< draft-ietf-tokbind-ttrp-04.txt		draft-ietf-tokbind-ttrp-05.txt >
	Internet Engineering Task Force B. Campbell		Internet Engineering Task Force B. Campbell
	Internet-Draft Ping Identity		Internet-Draft Ping Identity
	Intended status: Standards Track June 6, 2018		Intended status: Standards Track June 21, 2018
	Expires: December 8, 2018		Expires: December 23, 2018
	HTTPS Token Binding with TLS Terminating Reverse Proxies		HTTPS Token Binding with TLS Terminating Reverse Proxies
	draft-ietf-tokbind-ttrp-04		draft-ietf-tokbind-ttrp-05
	Abstract		Abstract
	This document defines HTTP header fields that enable a TLS		This document defines HTTP header fields that enable a TLS
	terminating reverse proxy to convey information to a backend server		terminating reverse proxy to convey information to a backend server
	about the validated Token Binding Message received from a client,		about the validated Token Binding Message received from a client,
	which enables that backend server to bind, or verify the binding of,		which enables that backend server to bind, or verify the binding of,
	cookies and other security tokens to the client's Token Binding key.		cookies and other security tokens to the client's Token Binding key.
	This facilitates the reverse proxy and backend server functioning		This facilitates the reverse proxy and backend server functioning
	together as though they are a single logical server side deployment		together as though they are a single logical server side deployment
	skipping to change at page 1, line 37 ¶		skipping to change at page 1, line 37 ¶
	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-
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	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
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	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 December 8, 2018.		This Internet-Draft will expire on December 23, 2018.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2018 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 . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Requirements Notation and Conventions . . . . . . . . . . 3		1.1. Requirements Notation and Conventions . . . . . . . . . . 3
	2. HTTP Header Fields and Processing Rules . . . . . . . . . . . 3		2. HTTP Header Fields and Processing Rules . . . . . . . . . . . 4
	2.1. Encoding . . . . . . . . . . . . . . . . . . . . . . . . 4		2.1. Encoding . . . . . . . . . . . . . . . . . . . . . . . . 4
	2.1.1. Token Binding ID . . . . . . . . . . . . . . . . . . 4		2.1.1. Token Binding ID . . . . . . . . . . . . . . . . . . 4
	2.1.2. Token Binding Type . . . . . . . . . . . . . . . . . 4		2.1.2. Token Binding Type . . . . . . . . . . . . . . . . . 4
	2.2. Token Binding ID HTTP Header Fields . . . . . . . . . . . 4		2.2. Token Binding ID HTTP Header Fields . . . . . . . . . . . 4
	2.3. Processing Rules . . . . . . . . . . . . . . . . . . . . 5		2.3. Processing Rules . . . . . . . . . . . . . . . . . . . . 5
	2.4. Examples . . . . . . . . . . . . . . . . . . . . . . . . 6		2.4. Examples . . . . . . . . . . . . . . . . . . . . . . . . 6
	2.4.1. Provided Token Binding ID . . . . . . . . . . . . . . 6		2.4.1. Provided Token Binding ID . . . . . . . . . . . . . . 6
	2.4.2. Provided and Referred Token Binding IDs . . . . . . . 7		2.4.2. Provided and Referred Token Binding IDs . . . . . . . 7
	2.4.3. Provided and Other Token Binding IDs . . . . . . . . 8		2.4.3. Provided and Other Token Binding IDs . . . . . . . . 8
	3. Security Considerations . . . . . . . . . . . . . . . . . . . 9		3. Security Considerations . . . . . . . . . . . . . . . . . . . 8
	4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9		3.1. HTTP Headers . . . . . . . . . . . . . . . . . . . . . . 9
			3.2. TLS Versions and Best Practices . . . . . . . . . . . . . 9
			4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
	4.1. HTTP Message Header Field Names Registration . . . . . . 10		4.1. HTTP Message Header Field Names Registration . . . . . . 10
	5. References . . . . . . . . . . . . . . . . . . . . . . . . . 10		5. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
	5.1. Normative References . . . . . . . . . . . . . . . . . . 10		5.1. Normative References . . . . . . . . . . . . . . . . . . 10
	5.2. Informative References . . . . . . . . . . . . . . . . . 11		5.2. Informative References . . . . . . . . . . . . . . . . . 11
	Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11		Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 12
	Appendix B. Document History . . . . . . . . . . . . . . . . . . 12		Appendix B. Document History . . . . . . . . . . . . . . . . . . 12
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14
	1. Introduction		1. Introduction
	Token Binding over HTTP [I-D.ietf-tokbind-https] provides a mechanism		Token Binding over HTTP [I-D.ietf-tokbind-https] provides a mechanism
	that enables HTTP servers to cryptographically bind cookies and other		that enables HTTP servers to cryptographically bind cookies and other
	security tokens to a key held by the browser or other HTTP client,		security tokens to a key generated by the client. When the use of
	possession of which is proven on the TLS [RFC5246] connections over		Token Binding is negotiated in the TLS [RFC5246] handshake
	which the tokens are used. When Token Binding is negotiated in the		[I-D.ietf-tokbind-negotiation] the client sends an encoded Token
	TLS handshake [I-D.ietf-tokbind-negotiation] the client sends an		Binding Message [I-D.ietf-tokbind-protocol] as a header in each HTTP
	encoded Token Binding Message [I-D.ietf-tokbind-protocol] as a header		request, which proves possession of one or more private keys held by
	in each HTTP request, which proves possession of one or more private		the client. The public portion of the keys are represented in the
	keys held by the client. The public portion of the keys are		Token Binding IDs of the Token Binding Message and for each one there
	represented in the Token Binding IDs of the Token Binding Message and		is a signature over some data, which includes the exported keying
	for each one there is a signature over some data, which includes the		material [RFC5705] of the TLS connection. An HTTP server issuing
	exported keying material [RFC5705] of the TLS connection. An HTTP		cookies or other security tokens can associate them with the Token
	server issuing cookies or other security tokens can associate them		Binding ID, which ensures those tokens cannot be used successfully
	with the Token Binding ID, which ensures those tokens cannot be used		over a different TLS connection or by a different client than the one
	successfully over a different TLS connection or by a different client		to which they were issued.
