< draft-ietf-oauth-proof-of-possession-03.txt		draft-ietf-oauth-proof-of-possession-04.txt >
	OAuth Working Group M. Jones		OAuth Working Group M. Jones
	Internet-Draft Microsoft		Internet-Draft Microsoft
	Intended status: Standards Track J. Bradley		Intended status: Standards Track J. Bradley
	Expires: January 7, 2016 Ping Identity		Expires: February 29, 2016 Ping Identity
	H. Tschofenig		H. Tschofenig
	ARM Limited		ARM Limited
	July 6, 2015		August 28, 2015
	Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)		Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)
	draft-ietf-oauth-proof-of-possession-03		draft-ietf-oauth-proof-of-possession-04
	Abstract		Abstract
	This specification defines how to express a declaration in a JSON Web		This specification defines how to express a declaration in a JSON Web
	Token (JWT) that the presenter of the JWT possesses a particular key		Token (JWT) that the presenter of the JWT possesses a particular key
	and that the recipient can cryptographically confirm proof-of-		and that the recipient can cryptographically confirm proof-of-
	possession of the key by the presenter. This property is also		possession of the key by the presenter. This property is also
	sometimes described as the presenter being a holder-of-key.		sometimes described as the presenter being a holder-of-key.
	Status of this Memo		Status of this Memo
	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-
	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 January 7, 2016.		This Internet-Draft will expire on February 29, 2016.
	Copyright Notice		Copyright Notice
	Copyright (c) 2015 IETF Trust and the persons identified as the		Copyright (c) 2015 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 14 ¶		skipping to change at page 2, line 14 ¶
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 4		1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 4
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
	3. Representations for Proof-of-Possession Keys . . . . . . . . . 4		3. Representations for Proof-of-Possession Keys . . . . . . . . . 4
	3.1. Representation for an Asymmetric Proof-of-Possession		3.1. Confirmation Claim . . . . . . . . . . . . . . . . . . . . 5
	Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 5		3.2. Representation of an Asymmetric Proof-of-Possession Key . 5
	3.2. Representation for an Encrypted Symmetric		3.3. Representation of an Encrypted Symmetric
	Proof-of-Possession Key . . . . . . . . . . . . . . . . . 5		Proof-of-Possession Key . . . . . . . . . . . . . . . . . 6
	3.3. Representation of a Key ID for a Proof-of-Possession		3.4. Representation of a Key ID for a Proof-of-Possession
	Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 6		Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
	3.4. Confirmation . . . . . . . . . . . . . . . . . . . . . . . 7		3.5. Representation of a URL for a Proof-of-Possession Key . . 8
	3.5. Specifics Intentionally Not Specified . . . . . . . . . . 7		3.6. Specifics Intentionally Not Specified . . . . . . . . . . 8
	4. Security Considerations . . . . . . . . . . . . . . . . . . . 8		4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8		5. Privacy Considerations . . . . . . . . . . . . . . . . . . . . 9
	5.1. JSON Web Token Claims Registration . . . . . . . . . . . . 9		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
	5.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 10		6.1. JSON Web Token Claims Registration . . . . . . . . . . . . 11
	5.2. JWT Confirmation Methods Registry . . . . . . . . . . . . 10		6.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 11
	5.2.1. Registration Template . . . . . . . . . . . . . . . . 10		6.2. JWT Confirmation Methods Registry . . . . . . . . . . . . 11
	5.2.2. Initial Registry Contents . . . . . . . . . . . . . . 10		6.2.1. Registration Template . . . . . . . . . . . . . . . . 11
	6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11		6.2.2. Initial Registry Contents . . . . . . . . . . . . . . 12
	6.1. Normative References . . . . . . . . . . . . . . . . . . . 11		7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
	6.2. Informative References . . . . . . . . . . . . . . . . . . 11		7.1. Normative References . . . . . . . . . . . . . . . . . . . 12
	Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 12		7.2. Informative References . . . . . . . . . . . . . . . . . . 13
	Appendix B. Document History . . . . . . . . . . . . . . . . . . 12		Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 14
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13		Appendix B. Document History . . . . . . . . . . . . . . . . . . 14
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
	1. Introduction		1. Introduction
	This specification defines how to express a declaration in a JSON Web		This specification defines how to express a declaration in a JSON Web
	Token (JWT) [JWT] that the presenter of the JWT possesses a		Token (JWT) [JWT] that the presenter of the JWT possesses a
	particular key and that the recipient can cryptographically confirm		particular key and that the recipient can cryptographically confirm
	proof-of-possession of the key by the presenter. This property is		proof-of-possession of the key by the presenter. This property is
	also sometimes described as the presenter being a holder-of-key.		also sometimes described as the presenter being a holder-of-key. See
			[I-D.ietf-oauth-pop-architecture] for a further discussion of key
			confirmation.
