< draft-ietf-oauth-jwt-bcp-01.txt		draft-ietf-oauth-jwt-bcp-02.txt >
	OAuth Working Group Y. Sheffer		OAuth Working Group Y. Sheffer
	Internet-Draft Intuit		Internet-Draft Intuit
	Intended status: Best Current Practice D. Hardt		Intended status: Best Current Practice D. Hardt
	Expires: September 24, 2018 Amazon		Expires: November 3, 2018 Amazon
	M. Jones		M. Jones
	Microsoft		Microsoft
	March 23, 2018		May 02, 2018
	JSON Web Token Best Current Practices		JSON Web Token Best Current Practices
	draft-ietf-oauth-jwt-bcp-01		draft-ietf-oauth-jwt-bcp-02
	Abstract		Abstract
	JSON Web Tokens, also known as JWTs [RFC7519], are URL-safe JSON-		JSON Web Tokens, also known as JWTs, are URL-safe JSON-based security
	based security tokens that contain a set of claims that can be signed		tokens that contain a set of claims that can be signed and/or
	and/or encrypted. JWTs are being widely used and deployed as a		encrypted. JWTs are being widely used and deployed as a simple
	simple security token format in numerous protocols and applications,		security token format in numerous protocols and applications, both in
	both in the area of digital identity, and in other application areas.		the area of digital identity, and in other application areas. The
	The goal of this Best Current Practices document is to provide		goal of this Best Current Practices document is to provide actionable
	actionable guidance leading to secure implementation and deployment		guidance leading to secure implementation and deployment of JWTs.
	of JWTs.
	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
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 September 24, 2018.		This Internet-Draft will expire on November 3, 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.
	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 27 ¶		skipping to change at page 2, line 26 ¶
	2.1. Weak Signatures and Insufficient Signature Validation . . 4		2.1. Weak Signatures and Insufficient Signature Validation . . 4
	2.2. Weak symmetric keys . . . . . . . . . . . . . . . . . . . 4		2.2. Weak symmetric keys . . . . . . . . . . . . . . . . . . . 4
	2.3. Multiplicity of JSON encodings . . . . . . . . . . . . . 5		2.3. Multiplicity of JSON encodings . . . . . . . . . . . . . 5
	2.4. Incorrect Composition of Encryption and Signature . . . . 5		2.4. Incorrect Composition of Encryption and Signature . . . . 5
	2.5. Insecure Use of Elliptic Curve Encryption . . . . . . . . 5		2.5. Insecure Use of Elliptic Curve Encryption . . . . . . . . 5
	2.6. Substitution Attacks . . . . . . . . . . . . . . . . . . 5		2.6. Substitution Attacks . . . . . . . . . . . . . . . . . . 5
	2.7. Cross-JWT Confusion . . . . . . . . . . . . . . . . . . . 5		2.7. Cross-JWT Confusion . . . . . . . . . . . . . . . . . . . 5
	3. Best Practices . . . . . . . . . . . . . . . . . . . . . . . 6		3. Best Practices . . . . . . . . . . . . . . . . . . . . . . . 6
	3.1. Perform Algorithm Verification . . . . . . . . . . . . . 6		3.1. Perform Algorithm Verification . . . . . . . . . . . . . 6
	3.2. Use Appropriate Algorithms . . . . . . . . . . . . . . . 6		3.2. Use Appropriate Algorithms . . . . . . . . . . . . . . . 6
	3.3. Validate All Cryptographic Operations . . . . . . . . . . 6		3.3. Validate All Cryptographic Operations . . . . . . . . . . 7
	3.4. Validate Cryptographic Inputs . . . . . . . . . . . . . . 7		3.4. Validate Cryptographic Inputs . . . . . . . . . . . . . . 7
	3.5. Ensure Cryptographic Keys have Sufficient Entropy . . . . 7		3.5. Ensure Cryptographic Keys have Sufficient Entropy . . . . 7
	3.6. Use UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . 7		3.6. Avoid Length-Dependent Encryption Inputs . . . . . . . . 7
	3.7. Validate Issuer and Subject . . . . . . . . . . . . . . . 7		3.7. Use UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . 8
	3.8. Use and Validate Audience . . . . . . . . . . . . . . . . 8		3.8. Validate Issuer and Subject . . . . . . . . . . . . . . . 8
	3.9. Use Explicit Typing . . . . . . . . . . . . . . . . . . . 8		3.9. Use and Validate Audience . . . . . . . . . . . . . . . . 8