	than the one to which they were issued.
	A fairly common deployment architecture for HTTPS applications is to		A fairly common deployment architecture for HTTPS applications is to
	have the backend HTTP application servers sit behind a reverse proxy		have the backend HTTP application servers sit behind a reverse proxy
	that terminates TLS. The proxy is accessible to the internet and		that terminates TLS connections from clients. The proxy is
	dispatches client requests to the appropriate backend server within a		accessible to the internet and dispatches client requests to the
	private or protected network. The backend servers are not directly		appropriate backend server within a private or protected network.
	accessible outside the private network and are only reachable through		The backend servers are not directly accessible by clients and are
	the reverse proxy. The details of such deployments are typically		only reachable through the reverse proxy. The details of such
	opaque to clients who make requests to the proxy server and see		deployments are typically opaque to clients who make requests to the
	responses as though they originated from the proxy server itself.		proxy server and see responses as though they originated from the
	TLS connections for HTTPS are established between each client and the		proxy server itself. Although HTTPS is also usually employed between
	reverse proxy server.		the proxy and the backend server, the TLS connection that the client
			establishes for HTTPS is between itself and the reverse proxy server.
	Token Binding facilitates a binding of security tokens to a key held		Token Binding facilitates a binding of security tokens to a key held
	by the client by way of the TLS connection between that client and		by the client by way of the TLS connection between that client and
	the server. In a deployment where TLS is terminated by a reverse		the server. In a deployment where TLS is terminated by a reverse
	proxy, however, the TLS connection is between the client and the		proxy, however, the TLS connection is between the client and the
	proxy while the backend server is likely the system that will issue		proxy while the backend server is likely the system that will issue
	and validate cookies or other security tokens. Additional steps are		and validate cookies or other security tokens. Additional steps are
	therefore needed to enable the use of Token Binding in such		therefore needed to enable the use of Token Binding in such
	deployment architectures. In the absence of a standardized approach,		deployment architectures. In the absence of a standardized approach,
	different implementations will address it differently, which will		different implementations will address it differently, which will
	make interoperability between such implementations difficult or		make interoperability between such implementations difficult or
	impossible without complex configurations or custom integrations.		impossible without complex configurations or custom integrations.
	This document standardizes HTTP header field names that a TLS		This document standardizes HTTP header field names that a TLS
	terminating reverse proxy (TTRP) adds to requests that it sends to		terminating reverse proxy (TTRP) adds to requests that it sends to
	the backend servers. The headers contain information from the		the backend servers. The headers contain information from the
	validated Token Binding Message sent by the client to the proxy, thus		validated Token Binding Message sent by the client to the proxy, thus
	enabling the backend server to bind, or verify the binding of,		enabling the backend server to bind, or verify the binding of,
	cookies and other security tokens to the client's Token Binding key.		cookies and other security tokens to the client's Token Binding key.
	The usage of the headers, both the reverse proxy adding it and the		The usage of the headers, both the TTRP adding the headers and the
	application server using them to bind cookies or other tokens, are to		backend application server using the headers to bind cookies or other
	be configuration options of the respective systems as they will not		tokens, are to be configuration options of the respective systems as
	always be applicable.		they will not always be applicable.