	Envision the following two use cases. The first use case describes		Envision the following two use cases. The first use case describes
	the use of a symmetric proof-of-possession key and the second use		the use of a symmetric proof-of-possession key and the second use
	case uses an asymmetric proof-of-possession key.		case uses an asymmetric proof-of-possession key.
	An issuer generates a JWT and places an encrypted symmetric key		An issuer generates a JWT and places an encrypted symmetric key
	inside the newly introduced confirmation claim. This symmetric key		inside the newly introduced confirmation claim. This symmetric key
	is encrypted with a key known only to the issuer and the recipient.		is encrypted with a key known only to the issuer and the recipient.
	The entire JWT is then integrity protected by the issuer. The JWT is		The entire JWT is then integrity protected by the issuer. The JWT is
	then sent to the presenter. Since the presenter is unable to obtain		then sent to the presenter. Since the presenter is unable to obtain
	skipping to change at page 3, line 52 ¶		skipping to change at page 4, line 5 ¶
	modifications. The JWT is then sent to the presenter. When the		modifications. The JWT is then sent to the presenter. When the
	presenter needs to present the JWT to the recipient, it also needs to		presenter needs to present the JWT to the recipient, it also needs to
	demonstrate possession of the private key. The presenter, for		demonstrate possession of the private key. The presenter, for
	example, uses the private key in a TLS exchange with the recipient or		example, uses the private key in a TLS exchange with the recipient or
	signs a nonce with the private key. The recipient is able to verify		signs a nonce with the private key. The recipient is able to verify
	that it is interacting with the genuine presenter by extracting the		that it is interacting with the genuine presenter by extracting the
	public key from the confirmation claim of the JWT (after verifying		public key from the confirmation claim of the JWT (after verifying
	the digital signature of the JWT) and utilizing it with the private		the digital signature of the JWT) and utilizing it with the private
	key in the TLS exchange or checking the nonce signature.		key in the TLS exchange or checking the nonce signature.
	In both cases the JWT may contain other claims that are needed by the		In both cases, the JWT may contain other claims that are needed by
	application.		the application.
	1.1. Notational Conventions		1.1. 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", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in RFC		"OPTIONAL" in this document are to be interpreted as described in RFC
	2119 [RFC2119].		2119 [RFC2119].
	Unless otherwise noted, all the protocol parameter names and values		Unless otherwise noted, all the protocol parameter names and values
	are case sensitive.		are case sensitive.
	skipping to change at page 4, line 31 ¶		skipping to change at page 4, line 33 ¶
	These terms are defined by this specification:		These terms are defined by this specification:
	Issuer		Issuer
	Party that creates the JWT and binds the proof-of-possession key		Party that creates the JWT and binds the proof-of-possession key
	to it.		to it.
	Presenter		Presenter
	Party that proves possession of a private key (for asymmetric key		Party that proves possession of a private key (for asymmetric key
	cryptography) or secret key (for symmetric key cryptography) to a		cryptography) or secret key (for symmetric key cryptography) to a
	recipient. The presenter may be the issuer or a party distinct		recipient.
	from the issuer.
	Recipient		Recipient
	Party that receives the JWT containing the proof-of-possession key		Party that receives the JWT containing the proof-of-possession key
	information from the presenter.		information from the presenter.
	3. Representations for Proof-of-Possession Keys		3. Representations for Proof-of-Possession Keys
	The issuer of a JWT declares that the presenter possesses a		The issuer of a JWT declares that the presenter possesses a
	particular key and that the recipient can cryptographically confirm		particular key and that the recipient can cryptographically confirm
	proof-of-possession of the key by the presenter by including a "cnf"		proof-of-possession of the key by the presenter by including a "cnf"
	(confirmation) claim in the JWT whose value is a JSON object, with a		(confirmation) claim in the JWT whose value is a JSON object.
	JSON object containing a "jwk" (JSON Web Key) member, a "jwe" (JSON		Members in the JSON object identify the proof-of-possession key.
