8
	6.4. Confusion Regarding Request Scheme . . . . . . . . . . . 8		6.4. Confusion Regarding Request Scheme . . . . . . . . . . . 8
	7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8		7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
	7.1. Normative References . . . . . . . . . . . . . . . . . . 8		7.1. Normative References . . . . . . . . . . . . . . . . . . 8
	7.2. Informative References . . . . . . . . . . . . . . . . . 9		7.2. Informative References . . . . . . . . . . . . . . . . . 9
	Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 9		Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 9
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
	1. Introduction		1. Introduction
	This document describes a use of HTTP Alternative Services		This document describes a use of HTTP Alternative Services
	[I-D.ietf-httpbis-alt-svc] to decouple the URI scheme from the use		[I-D.ietf-httpbis-alt-svc] to decouple the URI scheme from the use
	and configuration of underlying encryption, allowing a "http" URI to		and configuration of underlying encryption, allowing a "http" URI to
	be accessed using TLS [RFC5246] opportunistically.		be accessed using TLS [RFC5246] opportunistically.
	Currently, "https" URIs require acquiring and configuring a valid		Serving "https" URIs require acquiring and configuring a valid
	certificate, which means that some deployments find supporting TLS		certificate, which means that some deployments find supporting TLS
	difficult. Therefore, this document describes a usage model whereby		difficult. This document describes a usage model whereby sites can
	sites can serve "http" URIs over TLS without being required to		serve "http" URIs over TLS without being required to support strong
	support strong server authentication.		server authentication.
	Opportunistic Security [I-D.dukhovni-opportunistic-security] does not		Opportunistic Security [RFC7435] does not provide the same guarantees
	provide the same guarantees as using TLS with "https" URIs; it is		as using TLS with "https" URIs; it is vulnerable to active attacks,
	vulnerable to active attacks, and does not change the security		and does not change the security context of the connection.
	context of the connection. Normally, users will not be able to tell		Normally, users will not be able to tell that it is in use (i.e.,
	that it is in use (i.e., there will be no "lock icon").		there will be no "lock icon").
	By its nature, this technique is vulnerable to active attacks. A		By its nature, this technique is vulnerable to active attacks. A
	mechanism for partially mitigating them is described in Section 5.		mechanism for partially mitigating them is described in Section 5.
	It does not offer the same level of protection as afforded to "https"
	URIs, but increases the likelihood that an active attack be detected.
	1.1. Goals and Non-Goals		1.1. Goals and Non-Goals
	The immediate goal is to make the use of HTTP more robust in the face		The immediate goal is to make the use of HTTP more robust in the face
	of pervasive passive monitoring [RFC7258].		of pervasive passive monitoring [RFC7258].
	A secondary goal is to limit the potential for active attacks. It is		A secondary goal is to limit the potential for active attacks. It is
	not intended to offer the same level of protection as afforded to		not intended to offer the same level of protection as afforded to
	"https" URIs, but instead to increase the likelihood that an active		"https" URIs, but instead to increase the likelihood that an active
	attack can be detected.		attack can be detected.
	A final (but significant) goal is to provide for ease of		A final (but significant) goal is to provide for ease of
	implementation, deployment and operation. This mechanism should have		implementation, deployment and operation. This mechanism is expected
	a minimal impact upon performance, and should not require extensive		to have a minimal impact upon performance, and a trivial
	administrative effort to configure.		administrative effort to configure.
	1.2. Notational Conventions		1.2. Notational Conventions
	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. Using HTTP URIs over TLS		2. Using HTTP URIs over TLS
	An origin server that supports the resolution of "http" URIs can		An origin server that supports the resolution of "http" URIs can
	indicate support for this specification by providing an alternative		indicate support for this specification by providing an alternative
	service advertisement [I-D.ietf-httpbis-alt-svc] for a protocol		service advertisement [I-D.ietf-httpbis-alt-svc] for a protocol
	identifier that uses TLS, such as "h2" [I-D.ietf-httpbis-http2].		identifier that uses TLS, such as "h2" [RFC7540].
	A client that receives such an advertisement MAY make future requests		A client that receives such an advertisement MAY make future requests
	intended for the associated origin ([RFC6454]) to the identified		intended for the associated origin ([RFC6454]) to the identified
	service (as specified by [I-D.ietf-httpbis-alt-svc]).		service (as specified by [I-D.ietf-httpbis-alt-svc]).