	1.1. Requirements Notation and Conventions		1.1. Requirements Notation and 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", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	2. HTTP Header Fields and Processing Rules		2. HTTP Header Fields and Processing Rules
	skipping to change at page 4, line 30 ¶		skipping to change at page 4, line 33 ¶
	EncodedTokenBindingID = *( DIGIT / ALPHA / "-" / "_" )		EncodedTokenBindingID = *( DIGIT / ALPHA / "-" / "_" )
	DIGIT = <Defined in Section B.1 of [RFC5234]>		DIGIT = <Defined in Section B.1 of [RFC5234]>
	ALPHA = <Defined in Section B.1 of [RFC5234]>		ALPHA = <Defined in Section B.1 of [RFC5234]>
	Figure 1: Encoded Token Binding ID ABNF		Figure 1: Encoded Token Binding ID ABNF
	2.1.2. Token Binding Type		2.1.2. Token Binding Type
	A Token Binding type value (a single byte) can be represented as an		A Token Binding type value (a single byte) can be represented as an
	"EncodedTokenBindingType", which is a case-insensitive hex (Section 8		"EncodedTokenBindingType", which is a case-insensitive hex encoding
	of [RFC4648]) encoding. The ABNF definition is shown in Figure 2		(Section 8 of [RFC4648]). The ABNF definition is shown in Figure 2
	below.		below.
	EncodedTokenBindingType = 1*2HEXDIG		EncodedTokenBindingType = 1*2HEXDIG
	HEXDIG = <Defined in Section B.1 of [RFC5234]>		HEXDIG = <Defined in Section B.1 of [RFC5234]>
	Figure 2: Encoded Token Binding Type ABNF		Figure 2: Encoded Token Binding Type ABNF
	2.2. Token Binding ID HTTP Header Fields		2.2. Token Binding ID HTTP Header Fields
	skipping to change at page 5, line 12 ¶		skipping to change at page 5, line 14 ¶
	Sec-Provided-Token-Binding-ID		Sec-Provided-Token-Binding-ID
	The Token Binding ID of the provided Token Binding represented as		The Token Binding ID of the provided Token Binding represented as
	an "EncodedTokenBindingID".		an "EncodedTokenBindingID".
	Sec-Referred-Token-Binding-ID		Sec-Referred-Token-Binding-ID
	The Token Binding ID of the referred Token Binding represented as		The Token Binding ID of the referred Token Binding represented as
	an "EncodedTokenBindingID".		an "EncodedTokenBindingID".
	Sec-Other-Token-Binding-ID		Sec-Other-Token-Binding-ID
	Additional Token Bindings, other than provided and referred, that		Additional Token Bindings that are sent by the client and
	are sent by the client and validated by the TTRP are represented		validated by the TTRP are represented as a comma-separated list of
	as a comma-separated list of the concatenation of the		the concatenation of the "EncodedTokenBindingType", a period (".")
	"EncodedTokenBindingType", a period (".") character, and the		character, and the "EncodedTokenBindingID" of each.
	"EncodedTokenBindingID" of each.
	Both "Sec-Provided-Token-Binding-ID" and "Sec-Referred-Token-Binding-		Both "Sec-Provided-Token-Binding-ID" and "Sec-Referred-Token-Binding-
	ID" are single HTTP header field-valued as defined in Section 3.2 of		ID" are single HTTP header field-valued as defined in Section 3.2 of
	[RFC7230], which MUST NOT have a list of values or occur multiple		[RFC7230], which MUST NOT have a list of values or occur multiple
	times in a request.		times in a request.
	All header fields defined herein are only for use in HTTP requests		All header fields defined herein are only for use in HTTP requests
	and MUST NOT to be used in HTTP responses.		and MUST NOT to be used in HTTP responses.
	2.3. Processing Rules		2.3. Processing Rules
	This section defines the applicable processing rules for a TLS		This section defines the applicable processing rules for a TLS
	terminating reverse proxy (TTRP) and backend server(s) to provide		terminating reverse proxy (TTRP) and backend server(s) to provide
	server side support of Token Binding over HTTP		server side support of Token Binding over HTTP
	[I-D.ietf-tokbind-https] using the HTTP headers described in		[I-D.ietf-tokbind-https] using the HTTP headers described in
	Section 2.2. Use of the technique is to be a configuration or		Section 2.2. Use of the technique is to be a configuration or
	deployment option and the processing rules described herein are for		deployment option and the processing rules described herein are for
	servers operating with that option enabled.		servers operating with that option enabled.
	A TTRP negotiates the use of Token Binding with the client per		A TTRP negotiates the use of Token Binding with the client, such as
	[I-D.ietf-tokbind-negotiation] and validates the Token Binding		is described in [I-D.ietf-tokbind-negotiation] and validates the
	Message as defined in The Token Binding Protocol		Token Binding Message as defined in The Token Binding Protocol
	[I-D.ietf-tokbind-protocol] and Token Binding over HTTP		[I-D.ietf-tokbind-protocol] and Token Binding over HTTP
	[I-D.ietf-tokbind-https] for each HTTP request on the underlying TLS		[I-D.ietf-tokbind-https] for each HTTP request on the underlying TLS
	connection. Requests with a valid Token Binding Message (and meeting		connection. Requests with a valid Token Binding Message (and meeting
	any other authorization or policy requirements of the TTRP) are		any other authorization or policy requirements of the TTRP) are
	dispatched to the backend server with the following modifications.		dispatched to the backend server with the following modifications.