	3.10. Use Mutually Exclusive Validation Rules for Different		3.10. Do Not Trust Received Claims . . . . . . . . . . . . . . 8
	Kinds of JWTs . . . . . . . . . . . . . . . . . . . . . . 8		3.11. Use Explicit Typing . . . . . . . . . . . . . . . . . . . 9
	4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9		3.12. Use Mutually Exclusive Validation Rules for Different
	5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9		Kinds of JWTs . . . . . . . . . . . . . . . . . . . . . . 9
	6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9		4. Security Considerations . . . . . . . . . . . . . . . . . . . 10
	6.1. Normative References . . . . . . . . . . . . . . . . . . 10		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
	6.2. Informative References . . . . . . . . . . . . . . . . . 10		6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
	Appendix A. Document History . . . . . . . . . . . . . . . . . . 12		7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
	A.1. draft-ietf-oauth-jwt-bcp-01 . . . . . . . . . . . . . . . 12		7.1. Normative References . . . . . . . . . . . . . . . . . . 11
	A.2. draft-ietf-oauth-jwt-bcp-00 . . . . . . . . . . . . . . . 12		7.2. Informative References . . . . . . . . . . . . . . . . . 11
	A.3. draft-sheffer-oauth-jwt-bcp-01 . . . . . . . . . . . . . 12		Appendix A. Document History . . . . . . . . . . . . . . . . . . 13
	A.4. draft-sheffer-oauth-jwt-bcp-00 . . . . . . . . . . . . . 12		A.1. draft-ietf-oauth-jwt-bcp-02 . . . . . . . . . . . . . . . 13
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12		A.2. draft-ietf-oauth-jwt-bcp-01 . . . . . . . . . . . . . . . 13
			A.3. draft-ietf-oauth-jwt-bcp-00 . . . . . . . . . . . . . . . 13
			A.4. draft-sheffer-oauth-jwt-bcp-01 . . . . . . . . . . . . . 13
			A.5. draft-sheffer-oauth-jwt-bcp-00 . . . . . . . . . . . . . 13
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
	1. Introduction		1. Introduction
	JSON Web Tokens, also known as JWTs [RFC7519], are URL-safe JSON-		JSON Web Tokens, also known as JWTs [RFC7519], are URL-safe JSON-
	based security tokens that contain a set of claims that can be signed		based security tokens that contain a set of claims that can be signed
	and/or encrypted. The JWT specification has seen rapid adoption		and/or encrypted. The JWT specification has seen rapid adoption
	because it encapsulates security-relevant information in one, easy to		because it encapsulates security-relevant information in one, easy to
	protect location, and because it is easy to implement using widely-		protect location, and because it is easy to implement using widely-
	available tools. One application area in which JWTs are commonly		available tools. One application area in which JWTs are commonly
	used is representing digital identity information, such as OpenID		used is representing digital identity information, such as OpenID
	skipping to change at page 5, line 7 ¶		skipping to change at page 5, line 7 ¶
	In addition, some applications sign tokens using a weak symmetric key		In addition, some applications sign tokens using a weak symmetric key
	and a keyed MAC algorithm such as "HS256". In most cases, these keys		and a keyed MAC algorithm such as "HS256". In most cases, these keys
	are human memorable passwords that are vulnerable to dictionary		are human memorable passwords that are vulnerable to dictionary
	attacks [Langkemper].		attacks [Langkemper].
	For mitigations, see Section 3.5.		For mitigations, see Section 3.5.
	2.3. Multiplicity of JSON encodings		2.3. Multiplicity of JSON encodings
	Many practitioners are not aware that JSON [RFC7159] allows several		Previous versions of the JSON format [RFC8259] allowed several
	different character encodings: UTF-8, UTF-16 and UTF-32. As a		different character encodings: UTF-8, UTF-16 and UTF-32. This is not
	result, the JWT might be misinterpreted by its recipient.		the case anymore, with the latest standard only allowing UTF-8.
			However older implementations may result in the JWT being
			misinterpreted by its recipient.
	For mitigations, see Section 3.6.		For mitigations, see Section 3.7.