	Web Encryption) member, or a "kid" (key ID) member identifying the
	key.
	The presenter can be identified in one of several ways by the JWT,		The presenter can be identified in one of several ways by the JWT,
	depending upon the application requirements. If the JWT contains a		depending upon the application requirements. If the JWT contains a
	"sub" (subject) claim, the presenter is normally the subject		"sub" (subject) claim, the presenter is normally the subject
	identified by the JWT. (In some applications, the subject identifier		identified by the JWT. (In some applications, the subject identifier
	will be relative to the issuer identified by the "iss" (issuer)		will be relative to the issuer identified by the "iss" (issuer)
	claim.) If the JWT contains no "sub" (subject) claim, the presenter		claim.) If the JWT contains no "sub" (subject) claim, the presenter
	is normally the issuer identified by the JWT using the "iss" (issuer)		is normally the issuer identified by the JWT using the "iss" (issuer)
	claim. The case in which the presenter is the subject of the JWT is		claim. The case in which the presenter is the subject of the JWT is
	analogous to SAML 2.0 [OASIS.saml-core-2.0-os] SubjectConfirmation		analogous to SAML 2.0 [OASIS.saml-core-2.0-os] SubjectConfirmation
	usage. At least one of the "sub" and "iss" claims MUST be present in		usage. At least one of the "sub" and "iss" claims MUST be present in
	the JWT. Some use cases may require that both be present.		the JWT. Some use cases may require that both be present.
	Another means used by some applications to identify the presenter is		Another means used by some applications to identify the presenter is
	an explicit claim, such as the "azp" (authorized party) claim defined		an explicit claim, such as the "azp" (authorized party) claim defined
	by OpenID Connect [OpenID.Core]. Ultimately, the means of		by OpenID Connect [OpenID.Core]. Ultimately, the means of
	identifying the presenter is application-specific, as is the means of		identifying the presenter is application-specific, as is the means of
	confirming possession of the key that is communicated.		confirming possession of the key that is communicated.
	3.1. Representation for an Asymmetric Proof-of-Possession Key		3.1. Confirmation Claim
			The "cnf" (confirmation) claim is used in the JWT to contain members
			used to identify the proof-of-possession key. Other members of the
			"cnf" object may be defined because a proof-of-possession key may not
			be the only means of confirming the authenticity of the token. This
			is analogous to the SAML 2.0 [OASIS.saml-core-2.0-os]
			SubjectConfirmation element, in which a number of different subject
			confirmation methods can be included, including proof-of-possession
			key information. When a recipient receives a "cnf" claim with a
			member that it does not understand, it MUST ignore that member.
			This specification establishes the IANA "JWT Confirmation Methods"
			registry for these members in Section 6.2 and registers the members
			defined by this specification. Other specifications can register
			other members used for confirmation, including other members for
			conveying proof-of-possession keys, possibly using different key
			representations.
			Note that if an application needs to represent multiple proof-of-
			possession keys in the same JWT, one way for it to achieve this is to
			use other claim names, in addition to "cnf", to hold the additional
			proof-of-possession key information. These claims could use the same
			syntax and semantics as the "cnf" claim.
			3.2. Representation of an Asymmetric Proof-of-Possession Key
	When the key held by the presenter is an asymmetric private key, the		When the key held by the presenter is an asymmetric private key, the
	"jwk" member is a JSON Web Key (JWK) [JWK] representing the		"jwk" member is a JSON Web Key (JWK) [JWK] representing the
	corresponding asymmetric public key. The following example		corresponding asymmetric public key. The following example
	demonstrates such a declaration in the JWT Claims Set of a JWT:		demonstrates such a declaration in the JWT Claims Set of a JWT:
	{		{
	"iss": "https://server.example.com",		"iss": "https://server.example.com",
	"aud": "https://client.example.org",		"aud": "https://client.example.org",
	"exp": "1361398824",		"exp": "1361398824",
	"nbf": "1360189224",
	"cnf":{		"cnf":{
	"jwk":{		"jwk":{
	"kty": "EC",		"kty": "EC",
	"use": "sig",		"use": "sig",
	"crv": "P-256",		"crv": "P-256",
	"x": "18wHLeIgW9wVN6VD1Txgpqy2LszYkMf6J8njVAibvhM",		"x": "18wHLeIgW9wVN6VD1Txgpqy2LszYkMf6J8njVAibvhM",
	"y": "-V4dS4UaLMgP_4fY4j8ir7cl1TXlFdAgcx55o7TkcSA"		"y": "-V4dS4UaLMgP_4fY4j8ir7cl1TXlFdAgcx55o7TkcSA"
	}		}
	}		}
	}		}
	The JWK MUST contain the required key members for a JWK of that key		The JWK MUST contain the required key members for a JWK of that key
	type and MAY contain other JWK members, including the "kid" (key ID)		type and MAY contain other JWK members, including the "kid" (key ID)
	member.		member.