	A client that places the importance of protection against passive		A client that places the importance of protection against passive
	attacks over performance might choose to withhold requests until an		attacks over performance might choose to withhold requests until an
	encrypted connection is available. However, if such a connection		encrypted connection is available. However, if such a connection
	cannot be successfully established, the client MAY resume its use of		cannot be successfully established, the client can resume its use of
	the cleartext connection.		the cleartext connection.
	A client can also explicitly probe for an alternative service		A client can also explicitly probe for an alternative service
	advertisement by sending a request that bears little or no sensitive		advertisement by sending a request that bears little or no sensitive
	information, such as one with the OPTIONS method. Likewise, clients		information, such as one with the OPTIONS method. Likewise, clients
	with existing alternative services information could make such a		with existing alternative services information could make such a
	request before they expire, in order minimize the delays that might		request before they expire, in order minimize the delays that might
	be incurred.		be incurred.
	3. Server Authentication		3. Server Authentication
	skipping to change at page 4, line 20 ¶		skipping to change at page 4, line 20 ¶
	operational challenges. For these reasons, server authentication is		operational challenges. For these reasons, server authentication is
	not mandatory for "http" URIs when using the mechanism described in		not mandatory for "http" URIs when using the mechanism described in
	this specification.		this specification.
	When connecting to an alternative service for an "http" URI, clients		When connecting to an alternative service for an "http" URI, clients
	are not required to perform the server authentication procedure		are not required to perform the server authentication procedure
	described in Section 3.1 of [RFC2818]. The server certificate, if		described in Section 3.1 of [RFC2818]. The server certificate, if
	one is proffered by the alternative service, is not necessarily		one is proffered by the alternative service, is not necessarily
	checked for validity, expiration, issuance by a trusted certificate		checked for validity, expiration, issuance by a trusted certificate
	authority or matched against the name in the URI. Therefore, the		authority or matched against the name in the URI. Therefore, the
	alternative service MAY provide any certificate, or even select TLS		alternative service can provide any certificate, or even select TLS
	cipher suites that do not include authentication.		cipher suites that do not include authentication.
	A client MAY perform additional checks on the offered certificate if		A client MAY perform additional checks on the offered certificate if
	the server does not select an unauthenticated TLS cipher suite. This		the server does not select an unauthenticated TLS cipher suite. This
	document doesn't define any such checks, though clients could be		document doesn't define any such checks, though clients could be
	configured with a policy that defines what is acceptable.		configured with a policy that defines what is acceptable.
	As stipulated by [I-D.ietf-httpbis-alt-svc], clients MUST NOT use		As stipulated by [I-D.ietf-httpbis-alt-svc], clients MUST NOT use
	alternative services with a host other than the origin's, unless the		alternative services with a host other than the origin's, unless the
	alternative service itself is strongly authenticated (as the origin's		alternative service itself is strongly authenticated (as the origin's
	host); for example, using TLS with a certificate that validates as		host); for example, using TLS with a certificate that validates as
	per [RFC2818].		per [RFC2818].
	4. Interaction with "https" URIs		4. Interaction with "https" URIs
	When using alternative services, both "http" and "https" URIs might		When using alternative services, requests for resources identified by
	use the same connection, because HTTP/2 permits requests for multiple		both "http" and "https" URIs might use the same connection, because
	origins on the same connection.		HTTP/2 permits requests for multiple origins on the same connection.
	Since "https" URIs rely on server authentication, a connection that		Since "https" URIs rely on server authentication, a connection that
	is initially created for "http" URIs without authenticating the		is initially created for "http" URIs without authenticating the
	server cannot be used for "https" URIs until the server certificate		server cannot be used for "https" URIs until the server certificate
	is successfully authenticated. Section 3.1 of [RFC2818] describes		is successfully authenticated. Section 3.1 of [RFC2818] describes
	the basic mechanism, though the authentication considerations in		the basic mechanism, though the authentication considerations in
	[I-D.ietf-httpbis-alt-svc] also apply.		[I-D.ietf-httpbis-alt-svc] also apply.