	2.4. Incorrect Composition of Encryption and Signature		2.4. Incorrect Composition of Encryption and Signature
	Some libraries that decrypt a JWE-encrypted JWT to obtain a JWS-		Some libraries that decrypt a JWE-encrypted JWT to obtain a JWS-
	signed object do not always validate the internal signature.		signed object do not always validate the internal signature.
	For mitigations, see Section 3.3.		For mitigations, see Section 3.3.
	2.5. Insecure Use of Elliptic Curve Encryption		2.5. Insecure Use of Elliptic Curve Encryption
	skipping to change at page 5, line 39 ¶		skipping to change at page 5, line 41 ¶
	For mitigations, see Section 3.4.		For mitigations, see Section 3.4.
	2.6. Substitution Attacks		2.6. Substitution Attacks
	There are attacks in which one recipient will have a JWT intended for		There are attacks in which one recipient will have a JWT intended for
	it and attempt to use it at a different recipient that it was not		it and attempt to use it at a different recipient that it was not
	intended for. If not caught, these attacks can result in the		intended for. If not caught, these attacks can result in the
	attacker gaining access to resources that it is not entitled to		attacker gaining access to resources that it is not entitled to
	access.		access.
	For mitigations, see Section 3.7 and Section 3.8.		For mitigations, see Section 3.8 and Section 3.9.
	2.7. Cross-JWT Confusion		2.7. Cross-JWT Confusion
	As JWTs are being used by more different protocols in diverse		As JWTs are being used by more different protocols in diverse
	application areas, it becomes increasingly important to prevent cases		application areas, it becomes increasingly important to prevent cases
	of JWT tokens that have been issued for one purpose being subverted		of JWT tokens that have been issued for one purpose being subverted
	and used for another. Note that this is a specific type of		and used for another. Note that this is a specific type of
	substitution attack. If the JWT could be used in an application		substitution attack. If the JWT could be used in an application
	context in which it could be confused with other kinds of JWTs, then		context in which it could be confused with other kinds of JWTs, then
	mitigations MUST be employed to prevent these substitution attacks.		mitigations MUST be employed to prevent these substitution attacks.
	For mitigations, see Section 3.7, Section 3.8, Section 3.9, and		For mitigations, see Section 3.8, Section 3.9, Section 3.11, and
	Section 3.10.		Section 3.12.
	3. Best Practices		3. Best Practices
	The best practices listed below should be applied by practitioners to		The best practices listed below should be applied by practitioners to
	mitigate the threats listed in the preceding section.		mitigate the threats listed in the preceding section.
	3.1. Perform Algorithm Verification		3.1. Perform Algorithm Verification
	Libraries MUST enable the caller to specify a supported set of		Libraries MUST enable the caller to specify a supported set of
	algorithms and MUST NOT use any other algorithms when performing		algorithms and MUST NOT use any other algorithms when performing
	skipping to change at page 6, line 44 ¶		skipping to change at page 6, line 47 ¶
	That said, if a JWT is cryptographically protected by a transport		That said, if a JWT is cryptographically protected by a transport
	layer, such as TLS using cryptographically current algorithms, there		layer, such as TLS using cryptographically current algorithms, there
	may be no need to apply another layer of cryptographic protections to		may be no need to apply another layer of cryptographic protections to
	the JWT. In such cases, the use of the "none" algorithm can be		the JWT. In such cases, the use of the "none" algorithm can be
	perfectly acceptable. JWTs using "none" are often used in		perfectly acceptable. JWTs using "none" are often used in
	application contexts in which the content is optionally signed; then		application contexts in which the content is optionally signed; then
	the URL-safe claims representation and processing can be the same in		the URL-safe claims representation and processing can be the same in
	both the signed and unsigned cases.		both the signed and unsigned cases.
			Applications SHOULD follow these algorithm-specific recommendations:
			- Avoid all RSA-PKCS1 v1.5 encryption algorithms, preferring RSA-
			OAEP.
			- ECDSA signatures require a unique random value for every message
			that is signed. If even just a few bits of the random value are
			predictable across multiple messages then the security of the
			signature scheme may be compromised. In the worst case, the
			private key may be recoverable by an attacker. To counter these
			attacks, JWT libraries SHOULD implement ECDSA using the
			deterministic approach defined in [RFC6979]. This approach is
			completely compatible with existing ECDSA verifiers and so can be
			implemented without new algorithm identifiers being required.