	3.2. Representation for an Encrypted Symmetric Proof-of-Possession Key		The "jwk" member MAY also be used for a JWK representing a symmetric
			key, provided that the JWT is encrypted so that the key is not
			revealed to unintended parties. If the JWT is not encrypted, the
			symmetric key MUST be encrypted as described below.
			3.3. Representation of an Encrypted Symmetric Proof-of-Possession Key
	When the key held by the presenter is a symmetric key, the "jwe"		When the key held by the presenter is a symmetric key, the "jwe"
	member is an encrypted JSON Web Key (JWK) [JWK] encrypted to a key		member is an encrypted JSON Web Key (JWK) [JWK] encrypted to a key
	known to the recipient using the JWE Compact Serialization containing		known to the recipient using the JWE Compact Serialization containing
	the symmetric key. The rules for encrypting a JWK are found in		the symmetric key. The rules for encrypting a JWK are found in
	Section 7 of the JSON Web Key [JWK] specification.		Section 7 of the JSON Web Key [JWK] specification.
	The following example illustrates a symmetric key that could		The following example illustrates a symmetric key that could
	subsequently be encrypted for use in the "jwe" member:		subsequently be encrypted for use in the "jwe" member:
	{		{
	"kty": "oct",		"kty": "oct",
	"alg": "HS256",		"alg": "HS256",
	"k": "ZoRSOrFzN_FzUA5XKMYoVHyzff5oRJxl-IXRtztJ6uE"		"k": "ZoRSOrFzN_FzUA5XKMYoVHyzff5oRJxl-IXRtztJ6uE"
	}		}
	The UTF-8 [RFC3629] encoding of this JWK would be used as the JWE		The UTF-8 [RFC3629] encoding of this JWK is used as the JWE Plaintext
	Plaintext when encrypting the key.		when encrypting the key.
	The following example is a JWE Header that could be used when		The following example is a JWE Header that could be used when
	encrypting this key:		encrypting this key:
	{		{
	"alg": "RSA1_5",		"alg": "RSA-OAEP",
	"enc": "A128CBC-HS256"		"enc": "A128CBC-HS256"
	}		}
	The following example JWT Claims Set of a JWT illustrates the use of		The following example JWT Claims Set of a JWT illustrates the use of
	an encrypted symmetric key as the "jwe" member value:		an encrypted symmetric key as the "jwe" member value:
	{		{
	"iss": "https://server.example.com",		"iss": "https://server.example.com",
	"sub": "24400320",		"sub": "24400320",
	"aud": "s6BhdRkqt3",		"aud": "s6BhdRkqt3",
	"nonce": "n-0S6_WzA2Mj",		"nonce": "n-0S6_WzA2Mj",
	"exp": 1311281970,		"exp": 1311281970,
	"iat": 1311280970,		"iat": 1311280970,
	"cnf":{		"cnf":{
	"jwe":		"jwe":
	"eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.		"eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkExMjhDQkMtSFMyNTYifQ.
	(remainder of JWE omitted for brevity)"		(remainder of JWE omitted for brevity)"
	}		}
	}		}
	3.3. Representation of a Key ID for a Proof-of-Possession Key		3.4. Representation of a Key ID for a Proof-of-Possession Key
	The proof-of-possession key can also be identified by the use of a		The proof-of-possession key can also be identified by the use of a
	Key ID instead of communicating the actual key, provided the		Key ID instead of communicating the actual key, provided the
	recipient is able to obtain the identified key using the Key ID. In		recipient is able to obtain the identified key using the Key ID. In
	this case, the issuer of a JWT declares that the presenter possesses		this case, the issuer of a JWT declares that the presenter possesses
	a particular key and that the recipient can cryptographically confirm		a particular key and that the recipient can cryptographically confirm
	proof-of-possession of the key by the presenter by including a "cnf"		proof-of-possession of the key by the presenter by including a "cnf"
	(confirmation) claim in the JWT whose value is a JSON object, with		(confirmation) claim in the JWT whose value is a JSON object, with
	the JSON object containing a "kid" (key ID) member identifying the		the JSON object containing a "kid" (key ID) member identifying the
	key.		key.