	Connections that are established without any means of server		Connections that are established without any means of server
	authentication (for instance, the purely anonymous TLS cipher		authentication (for instance, the purely anonymous TLS cipher
	suites), cannot be used for "https" URIs.		suites), cannot be used for "https" URIs.
	5. Requiring Use of TLS		5. Requiring Use of TLS
	Editors' Note: this is a very rough take on an approach that would		Editors' Note: this is a very rough take on an approach that would
	provide a limited form of protection against downgrade attack. It's		provide a limited form of protection against downgrade attack. It's
	unclear at this point whether the additional effort (and modest		unclear at this point whether the additional effort (and modest
	operational cost) is worthwhile.		operational cost) is worthwhile.
	The mechanism described in this specification is trival to mount an		The mechanism described in this specification is trivial to mount an
	active attack against, for two reasons:		active attack against, for two reasons:
	o A client that doesn't perform authentication an easy victim of		o A client that doesn't perform authentication is an easy victim of
	server impersonation, through man-in-the-middle attacks.		server impersonation, through man-in-the-middle attacks.
	o A client that is willing to use cleartext to resolve the resource		o A client that is willing to use HTTP over cleartext to resolve the
	will do so if access to any TLS-enabled alternative services is		resource will do so if access to any TLS-enabled alternative
	blocked at the network layer.		services is blocked at the network layer.
	Given that the primary goal of this specification is to prevent		Given that the primary goal of this specification is to prevent
	passive attacks, these are not critical failings (especially		passive attacks, these are not critical failings (especially
	considering the alternative - HTTP over cleartext). However, a		considering the alternative - HTTP over cleartext). However, a
	modest form of protection against active attacks can be provided for		modest form of protection against active attacks can be provided for
	clients on subsequent connections.		clients on subsequent connections.
	When an alternative service is able to commit to providing service		When an alternative service is able to commit to providing service
	for a particular origin over TLS for a bounded period of time,		for a particular origin over TLS for a bounded period of time,
	clients can choose to rely upon its avilability, failing when it		clients can choose to rely upon its availability, failing when it
	cannot be contacted. Effectively, this makes the choice to use a		cannot be contacted. Effectively, this makes the choice to use a
	secured protocol "sticky" in the client.		secured protocol "sticky" in the client.
	5.1. The HTTP-TLS Header Field		5.1. The HTTP-TLS Header Field
	A alternative service can make this commitment by sending a "HTTP-		A alternative service can make this commitment by sending a "HTTP-
	TLS" header field:		TLS" header field, described here using the '#' ABNF extension
			defined in Section 7 of [RFC7230]:
	HTTP-TLS = 1#parameter		HTTP-TLS = 1#parameter
	When it appears in a HTTP response from a strongly authenticated		When it appears in a HTTP response from a strongly authenticated
	alternative service, this header field indicates that the		alternative service, this header field indicates that the
	availability of the origin through TLS-protected alternative services		availability of the origin through TLS-protected alternative services
	is "sticky", and that the client MUST NOT fall back to cleartext		is "sticky", and that the client MUST NOT fall back to cleartext
	protocols while this information is considered fresh.		protocols while this information is considered fresh.
	For example:		For example:
	GET /index.html HTTP/1.1		GET /index.html HTTP/1.1
	Host: example.com		Host: example.com
	HTTP/1.1 200 OK		HTTP/1.1 200 OK
	Content-Type: text/html		Content-Type: text/html
	Cache-Control: 600		Cache-Control: max-age=600
	Age: 30		Age: 30
	Date: Thu, 1 May 2014 16:20:09 GMT		Date: Thu, 1 May 2014 16:20:09 GMT
	HTTP-TLS: ma=3600		HTTP-TLS: ma=3600
	This header field creates a commitment from the origin [RFC6454] of		This header field creates a commitment from the origin [RFC6454] of
	the associated resource (in the example, "http://example.com"). For		the associated resource (in the example, "http://example.com"). For
	the duration of the commitment, clients SHOULD strongly authenticate		the duration of the commitment, clients SHOULD strongly authenticate
	the server for all subsequent requests made to that origin, though		the server for all subsequent requests made to that origin, though
	this creates some risks for clients Section 5.2.		this creates some risks for clients (see Section 5.2).