	1. The "Sec-Token-Binding" header in the original incoming request		1. The "Sec-Token-Binding" header in the original incoming request
	MUST be removed from the request that is dispatched to the		MUST be removed from the request that is dispatched to the
	backend server.		backend server.
	skipping to change at page 6, line 45 ¶		skipping to change at page 6, line 45 ¶
	2.4. Examples		2.4. Examples
	Extra line breaks and whitespace have been added to the following		Extra line breaks and whitespace have been added to the following
	examples for display and formatting purposes only.		examples for display and formatting purposes only.
	2.4.1. Provided Token Binding ID		2.4.1. Provided Token Binding ID
	The following "Sec-Token-Binding" header is from an HTTP request made		The following "Sec-Token-Binding" header is from an HTTP request made
	over a TLS connection between the client and the TTRP where the use		over a TLS connection between the client and the TTRP where the use
	of Token Binding has been negotiated (The base64url-encoded		of Token Binding has been negotiated. The base64url-encoded
	representation of the exported keying material, which can be used to		representation of the exported keying material for that connection is
	validate the Token Binding Message, for that connection is		"AYVUayPTP9RmELNpGjFl6Ykm2CUx7pUMxe35yb11dgU", which can be used to
	"AYVUayPTP9RmELNpGjFl6Ykm2CUx7pUMxe35yb11dgU"). The encoded Token		validate the Token Binding Message. The encoded Token Binding
	Binding Message has the provided Token Binding that the client uses		Message has the provided Token Binding that the client uses with the
	with the server.		server.
	Sec-Token-Binding: AIkAAgBBQKzyIrmcY_YCtHVoSHBut69vrGfFdy1_YKTZfFJv		Sec-Token-Binding: AIkAAgBBQKzyIrmcY_YCtHVoSHBut69vrGfFdy1_YKTZfFJv
	6BjrZsKD9b9FRzSBxDs1twTqnAS71M1RBumuihhI9xqxXKkAQEtxe4jeUJU0WezxlQ		6BjrZsKD9b9FRzSBxDs1twTqnAS71M1RBumuihhI9xqxXKkAQEtxe4jeUJU0WezxlQ
	XWVSBFeHxFMdXRBIH_LKOSAuSMOJ0XEw1Q8DE248qkOiRKzw3KdSNYukYEPmO21bQi		XWVSBFeHxFMdXRBIH_LKOSAuSMOJ0XEw1Q8DE248qkOiRKzw3KdSNYukYEPmO21bQi
	3YYAAA		3YYAAA
	Figure 3: Header in HTTP Request to TTRP		Figure 3: Header in HTTP Request to TTRP
	After validating the Token Binding Message, the TTRP removes the		After validating the Token Binding Message, the TTRP removes the
	"Sec-Token-Binding" header and adds the following "Sec-Provided-		"Sec-Token-Binding" header and adds the following "Sec-Provided-
	skipping to change at page 7, line 26 ¶		skipping to change at page 7, line 26 ¶
	Sec-Provided-Token-Binding-ID: AgBBQKzyIrmcY_YCtHVoSHBut69vrGfFdy1_		Sec-Provided-Token-Binding-ID: AgBBQKzyIrmcY_YCtHVoSHBut69vrGfFdy1_
	YKTZfFJv6BjrZsKD9b9FRzSBxDs1twTqnAS71M1RBumuihhI9xqxXKk		YKTZfFJv6BjrZsKD9b9FRzSBxDs1twTqnAS71M1RBumuihhI9xqxXKk
	Figure 4: Header in HTTP Request to Backend Server		Figure 4: Header in HTTP Request to Backend Server
	2.4.2. Provided and Referred Token Binding IDs		2.4.2. Provided and Referred Token Binding IDs
	The following "Sec-Token-Binding" header is from an HTTP request made		The following "Sec-Token-Binding" header is from an HTTP request made
	over a TLS connection between the client and the TTRP where the use		over a TLS connection between the client and the TTRP where the use
	of Token Binding has been negotiated (The base64url-encoded		of Token Binding has been negotiated. The base64url-encoded
	representation of the exported keying material, which can be used to		representation of the exported keying material for that connection is
	validate the Token Binding Message, for that connection is		"wEWWCP1KPxfq-QL4NxYII_P4ti_9YYqrTpGs28BZEqE", which can be used to
	"wEWWCP1KPxfq-QL4NxYII_P4ti_9YYqrTpGs28BZEqE"). The encoded Token		validate the Token Binding Message. The encoded Token Binding
	Binding Message has the provided Token Binding that the client uses		Message has the provided Token Binding that the client uses with the
	with the server as well as the referred Token Binding that it uses		server as well as the referred Token Binding that it uses with a
	with a different server.		different server.