	3.3. Validate All Cryptographic Operations		3.3. Validate All Cryptographic Operations
	All cryptographic operations used in the JWT MUST be validated and		All cryptographic operations used in the JWT MUST be validated and
	the entire JWT MUST be rejected if any of them fail to validate.		the entire JWT MUST be rejected if any of them fail to validate.
	This is true not only of JWTs with a single set of Header Parameters		This is true not only of JWTs with a single set of Header Parameters
	but also for Nested JWTs, in which both outer and inner operations		but also for Nested JWTs, in which both outer and inner operations
	MUST be validated using the keys and algorithms supplied by the		MUST be validated using the keys and algorithms supplied by the
	application.		application.
	3.4. Validate Cryptographic Inputs		3.4. Validate Cryptographic Inputs
	Some cryptographic operations, such as Elliptic Curve Diffie-Hellman		Some cryptographic operations, such as Elliptic Curve Diffie-Hellman
	key agreement ("ECDH-ES") take inputs that may contain invalid		key agreement ("ECDH-ES") take inputs that may contain invalid
	values, such as points not on the specified elliptic curve or other		values, such as points not on the specified elliptic curve or other
	invalid points. Either the JWS/JWE library itself must validate		invalid points (see e.g. [Valenta], Sec. 7.1). Either the JWS/JWE
	these inputs before using them or it must use underlying		library itself must validate these inputs before using them or it
	cryptographic libraries that do so (or both!).		must use underlying cryptographic libraries that do so (or both!).
			ECDH-ES ephemeral public key (epk) inputs should be validated
			according to the recipient's chosen elliptic curve. For the NIST
			prime-order curves P-256, P-384 and P-521, validation MUST be
			performed according to Section 5.6.2.3.4 "ECC Partial Public-Key
			Validation Routine" of NIST Special Publication 800-56A revision 3
			[nist-sp-800-56a-r3].
	3.5. Ensure Cryptographic Keys have Sufficient Entropy		3.5. Ensure Cryptographic Keys have Sufficient Entropy
	The Key Entropy and Random Values advice in Section 10.1 of [RFC7515]		The Key Entropy and Random Values advice in Section 10.1 of [RFC7515]
	and the Password Considerations in Section 8.8 of [RFC7518] MUST be		and the Password Considerations in Section 8.8 of [RFC7518] MUST be
	followed. In particular, human-memorizable passwords MUST NOT be		followed. In particular, human-memorizable passwords MUST NOT be
	directly used as the key to a keyed-MAC algorithm such as "HS256".		directly used as the key to a keyed-MAC algorithm such as "HS256".
	3.6. Use UTF-8		3.6. Avoid Length-Dependent Encryption Inputs
			Many encryption algorithms leak information about the length of the
			plaintext, with a varying amount of leakage depending on the
			algorithm and mode of operation. Sensitive information, such as
			passwords, SHOULD be padded before being encrypted. It is
			RECOMMENDED to avoid any compression of data before encryption since
			such compression often reveals information about the plaintext.
			3.7. Use UTF-8
	[RFC7515], [RFC7516], and [RFC7519] all specify that UTF-8 be used		[RFC7515], [RFC7516], and [RFC7519] all specify that UTF-8 be used
	for encoding and decoding JSON used in Header Parameters and JWT		for encoding and decoding JSON used in Header Parameters and JWT
	Claims Sets. Implementations and applications MUST do this, and not		Claims Sets. This is also in line with the latest JSON specification
	use other Unicode encodings for these purposes.		[RFC8259]. Implementations and applications MUST do this, and not
			use or admit the use of other Unicode encodings for these purposes.
	3.7. Validate Issuer and Subject		3.8. Validate Issuer and Subject
	When a JWT contains an "iss" (issuer) claim, the application MUST		When a JWT contains an "iss" (issuer) claim, the application MUST
	validate that the cryptographic keys used for the cryptographic		validate that the cryptographic keys used for the cryptographic
	operations in the JWT belong to the issuer. If they do not, the		operations in the JWT belong to the issuer. If they do not, the
	application MUST reject the JWT.		application MUST reject the JWT.