	The following example demonstrates such a declaration in the JWT		The following example demonstrates such a declaration in the JWT
	Claims Set of a JWT:		Claims Set of a JWT:
	{		{
	"iss": "https://server.example.com",		"iss": "https://server.example.com",
	"aud": "https://client.example.org",		"aud": "https://client.example.org",
	"exp": "1361398824",		"exp": "1361398824",
	"nbf": "1360189224",
	"cnf":{		"cnf":{
	"kid": "dfd1aa97-6d8d-4575-a0fe-34b96de2bfad"		"kid": "dfd1aa97-6d8d-4575-a0fe-34b96de2bfad"
	}		}
	}		}
	3.4. Confirmation		The content of the "kid" value is application specific. For
			instance, some applications may choose to use a JWK Thumbprint
	The "cnf" (confirmation) claim is used in the JWT to contain the		[JWK.Thumbprint] value as the "kid" value.
	"jwk", "jwe", or "kid" member because a proof-of-possession key may
	not be the only means of confirming the authenticity of the token.
	This is analogous to the SAML 2.0 [OASIS.saml-core-2.0-os]
	SubjectConfirmation element, in which a number of different subject
	confirmation methods can be included, including proof-of-possession
	key information. When a recipient receives a "cnf" claim with a
	member that it does not understand, it MUST ignore that member.
	This specification establishes the IANA "JWT Confirmation Methods"		3.5. Representation of a URL for a Proof-of-Possession Key
	registry for these members in Section 5.2 and registers the "jwk",
	"jwe", and "kid" members within the registry. Other specifications
	can register other members used for confirmation, including members
	for conveying other proof-of-possession keys, possibly using
	different key representations.
	3.5. Specifics Intentionally Not Specified		The proof-of-possession key can be passed by reference instead of
			being passed by value. This is done using the "jku" (JWK Set URL)
			member. Its value is a URI [RFC3986] that refers to a resource for a
			set of JSON-encoded public keys represented as a JWK Set [JWK], one
			of which is the proof-of-possession key. If there are multiple keys
			in the referenced JWK Set document, a "kid" member MUST also be
			included, with the referenced key's JWK also containing the same
			"kid" value.
			The protocol used to acquire the resource MUST provide integrity
			protection; an HTTP GET request to retrieve the JWK Set MUST use
			Transport Layer Security (TLS) [RFC5246]; and the identity of the
			server MUST be validated, as per Section 6 of RFC 6125 [RFC6125].
			The following example demonstrates such a declaration in the JWT
			Claims Set of a JWT:
			{
			"iss": "https://server.example.com",
			"sub": "17760704",
			"aud": "https://client.example.org",
			"exp": "1440804813",
			"cnf":{
			"jku": "https://keys.example.net/pop-keys.json",
			"kid": "2015-08-28"
			}
			}
			3.6. Specifics Intentionally Not Specified
	Proof-of-possession is typically demonstrated by having the presenter		Proof-of-possession is typically demonstrated by having the presenter
	sign a value determined by the recipient using the key possessed by		sign a value determined by the recipient using the key possessed by
	the presenter. This value is sometimes called a "nonce" or a		the presenter. This value is sometimes called a "nonce" or a
	"challenge".		"challenge".
	The means of communicating the nonce and the nature of its contents		The means of communicating the nonce and the nature of its contents
	are intentionally not described in this specification, as different		are intentionally not described in this specification, as different
	protocols will communicate this information in different ways.		protocols will communicate this information in different ways.
	Likewise, the means of communicating the signed nonce is also not		Likewise, the means of communicating the signed nonce is also not
	specified, as this is also protocol-specific.		specified, as this is also protocol-specific.
	Note that another means of proving possession of the key when it is a		Note that another means of proving possession of the key when it is a
	symmetric key is to encrypt the key to the recipient. The means of		symmetric key is to encrypt the key to the recipient. The means of
	obtaining a key for the recipient is likewise protocol-specific.		obtaining a key for the recipient is likewise protocol-specific.