	Sec-Token-Binding: ARIAAgBBQCfsI1D1sTq5mvT_2H_dihNIvuHJCHGjHPJchPav		Sec-Token-Binding: ARIAAgBBQCfsI1D1sTq5mvT_2H_dihNIvuHJCHGjHPJchPav
	NbGrOo26-2JgT_IsbvZd4daDFbirYBIwJ-TK1rh8FzrC-psAQMyYIqXj7djGPev1dk		NbGrOo26-2JgT_IsbvZd4daDFbirYBIwJ-TK1rh8FzrC-psAQMyYIqXj7djGPev1dk
	jV9XxLYGCyqOrBVEtBHrMUCeo22ymLg3OiFcl_fmOPxJbjxI6lKcF0lyfy-dSQmPIe		jV9XxLYGCyqOrBVEtBHrMUCeo22ymLg3OiFcl_fmOPxJbjxI6lKcF0lyfy-dSQmPIe
	zQ0AAAECAEFArPIiuZxj9gK0dWhIcG63r2-sZ8V3LX9gpNl8Um_oGOtmwoP1v0VHNI		zQ0AAAECAEFArPIiuZxj9gK0dWhIcG63r2-sZ8V3LX9gpNl8Um_oGOtmwoP1v0VHNI
	HEOzW3BOqcBLvUzVEG6a6KGEj3GrFcqQBAHQm0pzgUTXKLRamuKE1pmmP9I3UBVpoe		HEOzW3BOqcBLvUzVEG6a6KGEj3GrFcqQBAHQm0pzgUTXKLRamuKE1pmmP9I3UBVpoe
	1DBCe9H2l1VPpsImakUa6crAqZ-0CGBmji7bYzQogpKcyxTTFk5zdwAA		1DBCe9H2l1VPpsImakUa6crAqZ-0CGBmji7bYzQogpKcyxTTFk5zdwAA
	Figure 5: Header in HTTP Request to TTRP		Figure 5: Header in HTTP Request to TTRP
	skipping to change at page 8, line 16 ¶		skipping to change at page 8, line 16 ¶
	HPJchPavNbGrOo26-2JgT_IsbvZd4daDFbirYBIwJ-TK1rh8FzrC-ps		HPJchPavNbGrOo26-2JgT_IsbvZd4daDFbirYBIwJ-TK1rh8FzrC-ps
	Sec-Referred-Token-Binding-ID: AgBBQKzyIrmcY_YCtHVoSHBut69vrGfFdy1_		Sec-Referred-Token-Binding-ID: AgBBQKzyIrmcY_YCtHVoSHBut69vrGfFdy1_
	YKTZfFJv6BjrZsKD9b9FRzSBxDs1twTqnAS71M1RBumuihhI9xqxXKk		YKTZfFJv6BjrZsKD9b9FRzSBxDs1twTqnAS71M1RBumuihhI9xqxXKk
	Figure 6: Headers in HTTP Request to Backend Server		Figure 6: Headers in HTTP Request to Backend Server
	2.4.3. Provided and Other Token Binding IDs		2.4.3. Provided and Other Token Binding IDs
	The following "Sec-Token-Binding" header is from an HTTP request made		The following "Sec-Token-Binding" header is from an HTTP request made
	over a TLS connection between the client and the TTRP where the use		over a TLS connection between the client and the TTRP where the use
	of Token Binding has been negotiated (The base64url-encoded		of Token Binding has been negotiated. The base64url-encoded
	representation of the exported keying material, which can be used to		representation of the exported keying material for that connection is
	validate the Token Binding Message, for that connection is		"Zr_1DESCcDoaltcZCK613UrEWHRf2B3w9i3bwcxpacc", which can be used to
	"Zr_1DESCcDoaltcZCK613UrEWHRf2B3w9i3bwcxpacc"). The encoded Token		validate the Token Binding Message. The encoded Token Binding
	Binding Message has the provided Token Binding and two other Token		Message has the provided Token Binding and two other Token Bindings.
	Bindings.