	The means of determining the keys owned by an issuer is application-		The means of determining the keys owned by an issuer is application-
	specific. As one example, OpenID Connect [OpenID.Core] issuer values		specific. As one example, OpenID Connect [OpenID.Core] issuer values
	are "https" URLs that reference a JSON metadata document that		are "https" URLs that reference a JSON metadata document that
	contains a "jwks_uri" value that is an "https" URL from which the		contains a "jwks_uri" value that is an "https" URL from which the
	skipping to change at page 8, line 5 ¶		skipping to change at page 8, line 37 ¶
	mechanism is used by [I-D.ietf-oauth-discovery]. Other applications		mechanism is used by [I-D.ietf-oauth-discovery]. Other applications
	may use different means of binding keys to issuers.		may use different means of binding keys to issuers.
	Similarly, when the JWT contains a "sub" (subject) claim, the		Similarly, when the JWT contains a "sub" (subject) claim, the
	application MUST validate that the subject value corresponds to a		application MUST validate that the subject value corresponds to a
	valid subject and/or issuer/subject pair at the application. This		valid subject and/or issuer/subject pair at the application. This
	may include confirming that the issuer is trusted by the application.		may include confirming that the issuer is trusted by the application.
	If the issuer, subject, or the pair are invalid, the application MUST		If the issuer, subject, or the pair are invalid, the application MUST
	reject the JWT.		reject the JWT.
	3.8. Use and Validate Audience		3.9. Use and Validate Audience
	If the same issuer can issue JWTs that are intended for use by more		If the same issuer can issue JWTs that are intended for use by more
	than one relying party or application, the JWT MUST contain an "aud"		than one relying party or application, the JWT MUST contain an "aud"
	(audience) claim that can be used to determine whether the JWT is		(audience) claim that can be used to determine whether the JWT is
	being used by an intended party or was substituted by an attacker at		being used by an intended party or was substituted by an attacker at
	an unintended party. Furthermore, the relying party or application		an unintended party. Furthermore, the relying party or application
	MUST validate the audience value and if the audience value is not		MUST validate the audience value and if the audience value is not
	associated with the recipient, it MUST reject the JWT.		present or not associated with the recipient, it MUST reject the JWT.
	3.9. Use Explicit Typing		3.10. Do Not Trust Received Claims
			The "kid" (key ID) header is used by the relying application to
			perform key lookup. Applications should ensure that this does not
			create SQL or LDAP injection vulnerabilities.
			Similarly, blindly following a "jku" (JWK set URL) header, which may
			contain an arbitrary URL, could result in server-side request forgery
			(SSRF) attacks.
			3.11. Use Explicit Typing
	Confusion of one kind of JWT for another can be prevented by having		Confusion of one kind of JWT for another can be prevented by having
	all the kinds of JWTs that could otherwise potentially be confused		all the kinds of JWTs that could otherwise potentially be confused
	include an explicit JWT type value and include checking the type		include an explicit JWT type value and include checking the type
	value in their validation rules. Explicit JWT typing is accomplished		value in their validation rules. Explicit JWT typing is accomplished
	by using the "typ" header parameter. For instance, the		by using the "typ" header parameter. For instance, the
	[I-D.ietf-secevent-token] specification uses the "application/		[I-D.ietf-secevent-token] specification uses the "application/
	secevent+jwt" media type to perform explicit typing of Security Event		secevent+jwt" media type to perform explicit typing of Security Event
	Tokens (SETs).		Tokens (SETs).
	skipping to change at page 8, line 45 ¶		skipping to change at page 9, line 39 ¶
	parameter containing the explicit type value MUST be present in the		parameter containing the explicit type value MUST be present in the
	inner JWT of the Nested JWT (the JWT whose payload is the JWT Claims		inner JWT of the Nested JWT (the JWT whose payload is the JWT Claims
	Set). The same "typ" header parameter value MAY be present in the		Set). The same "typ" header parameter value MAY be present in the
	outer JWT as well, to explicitly type the entire Nested JWT.		outer JWT as well, to explicitly type the entire Nested JWT.
	Note that the use of explicit typing may not achieve disambiguation		Note that the use of explicit typing may not achieve disambiguation
	from existing kinds of JWTs, as the validation rules for existing		from existing kinds of JWTs, as the validation rules for existing
	kinds JWTs often do not use the "typ" header parameter value.		kinds JWTs often do not use the "typ" header parameter value.