	For an example specification that uses the mechanisms defined in this		For examples using the mechanisms defined in this specification, see
	document, see [I-D.ietf-oauth-pop-architecture].		[I-D.ietf-oauth-pop-architecture].
	4. Security Considerations		4. Security Considerations
	All of the normal security issues, especially in relationship to		All of the normal security issues, especially in relationship to
	comparing URIs and dealing with unrecognized values, that are		comparing URIs and dealing with unrecognized values, that are
	discussed in JWT [JWT] also apply here.		discussed in JWT [JWT] also apply here.
	In addition, proof-of-possession introduces its own unique security		In addition, proof-of-possession introduces its own unique security
	issues. Possessing the key is only valuable if it is kept secret.		issues. Possessing the key is only valuable if it is kept secret.
	Appropriate means must be used to ensure that unintended parties do		Appropriate means must be used to ensure that unintended parties do
	skipping to change at page 8, line 46 ¶		skipping to change at page 9, line 42 ¶
	those not only require integrity protection, but also confidentiality		those not only require integrity protection, but also confidentiality
	protection.		protection.
	A recipient may not understand the newly introduced "cnf" claim and		A recipient may not understand the newly introduced "cnf" claim and
	may consequently treat it as a bearer token. While this is a		may consequently treat it as a bearer token. While this is a
	legitimate concern, it is outside the scope of this specification,		legitimate concern, it is outside the scope of this specification,
	since demonstration the possession of the key associated with the		since demonstration the possession of the key associated with the
	"cnf" claim is not covered by this specification. For more details,		"cnf" claim is not covered by this specification. For more details,
	please consult [I-D.ietf-oauth-pop-architecture].		please consult [I-D.ietf-oauth-pop-architecture].
	5. IANA Considerations		5. Privacy Considerations
			A proof-of-possession key can be used as a correlation handle if the
			same key is used with multiple parties. Thus, for privacy reasons,
			it is recommended that different proof-of-possession keys be used
			when interacting with different parties.
			6. IANA Considerations
	The following registration procedure is used for all the registries		The following registration procedure is used for all the registries
	established by this specification.		established by this specification.
	Values are registered on a Specification Required [RFC5226] basis		Values are registered on a Specification Required [RFC5226] basis
	after a three-week review period on the oauth-pop-reg-review@ietf.org		after a three-week review period on the oauth-pop-reg-review@ietf.org
	mailing list, on the advice of one or more Designated Experts.		mailing list, on the advice of one or more Designated Experts.
	However, to allow for the allocation of values prior to publication,		However, to allow for the allocation of values prior to publication,
	the Designated Experts may approve registration once they are		the Designated Experts may approve registration once they are
	satisfied that such a specification will be published. [[ Note to the		satisfied that such a specification will be published. [[ Note to the
	skipping to change at page 9, line 45 ¶		skipping to change at page 11, line 5 ¶
	list.		list.
	It is suggested that multiple Designated Experts be appointed who are		It is suggested that multiple Designated Experts be appointed who are
	able to represent the perspectives of different applications using		able to represent the perspectives of different applications using
	this specification, in order to enable broadly-informed review of		this specification, in order to enable broadly-informed review of
	registration decisions. In cases where a registration decision could		registration decisions. In cases where a registration decision could
	be perceived as creating a conflict of interest for a particular		be perceived as creating a conflict of interest for a particular
	Expert, that Expert should defer to the judgment of the other		Expert, that Expert should defer to the judgment of the other
	Experts.		Experts.
	5.1. JSON Web Token Claims Registration		6.1. JSON Web Token Claims Registration
	This specification registers the "cnf" claim in the IANA JSON Web		This specification registers the "cnf" claim in the IANA "JSON Web
	Token Claims registry defined in [JWT].		Token Claims" registry [IANA.JWT.Claims] established by [JWT].
	5.1.1. Registry Contents		6.1.1. Registry Contents
	o Claim Name: "cnf"		o Claim Name: "cnf"
	o Claim Description: Confirmation		o Claim Description: Confirmation
	o Change Controller: IESG		o Change Controller: IESG
	o Specification Document(s): Section 3.4 of this document		o Specification Document(s): Section 3.1 of [[ this document ]]
	5.2. JWT Confirmation Methods Registry		6.2. JWT Confirmation Methods Registry
	This specification establishes the IANA "JWT Confirmation Methods"		This specification establishes the IANA "JWT Confirmation Methods"
	registry for JWT "cnf" member values. The registry records the		registry for JWT "cnf" member values. The registry records the
	confirmation method member and a reference to the specification that		confirmation method member and a reference to the specification that
	defines it.		defines it.