	Sec-Token-Binding: AZsAAgBBQA35hcCjI5GEHLLAZ0i2l2ZvQe-bSPAP7jovkZJM		Sec-Token-Binding: AZsAAgBBQA35hcCjI5GEHLLAZ0i2l2ZvQe-bSPAP7jovkZJM
	4wYHgmmXNd1aRpnQmXK9ghUmrdtS6p_e2uSlMXIVKOIwgysAQJ-TKyVGF37XUXMy79		4wYHgmmXNd1aRpnQmXK9ghUmrdtS6p_e2uSlMXIVKOIwgysAQJ-TKyVGF37XUXMy79
	ybwJyPpfCG9Iq6fdIxLX_yJn-L__Z3p_WIL3g17K0OH3XZmJS3qZNNEVu_8HmPN-d9		ybwJyPpfCG9Iq6fdIxLX_yJn-L__Z3p_WIL3g17K0OH3XZmJS3qZNNEVu_8HmPN-d9
	hGMAAE0CAEFAR68GbdIQyrHqkorJF0sekYJvf8iV03obGxbaWbqAEJetsYxprB6c3M		hGMAAE0CAEFAR68GbdIQyrHqkorJF0sekYJvf8iV03obGxbaWbqAEJetsYxprB6c3M
	x5KDHBGZjsFbeFW5Xec_EaxX0Hw3RmJwBA-Fu22kokRbB7G0D0g6_sdCHTbczSCmnm		x5KDHBGZjsFbeFW5Xec_EaxX0Hw3RmJwBA-Fu22kokRbB7G0D0g6_sdCHTbczSCmnm
	6rqP1x7kRIIj_kJNCCWcwMMFzbsBTXcm5fJrRdBTcsqiiqYD6aJ1SgAACwIAQUCDqt		6rqP1x7kRIIj_kJNCCWcwMMFzbsBTXcm5fJrRdBTcsqiiqYD6aJ1SgAACwIAQUCDqt
	6m63By8b1lvhN-n9OsQThoLomzKpMicSZGwR166jplhbkjrFsHzdNqzLFFEhCT9s0p		6m63By8b1lvhN-n9OsQThoLomzKpMicSZGwR166jplhbkjrFsHzdNqzLFFEhCT9s0p
	XrcbpOHsZnpRSkmhAEBfOwxjK3Y9EOeMrqjo0IUhmurW2EgtSRBjDwc0r-rDT231Zv		XrcbpOHsZnpRSkmhAEBfOwxjK3Y9EOeMrqjo0IUhmurW2EgtSRBjDwc0r-rDT231Zv
	_f1oePB8Pkd1kgAtgKX5EDiemfo1YER3_I2cv3AAA		_f1oePB8Pkd1kgAtgKX5EDiemfo1YER3_I2cv3AAA
	skipping to change at page 8, line 43 ¶		skipping to change at page 8, line 42 ¶
	Figure 7: Header in HTTP Request to TTRP		Figure 7: Header in HTTP Request to TTRP
	After validating the Token Binding Message, the TTRP removes the		After validating the Token Binding Message, the TTRP removes the
	"Sec-Token-Binding" header and adds the following "Sec-Provided-		"Sec-Token-Binding" header and adds the following "Sec-Provided-
	Token-Binding-ID" and "Sec-Other-Token-Binding-ID" headers to the		Token-Binding-ID" and "Sec-Other-Token-Binding-ID" headers to the
	request that is dispatched to the backend server.		request that is dispatched to the backend server.
	Sec-Provided-Token-Binding-ID: AgBBQA35hcCjI5GEHLLAZ0i2l2ZvQe-bSPAP		Sec-Provided-Token-Binding-ID: AgBBQA35hcCjI5GEHLLAZ0i2l2ZvQe-bSPAP
	7jovkZJM4wYHgmmXNd1aRpnQmXK9ghUmrdtS6p_e2uSlMXIVKOIwgys		7jovkZJM4wYHgmmXNd1aRpnQmXK9ghUmrdtS6p_e2uSlMXIVKOIwgys
	Sec-Other-Token-Binding-ID: 4d.AgBBQEevBm3SEMqx6pKKyRdLHpGCb3_IldN6		Sec-Other-Token-Binding-ID: 4d.AgBBQEevBm3SEMqx6pKKyRdLHpGCb3_IldN6
	GxsW2lm6gBCXrbGMaawenNzMeSgxwRmY7BW3hVuV3nPxGsV9B8N0Zic,b.AgBBQIO		GxsW2lm6gBCXrbGMaawenNzMeSgxwRmY7BW3hVuV3nPxGsV9B8N0Zic,B.AgBBQIO
	q3qbrcHLxvWW-E36f06xBOGguibMqkyJxJkbBHXrqOmWFuSOsWwfN02rMsUUSEJP2		q3qbrcHLxvWW-E36f06xBOGguibMqkyJxJkbBHXrqOmWFuSOsWwfN02rMsUUSEJP2
	zSletxuk4exmelFKSaE		zSletxuk4exmelFKSaE
	Figure 8: Headers in HTTP Request to Backend Server		Figure 8: Headers in HTTP Request to Backend Server
	3. Security Considerations		3. Security Considerations
			3.1. HTTP Headers
	The headers described herein enable a reverse proxy and backend		The headers described herein enable a reverse proxy and backend
	server to function together as though they are a single logical		server to function together as though they are a single logical
	server side deployment of HTTPS Token Binding. Use of the headers		server side deployment of HTTPS Token Binding. Use of the headers
	outside that intended use case, however, may undermine the		outside that intended use case, however, may undermine the
	protections afforded by Token Binding. Therefore steps MUST be taken		protections afforded by Token Binding. Therefore steps MUST be taken
	to prevent unintended use, both in sending the headers and in relying		to prevent unintended use, both in sending the headers and in relying
	on their value.		on their value.
	Producing and consuming the headers SHOULD be a configurable option,		Producing and consuming the headers SHOULD be a configurable option,
	skipping to change at page 9, line 48 ¶		skipping to change at page 9, line 47 ¶
	private network such that the backend application is only able to		private network such that the backend application is only able to
	accept requests from the reverse proxy and the proxy can only make		accept requests from the reverse proxy and the proxy can only make
	requests to that server. Other deployments that meet the		requests to that server. Other deployments that meet the
	requirements set forth herein are also possible.		requirements set forth herein are also possible.