	Explicit typing is RECOMMENDED for new uses of JWTs.		Explicit typing is RECOMMENDED for new uses of JWTs.
	3.10. Use Mutually Exclusive Validation Rules for Different Kinds of		3.12. Use Mutually Exclusive Validation Rules for Different Kinds of
	JWTs		JWTs
	Each application of JWTs defines a profile specifying the required		Each application of JWTs defines a profile specifying the required
	and optional JWT claims and the validation rules associated with		and optional JWT claims and the validation rules associated with
	them. If more than one kind of JWT can be issued by the same issuer,		them. If more than one kind of JWT can be issued by the same issuer,
	the validation rules for those JWTs MUST be written such that they		the validation rules for those JWTs MUST be written such that they
	are mutually exclusive, rejecting JWTs of the wrong kind. To prevent		are mutually exclusive, rejecting JWTs of the wrong kind. To prevent
	substitution of JWTs from one context into another, a number of		substitution of JWTs from one context into another, a number of
	strategies may be employed:		strategies may be employed:
	skipping to change at page 9, line 37 ¶		skipping to change at page 10, line 31 ¶
	- Use different issuers for different kinds of JWTs. Then the		- Use different issuers for different kinds of JWTs. Then the
	distinct "iss" values can be used to segregate the different kinds		distinct "iss" values can be used to segregate the different kinds
	of JWTs.		of JWTs.
	Given the broad diversity of JWT usage and applications, the best		Given the broad diversity of JWT usage and applications, the best
	combination of types, required claims, values, header parameters, key		combination of types, required claims, values, header parameters, key
	usages, and issuers to differentiate among different kinds of JWTs		usages, and issuers to differentiate among different kinds of JWTs
	will, in general, be application specific.		will, in general, be application specific.
	4. IANA Considerations		4. Security Considerations
			This entire document is about security considerations when
			implementing and deploying JSON Web Tokens.
			5. IANA Considerations
	This document requires no IANA actions.		This document requires no IANA actions.
	5. Acknowledgements		6. Acknowledgements
	Thanks to Antonio Sanso for bringing the "ECDH-ES" invalid point		Thanks to Antonio Sanso for bringing the "ECDH-ES" invalid point
	attack to the attention of JWE and JWT implementers. Thanks to Nat		attack to the attention of JWE and JWT implementers. Thanks to Nat
	Sakimura for advocating the use of explicit typing.		Sakimura for advocating the use of explicit typing. Thanks to Neil
			Madden for his numerous comments, and to Carsten Bormann for his
			review.
	6. References		7. References
	6.1. Normative References		7.1. Normative References
	[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,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997, <https://www.rfc-		DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
	editor.org/info/rfc2119>.		editor.org/info/rfc2119>.
	[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data		[RFC6979] Pornin, T., "Deterministic Usage of the Digital Signature
	Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March		Algorithm (DSA) and Elliptic Curve Digital Signature
	2014, <https://www.rfc-editor.org/info/rfc7159>.		Algorithm (ECDSA)", RFC 6979, DOI 10.17487/RFC6979, August
			2013, <https://www.rfc-editor.org/info/rfc6979>.
	[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web		[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
	Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May		Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
	2015, <https://www.rfc-editor.org/info/rfc7515>.		2015, <https://www.rfc-editor.org/info/rfc7515>.
	[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",		[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
	RFC 7516, DOI 10.17487/RFC7516, May 2015,		RFC 7516, DOI 10.17487/RFC7516, May 2015,
	<https://www.rfc-editor.org/info/rfc7516>.		<https://www.rfc-editor.org/info/rfc7516>.
	[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,		[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
	DOI 10.17487/RFC7518, May 2015, <https://www.rfc-		DOI 10.17487/RFC7518, May 2015, <https://www.rfc-
	editor.org/info/rfc7518>.		editor.org/info/rfc7518>.
	[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token		[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
	(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,		(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
	<https://www.rfc-editor.org/info/rfc7519>.		<https://www.rfc-editor.org/info/rfc7519>.
	6.2. Informative References		[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
			Interchange Format", STD 90, RFC 8259,
			DOI 10.17487/RFC8259, December 2017, <https://www.rfc-
			editor.org/info/rfc8259>.