	5.2.1. Registration Template		6.2.1. Registration Template
	Confirmation Method Value:		Confirmation Method Value:
	The name requested (e.g., "kid"). Because a core goal of this		The name requested (e.g., "kid"). Because a core goal of this
	specification is for the resulting representations to be compact,		specification is for the resulting representations to be compact,
	it is RECOMMENDED that the name be short -- not to exceed 8		it is RECOMMENDED that the name be short -- not to exceed 8
	characters without a compelling reason to do so. This name is		characters without a compelling reason to do so. This name is
	case-sensitive. Names may not match other registered names in a		case-sensitive. Names may not match other registered names in a
	case-insensitive manner unless the Designated Experts state that		case-insensitive manner unless the Designated Experts state that
	there is a compelling reason to allow an exception.		there is a compelling reason to allow an exception.
	skipping to change at page 10, line 45 ¶		skipping to change at page 12, line 5 ¶
	For Standards Track RFCs, list the "IESG". For others, give the		For Standards Track RFCs, list the "IESG". For others, give the
	name of the responsible party. Other details (e.g., postal		name of the responsible party. Other details (e.g., postal
	address, email address, home page URI) may also be included.		address, email address, home page URI) may also be included.
	Specification Document(s):		Specification Document(s):
	Reference to the document or documents that specify the parameter,		Reference to the document or documents that specify the parameter,
	preferably including URIs that can be used to retrieve copies of		preferably including URIs that can be used to retrieve copies of
	the documents. An indication of the relevant sections may also be		the documents. An indication of the relevant sections may also be
	included but is not required.		included but is not required.
	5.2.2. Initial Registry Contents		6.2.2. Initial Registry Contents
	o Confirmation Method Value: "jwk"		o Confirmation Method Value: "jwk"
	o Confirmation Method Description: JSON Web Key Representing Public		o Confirmation Method Description: JSON Web Key Representing Public
	Key		Key
	o Change Controller: IESG		o Change Controller: IESG
	o Specification Document(s): Section 3.1 of [[ this document ]]		o Specification Document(s): Section 3.2 of [[ this document ]]
	o Confirmation Method Value: "jwe"		o Confirmation Method Value: "jwe"
	o Confirmation Method Description: Encrypted JSON Web Key		o Confirmation Method Description: Encrypted JSON Web Key
	o Change Controller: IESG		o Change Controller: IESG
	o Specification Document(s): Section 3.2 of [[ this document ]]		o Specification Document(s): Section 3.3 of [[ this document ]]
	o Confirmation Method Value: "kid"		o Confirmation Method Value: "kid"
	o Confirmation Method Description: Key Identifier		o Confirmation Method Description: Key Identifier
	o Change Controller: IESG		o Change Controller: IESG
	o Specification Document(s): Section 3.3 of [[ this document ]]		o Specification Document(s): Section 3.4 of [[ this document ]]
	6. References		o Confirmation Method Value: "jku"
			o Confirmation Method Description: JWK Set URL
			o Change Controller: IESG
			o Specification Document(s): Section 3.5 of [[ this document ]]
	6.1. Normative References		7. References
			7.1. Normative References
			[IANA.JWT.Claims]
			IANA, "JSON Web Token Claims",
			<http://www.iana.org/assignments/jwt>.
	[JWE] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",		[JWE] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
	RFC 7516, May 2015,		RFC 7516, May 2015,
	<http://www.rfc-editor.org/info/rfc7516>.		<http://www.rfc-editor.org/info/rfc7516>.
	[JWK] Jones, M., "JSON Web Key (JWK)", RFC 7517, May 2015,		[JWK] Jones, M., "JSON Web Key (JWK)", RFC 7517, May 2015,
	<http://www.rfc-editor.org/info/rfc7517>.		<http://www.rfc-editor.org/info/rfc7517>.
	[JWT] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token		[JWT] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
	(JWT)", RFC 7519, May 2015,		(JWT)", RFC 7519, May 2015,
	<http://www.rfc-editor.org/info/rfc7519>.		<http://www.rfc-editor.org/info/rfc7519>.
	[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>.