	Employing the "Sec-" header field prefix for the headers defined		Employing the "Sec-" header field prefix for the headers defined
	herein denotes them as forbidden header names (see [fetch-spec]),		herein denotes them as forbidden header names (see [fetch-spec]),
	which means they cannot be set or modified programmatically by script		which means they cannot be set or modified programmatically by script
	running in-browser.		running in-browser.
			3.2. TLS Versions and Best Practices
			TLS 1.2 [RFC5246] is cited in this document because, at the time of
			writing, it is the latest version that is widely deployed. However,
			this document is applicable with other TLS versions that allow for
			negotiating the use of Token Binding. [I-D.ietf-tokbind-tls13], for
			example, describes Token Binding for TLS 1.3 [I-D.ietf-tls-tls13].
			Implementation security considerations for TLS, including version
			recommendations, can be found in Recommendations for Secure Use of
			Transport Layer Security (TLS) and Datagram Transport Layer Security
			(DTLS) [BCP195].
	4. IANA Considerations		4. IANA Considerations
	4.1. HTTP Message Header Field Names Registration		4.1. HTTP Message Header Field Names Registration
	This document specifies the following new HTTP header fields,		This document specifies the following new HTTP header fields,
	registration of which is requested in the "Permanent Message Header		registration of which is requested in the "Permanent Message Header
	Field Names" registry defined in [RFC3864].		Field Names" registry defined in [RFC3864].
	o Header Field Name: "Sec-Provided-Token-Binding-ID"		o Header Field Name: "Sec-Provided-Token-Binding-ID"
	o Applicable protocol: HTTP		o Applicable protocol: HTTP
	o Status: standard		o Status: standard
	o Author/change Controller: IETF		o Author/change Controller: IETF
	skipping to change at page 10, line 32 ¶		skipping to change at page 10, line 41 ¶
	o Header Field Name: "Sec-Other-Token-Binding-ID"		o Header Field Name: "Sec-Other-Token-Binding-ID"
	o Applicable protocol: HTTP		o Applicable protocol: HTTP
	o Status: standard		o Status: standard
	o Author/change Controller: IETF		o Author/change Controller: IETF
	o Specification Document(s): [[ this specification ]]		o Specification Document(s): [[ this specification ]]
	5. References		5. References
	5.1. Normative References		5.1. Normative References
			[BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre,
			"Recommendations for Secure Use of Transport Layer
			Security (TLS) and Datagram Transport Layer Security
			(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
			2015, <http://www.rfc-editor.org/info/bcp195>.
	[I-D.ietf-tokbind-https]		[I-D.ietf-tokbind-https]
	Popov, A., Nystrom, M., Balfanz, D., Langley, A., Harper,		Popov, A., Nystrom, M., Balfanz, D., Langley, A., Harper,
	N., and J. Hodges, "Token Binding over HTTP", draft-ietf-		N., and J. Hodges, "Token Binding over HTTP", draft-ietf-
	tokbind-https-12 (work in progress), January 2018.		tokbind-https-12 (work in progress), January 2018.
	[I-D.ietf-tokbind-negotiation]		[I-D.ietf-tokbind-negotiation]
	Popov, A., Nystrom, M., Balfanz, D., and A. Langley,		Popov, A., Nystrom, M., Balfanz, D., and A. Langley,
	"Transport Layer Security (TLS) Extension for Token		"Transport Layer Security (TLS) Extension for Token
	Binding Protocol Negotiation", draft-ietf-tokbind-		Binding Protocol Negotiation", draft-ietf-tokbind-
	negotiation-10 (work in progress), October 2017.		negotiation-10 (work in progress), October 2017.
	skipping to change at page 11, line 38 ¶		skipping to change at page 12, line 5 ¶
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	5.2. Informative References		5.2. Informative References
	[fetch-spec]		[fetch-spec]
	WhatWG, "Fetch", Living Standard ,		WhatWG, "Fetch", Living Standard ,
	<https://fetch.spec.whatwg.org/>.		<https://fetch.spec.whatwg.org/>.
			[I-D.ietf-tls-tls13]
			Rescorla, E., "The Transport Layer Security (TLS) Protocol
			Version 1.3", draft-ietf-tls-tls13-28 (work in progress),
			March 2018.
			[I-D.ietf-tokbind-tls13]
			Harper, N., "Token Binding for Transport Layer Security
			(TLS) Version 1.3 Connections", draft-ietf-tokbind-
			tls13-01 (work in progress), May 2018.
	[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration		[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
	Procedures for Message Header Fields", BCP 90, RFC 3864,		Procedures for Message Header Fields", BCP 90, RFC 3864,
	DOI 10.17487/RFC3864, September 2004,		DOI 10.17487/RFC3864, September 2004,
	<https://www.rfc-editor.org/info/rfc3864>.		<https://www.rfc-editor.org/info/rfc3864>.