			7.2. Informative References
	[I-D.ietf-oauth-discovery]		[I-D.ietf-oauth-discovery]
	Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0		Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0
	Authorization Server Metadata", draft-ietf-oauth-		Authorization Server Metadata", draft-ietf-oauth-
	discovery-10 (work in progress), March 2018.		discovery-10 (work in progress), March 2018.
	[I-D.ietf-secevent-token]		[I-D.ietf-secevent-token]
	Hunt, P., Jones, M., Denniss, W., and M. Ansari, "Security		Hunt, P., Jones, M., Denniss, W., and M. Ansari, "Security
	Event Token (SET)", draft-ietf-secevent-token-07 (work in		Event Token (SET)", draft-ietf-secevent-token-10 (work in
	progress), March 2018.		progress), May 2018.
	[Langkemper]		[Langkemper]
	Langkemper, S., "Attacking JWT Authentication", September		Langkemper, S., "Attacking JWT Authentication", September
	2016, <https://www.sjoerdlangkemper.nl/2016/09/28/		2016, <https://www.sjoerdlangkemper.nl/2016/09/28/
	attacking-jwt-authentication/>.		attacking-jwt-authentication/>.
			[nist-sp-800-56a-r3]
			Barker, E., Chen, L., Keller, S., Roginsky, A., Vassilev,
			A., and R. Davis, "Recommendation for Pair-Wise Key
			Establishment Schemes Using Discrete Logarithm
			Cryptography, Draft NIST Special Publication 800-56A
			Revision 3", August 2017,
			<https://csrc.nist.gov/CSRC/media/Publications/sp/800-56a/
			rev-3/draft/documents/sp800-56ar3-draft.pdf>.
	[OpenID.Core]		[OpenID.Core]
	Sakimura, N., Bradley, J., Jones, M., Medeiros, B., and C.		Sakimura, N., Bradley, J., Jones, M., Medeiros, B., and C.
	Mortimore, "OpenID Connect Core 1.0", November 2014,		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>.
	[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",		[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
	RFC 6749, DOI 10.17487/RFC6749, October 2012,		RFC 6749, DOI 10.17487/RFC6749, October 2012,
	<https://www.rfc-editor.org/info/rfc6749>.		<https://www.rfc-editor.org/info/rfc6749>.
	[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,		[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
	DOI 10.17487/RFC7517, May 2015, <https://www.rfc-		DOI 10.17487/RFC7517, May 2015, <https://www.rfc-
	editor.org/info/rfc7517>.		editor.org/info/rfc7517>.
	[Sanso] Sanso, A., "Critical Vulnerability Uncovered in JSON		[Sanso] Sanso, A., "Critical Vulnerability Uncovered in JSON
	Encryption", March 2017,		Encryption", March 2017,
	<https://blogs.adobe.com/security/2017/03/critical-		<https://blogs.adobe.com/security/2017/03/critical-
	vulnerability-uncovered-in-json-encryption.html>.		vulnerability-uncovered-in-json-encryption.html>.
			[Valenta] Valenta, L., Sullivan, N., Sanso, A., and N. Heninger, "In
			search of CurveSwap: Measuring elliptic curve
			implementations in the wild", March 2018,
			<https://ia.cr/2018/298>.
	Appendix A. Document History		Appendix A. 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 ]]
	A.1. draft-ietf-oauth-jwt-bcp-01		A.1. draft-ietf-oauth-jwt-bcp-02
			- Implemented WGLC feedback.
			A.2. draft-ietf-oauth-jwt-bcp-01
	- Feedback from Brian Campbell.		- Feedback from Brian Campbell.
	A.2. draft-ietf-oauth-jwt-bcp-00		A.3. draft-ietf-oauth-jwt-bcp-00
	- Initial WG draft. No change from the latest individual version.		- Initial WG draft. No change from the latest individual version.
	A.3. draft-sheffer-oauth-jwt-bcp-01		A.4. draft-sheffer-oauth-jwt-bcp-01
	- Added explicit typing.		- Added explicit typing.
	A.4. draft-sheffer-oauth-jwt-bcp-00		A.5. draft-sheffer-oauth-jwt-bcp-00
	- Initial version.		- Initial version.
	Authors' Addresses		Authors' Addresses
	Yaron Sheffer		Yaron Sheffer
	Intuit		Intuit
	EMail: yaronf.ietf@gmail.com		EMail: yaronf.ietf@gmail.com
End of changes. 33 change blocks.
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