	[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO		[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
	10646", STD 63, RFC 3629, November 2003.		10646", STD 63, RFC 3629, DOI 10.17487/RFC3629,
			November 2003, <http://www.rfc-editor.org/info/rfc3629>.
			[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
			Resource Identifier (URI): Generic Syntax", STD 66,
			RFC 3986, DOI 10.17487/RFC3986, January 2005,
			<http://www.rfc-editor.org/info/rfc3986>.
	[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.		DOI 10.17487/RFC5226, May 2008,
			<http://www.rfc-editor.org/info/rfc5226>.
	6.2. Informative References		[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
			(TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/
			RFC5246, August 2008,
			<http://www.rfc-editor.org/info/rfc5246>.
			[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
			Verification of Domain-Based Application Service Identity
			within Internet Public Key Infrastructure Using X.509
			(PKIX) Certificates in the Context of Transport Layer
			Security (TLS)", RFC 6125, DOI 10.17487/RFC6125,
			March 2011, <http://www.rfc-editor.org/info/rfc6125>.
			7.2. Informative References
	[I-D.ietf-oauth-pop-architecture]		[I-D.ietf-oauth-pop-architecture]
	Hunt, P., Richer, J., Mills, W., Mishra, P., and H.		Hunt, P., Richer, J., Mills, W., Mishra, P., and H.
	Tschofenig, "OAuth 2.0 Proof-of-Possession (PoP) Security		Tschofenig, "OAuth 2.0 Proof-of-Possession (PoP) Security
	Architecture", draft-ietf-oauth-pop-architecture-01 (work		Architecture", draft-ietf-oauth-pop-architecture-01 (work
	in progress), March 2015.		in progress), March 2015.
			[JWK.Thumbprint]
			Jones, M. and N. Sakimura, "JSON Web Key (JWK)
			Thumbprint", draft-ietf-jose-jwk-thumbprint (work in
			progress), July 2015, <http://tools.ietf.org/html/
			draft-ietf-jose-jwk-thumbprint-08>.
	[OASIS.saml-core-2.0-os]		[OASIS.saml-core-2.0-os]
	Cantor, S., Kemp, J., Philpott, R., and E. Maler,		Cantor, S., Kemp, J., Philpott, R., and E. Maler,
	"Assertions and Protocol for the OASIS Security Assertion		"Assertions and Protocol for the OASIS Security Assertion
	Markup Language (SAML) V2.0", OASIS Standard saml-core-		Markup Language (SAML) V2.0", OASIS Standard saml-core-
	2.0-os, March 2005.		2.0-os, March 2005.
	[OpenID.Core]		[OpenID.Core]
	Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and		Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
	C. Mortimore, "OpenID Connect Core 1.0", November 2014,		C. Mortimore, "OpenID Connect Core 1.0", November 2014,
	<http://openid.net/specs/openid-connect-core-1_0.html>.		<http://openid.net/specs/openid-connect-core-1_0.html>.
	Appendix A. Acknowledgements		Appendix A. Acknowledgements
	The authors wish to thank Brian Campbell, James Manger, Justin		The authors wish to thank Brian Campbell, James Manger, Justin
	Richer, and Nat Sakimura for their reviews of the specification.		Richer, and Nat Sakimura for their reviews of the specification.
	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 ]]
			-04
			o Allowed the use of "jwk" for symmetric keys when the JWT is
			encrypted.
			o Added the "jku" (JWK Set URL) member.
			o Added privacy considerations.
			o Reordered sections so that the "cnf" (confirmation) claim is
			defined before it is used.
			o Noted that applications can define new claim names, in addition to
			"cnf", to represent additional proof-of-possession keys, using the
			same representation as "cnf".
			o Applied wording clarifications suggested by Nat Sakimura.
	-03		-03
	o Separated the "jwk" and "jwe" confirmation members; the former		o Separated the "jwk" and "jwe" confirmation members; the former
	represents a public key as a JWK and the latter represents a		represents a public key as a JWK and the latter represents a
	symmetric key as a JWE encrypted JWK.		symmetric key as a JWE encrypted JWK.
	o Changed the title to indicate that a proof-of-possession key is		o Changed the title to indicate that a proof-of-possession key is
	being communicated.		being communicated.
	o Updated language that formerly assumed that the issuer was an		o Updated language that formerly assumed that the issuer was an
End of changes. 41 change blocks.
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