	Authentication for HTTP over TLS is described in Section 3.1 of		Authentication for HTTP over TLS is described in Section 3.1 of
	[RFC2818], noting the additional requirements in		[RFC2818], noting the additional requirements in Section 2.1 of
	[I-D.ietf-httpbis-alt-svc]. The header field MUST be ignored if		[I-D.ietf-httpbis-alt-svc]. The header field MUST be ignored if
	strong authentication fails; otherwise, an attacker could create a		strong authentication fails; otherwise, an attacker could create a
	persistent denial of service by falsifying a commitment.		persistent denial of service by falsifying a commitment.
	The commitment to use authenticated TLS persists for a period		The commitment to use authenticated TLS persists for a period
	determined by the value of the "ma" parameter. See Section 4.2.3 of		determined by the value of the "ma" parameter. See Section 4.2.3 of
	[RFC7234] for details of determining response age.		[RFC7234] for details of determining response age.
	ma-parameter = delta-seconds		ma-parameter = delta-seconds
	The commitment made by the "HTTP-TLS" header field applies only to		The commitment made by the "HTTP-TLS" header field applies only to
	the origin of the resource that generates the "HTTP-TLS" header		the origin of the resource that generates the "HTTP-TLS" header
	field. Requests for an origin that has a persisted, unexpired value		field.
	for "HTTP-TLS" MUST fail if they cannot be made over an authenticated
	TLS connection.		Requests for an origin that has a persisted, unexpired value for
			"HTTP-TLS" MUST fail if they cannot be made over an authenticated TLS
			connection.
	Note that the commitment is not bound to a particular alternative		Note that the commitment is not bound to a particular alternative
	service. Clients SHOULD use alternative services that they become		service. Clients SHOULD use alternative services that they become
	aware of. However, clients MUST NOT use an unauthenticated		aware of. However, clients MUST NOT use an unauthenticated
	alternative service for an origin with this commitment. Where there		alternative service for an origin with this commitment. Where there
	is an active commitment, clients MAY instead ignore advertisements		is an active commitment, clients MAY instead ignore advertisements
	for unsecured alternatives services.		for unsecured alternatives services.
	5.2. Operational Considerations		5.2. Operational Considerations
	To avoid situations where a persisted value of "HTTP-TLS" causes a		To avoid situations where a persisted value of "HTTP-TLS" causes a
	client to be unable to contact a site, clients SHOULD limit the time		client to be unable to contact a site, clients SHOULD limit the time
	that a value is persisted for a given origin. A lower limit might be		that a value is persisted for a given origin. A lower limit might be
	appropriate for initial observations of "HTTP-TLS"; the certainty		appropriate for initial observations of "HTTP-TLS"; the certainty
	that a site has set a correct value - and the corresponding limit on		that a site has set a correct value - and the corresponding limit on
	persistence - can increase as the value is seen more over time.		persistence - can increase as the value is seen more over time.
	Once a server has indicated that it will support authenticated TLS, a		Once a server has indicated that it will support authenticated TLS, a
	client MAY use key pinning [I-D.ietf-websec-key-pinning] or any other		client MAY use key pinning [RFC7469] or any other mechanism that
	mechanism that would otherwise be restricted to use with "https"		would otherwise be restricted to use with "https" URIs, provided that
	URIs, provided that the mechanism can be restricted to a single HTTP		the mechanism can be restricted to a single HTTP origin.
	origin.
	6. Security Considerations		6. Security Considerations
	6.1. Security Indicators		6.1. Security Indicators
	User Agents MUST NOT provide any special security indicia when an		User Agents MUST NOT provide any special security indicia when an
	"http" resource is acquired using TLS. In particular, indicators		"http" resource is acquired using TLS. In particular, indicators
	that might suggest the same level of security as "https" MUST NOT be		that might suggest the same level of security as "https" MUST NOT be
	used (e.g., using a "lock device").		used (e.g., using a "lock device").
	skipping to change at page 8, line 13 ¶		skipping to change at page 8, line 21 ¶
	based state (i.e., cookies).		based state (i.e., cookies).