	Appendix A. Acknowledgements		Appendix A. Acknowledgements
	The author would like to thank the following people for their various		The author would like to thank the following people for their various
	contributions to the specification: Vinod Anupam, Dirk Balfanz, John		contributions to the specification: Vinod Anupam, Dirk Balfanz, John
	Bradley, William Denniss, Nick Harper, Jeff Hodges, Subodh Iyengar,		Bradley, William Denniss, Nick Harper, Jeff Hodges, Subodh Iyengar,
	Leif Johansson, Michael B. Jones, Yoav Nir, James Manger, Andrei		Leif Johansson, Michael B. Jones, Yoav Nir, James Manger, Andrei
	Popov, Eric Rescorla, Piotr Sikora, Martin Thomson, and Hans Zandbelt		Popov, Eric Rescorla, Piotr Sikora, Martin Thomson, and Hans Zandbelt
	Appendix B. Document History		Appendix B. Document History
	[[ to be removed by the RFC Editor before publication as an RFC ]]		[[ to be removed by the RFC Editor before publication as an RFC ]]
			draft-ietf-tokbind-ttrp-05
			o Editorial updates.
			o Change one character in the last example to help emphasize the
			case-insensitivity of hex.
			o Add a TLS Versions and Best Practices section with BCP195 and also
			mention of ietf-tokbind-tls13 and ietf-tls-tls13.
	draft-ietf-tokbind-ttrp-04		draft-ietf-tokbind-ttrp-04
	o Add an example with Sec-Other-Token-Binding-ID.		o Add an example with Sec-Other-Token-Binding-ID.
	o Use the HEXDIG core ABNF rule for EncodedTokenBindingType and		o Use the HEXDIG core ABNF rule for EncodedTokenBindingType and
	mention case-insensitive in the text.		mention case-insensitive in the text.
	o Minor editorial fixes.		o Minor editorial fixes.
	o Add to the Acknowledgements and remove the 'and others' bit.		o Add to the Acknowledgements and remove the 'and others' bit.
	draft-ietf-tokbind-ttrp-03
	o Add a header to allow for additional token binding types other		o Add a header to allow for additional token binding types other
	than provided and referred to be conveyed.		than provided and referred to be conveyed.
	o Reword the Abstract somewhat for (hopefully) improved readability.		o Reword the Abstract somewhat for (hopefully) improved readability.
	o Minor editorial and formatting updates.		o Minor editorial and formatting updates.
	draft-ietf-tokbind-ttrp-02		draft-ietf-tokbind-ttrp-02
	o Add to the Acknowledgements.		o Add to the Acknowledgements.
	skipping to change at page 13, line 5 ¶		skipping to change at page 13, line 37 ¶
	o Prefix the header names with "Sec-" so that they are denoted as		o Prefix the header names with "Sec-" so that they are denoted as
	forbidden header names by Fetch https://fetch.spec.whatwg.org/		forbidden header names by Fetch https://fetch.spec.whatwg.org/
	o Removed potentially confusing sentence from Security		o Removed potentially confusing sentence from Security
	Considerations per		Considerations per
	https://mailarchive.ietf.org/arch/msg/unbearable/		https://mailarchive.ietf.org/arch/msg/unbearable/
	O0IpppyyEqMrQjEkyEi8p8CeBGA		O0IpppyyEqMrQjEkyEi8p8CeBGA
	o Editorial fixes.		o Editorial fixes.
			draft-ietf-tokbind-ttrp-00
	o Initial WG draft from draft-campbell-tokbind-ttrp.		o Initial WG draft from draft-campbell-tokbind-ttrp.
	draft-campbell-tokbind-ttrp-01		draft-campbell-tokbind-ttrp-01
	o Minor editorial fixes.		o Minor editorial fixes.
	o Add to the Acknowledgements.		o Add to the Acknowledgements.
	draft-campbell-tokbind-ttrp-00		draft-campbell-tokbind-ttrp-00
	o Initial draft based on 'consensus to work on the problem' from the		o Initial draft based on 'consensus to work on the problem' from the
	Seoul meeting [1][2] and reflecting the consensus approach from		Seoul meeting [1][2] and reflecting the consensus approach from
	discussions at the Chicago meeting [3].		discussions at the Chicago meeting [3].
	[1] https://www.ietf.org/proceedings/97/minutes/minutes-97-		[1] https://www.ietf.org/proceedings/97/minutes/minutes-97-
	tokbind-01.txt (minutes from Seoul)		tokbind-01.txt (minutes from Seoul)
	[2] https://www.ietf.org/proceedings/97/slides/slides-97-tokbind-		[2] https://www.ietf.org/proceedings/97/slides/slides-97-tokbind-
	reverse-proxies-00.pdf (slides from Seoul)		reverse-proxies-00.pdf (slides from Seoul)
	[3] https://mailarchive.ietf.org/arch/msg/		[3] https://mailarchive.ietf.org/arch/msg/
	unbearable/_ZHI8y2Vs5WMP8VMRr7zroo_sNU (summary of discussion)		unbearable/_ZHI8y2Vs5WMP8VMRr7zroo_sNU (summary of discussion)
End of changes. 26 change blocks.
	69 lines changed or deleted		108 lines changed or added
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