	6.4. Confusion Regarding Request Scheme		6.4. Confusion Regarding Request Scheme
	Many existing HTTP/1.1 implementations use the presence or absence of		Many existing HTTP/1.1 implementations use the presence or absence of
	TLS in the stack to determine whether requests are for "http" or		TLS in the stack to determine whether requests are for "http" or
	"https" resources. This is necessary in many cases because the most		"https" resources. This is necessary in many cases because the most
	common form of an HTTP/1.1 request does not carry an explicit		common form of an HTTP/1.1 request does not carry an explicit
	indication of the URI scheme.		indication of the URI scheme.
	HTTP/1.1 MUST NOT be sent over HTTP/1.1 or earlier versions of the		HTTP/1.1 MUST NOT be used for opportunistically secured requests.
	protocol. Opportunistically secured HTTP requests MUST include an
	explicit scheme identifier.
	7. References		7. References
	7.1. Normative References		7.1. Normative References
	[I-D.ietf-httpbis-alt-svc]		[I-D.ietf-httpbis-alt-svc]
	Nottingham, M., McManus, P., and J. Reschke, "HTTP		mnot, m., McManus, P., and J. Reschke, "HTTP Alternative
	Alternative Services", draft-ietf-httpbis-alt-svc-05 (work		Services", draft-ietf-httpbis-alt-svc-07 (work in
	in progress), December 2014.		progress), May 2015.
	[I-D.ietf-httpbis-http2]
	Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer
	Protocol version 2", draft-ietf-httpbis-http2-16 (work in
	progress), November 2014.
	[I-D.ietf-websec-key-pinning]
	Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning
	Extension for HTTP", draft-ietf-websec-key-pinning-21
	(work in progress), October 2014.
	[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, DOI 10.17487/
			RFC2119, March 1997,
			<http://www.rfc-editor.org/info/rfc2119>.
	[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.		[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/
			RFC2818, May 2000,
			<http://www.rfc-editor.org/info/rfc2818>.
	[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security		[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
	(TLS) Protocol Version 1.2", RFC 5246, August 2008.		(TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/
			RFC5246, August 2008,
			<http://www.rfc-editor.org/info/rfc5246>.
	[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, December		[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, DOI 10
	2011.		.17487/RFC6454, December 2011,
			<http://www.rfc-editor.org/info/rfc6454>.
			[RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
			(HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10
			.17487/RFC7230, June 2014,
			<http://www.rfc-editor.org/info/rfc7230>.
	[RFC7234] Fielding, R., Nottingham, M., and J. Reschke, "Hypertext		[RFC7234] Fielding, R., Nottingham, M., and J. Reschke, "Hypertext
	Transfer Protocol (HTTP/1.1): Caching", RFC 7234, June		Transfer Protocol (HTTP/1.1): Caching", RFC 7234, DOI 10
	2014.		.17487/RFC7234, June 2014,
			<http://www.rfc-editor.org/info/rfc7234>.
	7.2. Informative References		[RFC7469] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning
			Extension for HTTP", RFC 7469, DOI 10.17487/RFC7469, April
			2015, <http://www.rfc-editor.org/info/rfc7469>.
	[I-D.dukhovni-opportunistic-security]		[RFC7540] Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer
	Dukhovni, V., "Opportunistic Security: Some Protection		Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/
	Most of the Time", draft-dukhovni-opportunistic-		RFC7540, May 2015,
	security-06 (work in progress), November 2014.		<http://www.rfc-editor.org/info/rfc7540>.
			7.2. Informative References
	[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an		[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
	Attack", BCP 188, RFC 7258, May 2014.		Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
			2014, <http://www.rfc-editor.org/info/rfc7258>.
			[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection
			Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
			December 2014, <http://www.rfc-editor.org/info/rfc7435>.
	Appendix A. Acknowledgements		Appendix A. Acknowledgements
	Thanks to Patrick McManus, Eliot Lear, Stephen Farrell, Guy Podjarny,		Thanks to Patrick McManus, Eliot Lear, Stephen Farrell, Guy Podjarny,
	Stephen Ludin, Erik Nygren, Paul Hoffman, Adam Langley, Eric Rescorla		Stephen Ludin, Erik Nygren, Paul Hoffman, Adam Langley, Eric Rescorla
	and Richard Barnes for their feedback and suggestions.		and Richard Barnes for their feedback and suggestions.
	Authors' Addresses		Authors' Addresses
	Mark Nottingham		Mark Nottingham
End of changes. 36 change blocks.
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