draft-ietf-cose-webauthn-algorithms-08.txt		rfc8812.txt
	COSE Working Group M. Jones		Internet Engineering Task Force (IETF) M. Jones
	Internet-Draft Microsoft		Request for Comments: 8812 Microsoft
	Intended status: Standards Track June 11, 2020		Category: Standards Track August 2020
	Expires: December 13, 2020		ISSN: 2070-1721
	COSE and JOSE Registrations for WebAuthn Algorithms		CBOR Object Signing and Encryption (COSE) and JSON Object Signing and
	draft-ietf-cose-webauthn-algorithms-08		Encryption (JOSE) Registrations for Web Authentication (WebAuthn)
			Algorithms
	Abstract		Abstract
	The W3C Web Authentication (WebAuthn) specification and the FIDO		The W3C Web Authentication (WebAuthn) specification and the FIDO
	Alliance Client to Authenticator Protocol (CTAP) specification use		Alliance FIDO2 Client to Authenticator Protocol (CTAP) specification
	CBOR Object Signing and Encryption (COSE) algorithm identifiers.		use CBOR Object Signing and Encryption (COSE) algorithm identifiers.
	This specification registers the following algorithms in the IANA		This specification registers the following algorithms (which are used
	"COSE Algorithms" registry, which are used by WebAuthn and CTAP		by WebAuthn and CTAP implementations) in the IANA "COSE Algorithms"
	implementations: RSASSA-PKCS1-v1_5 using SHA-256, SHA-384, SHA-512,		registry: RSASSA-PKCS1-v1_5 using SHA-256, SHA-384, SHA-512, and SHA-
	and SHA-1, and ECDSA using the secp256k1 curve and SHA-256. It		1; and Elliptic Curve Digital Signature Algorithm (ECDSA) using the
	registers the secp256k1 elliptic curve in the IANA "COSE Elliptic		secp256k1 curve and SHA-256. It registers the secp256k1 elliptic
	Curves" registry. Also, for use with JSON Object Signing and		curve in the IANA "COSE Elliptic Curves" registry. Also, for use
	Encryption (JOSE), it registers the algorithm ECDSA using the		with JSON Object Signing and Encryption (JOSE), it registers the
	secp256k1 curve and SHA-256 in the IANA "JSON Web Signature and		algorithm ECDSA using the secp256k1 curve and SHA-256 in the IANA
	Encryption Algorithms" registry and the secp256k1 elliptic curve in		"JSON Web Signature and Encryption Algorithms" registry and the
	the IANA "JSON Web Key Elliptic Curve" registry.		secp256k1 elliptic curve in the IANA "JSON Web Key Elliptic Curve"
			registry.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This is an Internet Standards Track document.
	provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering
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	Internet-Drafts are draft documents valid for a maximum of six months		This document is a product of the Internet Engineering Task Force
	and may be updated, replaced, or obsoleted by other documents at any		(IETF). It represents the consensus of the IETF community. It has
	time. It is inappropriate to use Internet-Drafts as reference		received public review and has been approved for publication by the
	material or to cite them other than as "work in progress."		Internet Engineering Steering Group (IESG). Further information on
			Internet Standards is available in Section 2 of RFC 7841.
	This Internet-Draft will expire on December 13, 2020.		Information about the current status of this document, any errata,
			and how to provide feedback on it may be obtained at
			https://www.rfc-editor.org/info/rfc8812.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2020 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
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction
	1.1. Requirements Notation and Conventions . . . . . . . . . . 3		1.1. Requirements Notation and Conventions
	2. RSASSA-PKCS1-v1_5 Signature Algorithm . . . . . . . . . . . . 3		2. RSASSA-PKCS1-v1_5 Signature Algorithm
	3. Using secp256k1 with JOSE and COSE . . . . . . . . . . . . . 4		3. Using secp256k1 with JOSE and COSE
	3.1. JOSE and COSE secp256k1 Curve Key Representations . . . . 5		3.1. JOSE and COSE secp256k1 Curve Key Representations
	3.2. ECDSA Signature with secp256k1 Curve . . . . . . . . . . 5		3.2. ECDSA Signature with secp256k1 Curve
	3.3. Other Uses of the secp256k1 Elliptic Curve . . . . . . . 7		3.3. Other Uses of the secp256k1 Elliptic Curve
	4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		4. IANA Considerations
	4.1. COSE Algorithms Registrations . . . . . . . . . . . . . . 7		4.1. COSE Algorithms Registrations
	4.2. COSE Elliptic Curves Registrations . . . . . . . . . . . 8		4.2. COSE Elliptic Curves Registrations
	4.3. JOSE Algorithms Registrations . . . . . . . . . . . . . . 8		4.3. JOSE Algorithms Registrations
	4.4. JSON Web Key Elliptic Curves Registrations . . . . . . . 9		4.4. JSON Web Key Elliptic Curves Registrations
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 9		5. Security Considerations
	5.1. RSA Key Size Security Considerations . . . . . . . . . . 9		5.1. RSA Key Size Security Considerations
	5.2. RSASSA-PKCS1-v1_5 with SHA-2 Security Considerations . . 9		5.2. RSASSA-PKCS1-v1_5 with SHA-2 Security Considerations
	5.3. RSASSA-PKCS1-v1_5 with SHA-1 Security Considerations . . 9		5.3. RSASSA-PKCS1-v1_5 with SHA-1 Security Considerations
	5.4. secp256k1 Security Considerations . . . . . . . . . . . . 9		5.4. secp256k1 Security Considerations
	6. References . . . . . . . . . . . . . . . . . . . . . . . . . 10		6. References
	6.1. Normative References . . . . . . . . . . . . . . . . . . 10		6.1. Normative References
	6.2. Informative References . . . . . . . . . . . . . . . . . 11		6.2. Informative References
	Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12		Acknowledgements
	Document History . . . . . . . . . . . . . . . . . . . . . . . . 12		Author's Address
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14
	1. Introduction		1. Introduction
	This specification defines how to use several algorithms with CBOR		This specification defines how to use several algorithms with CBOR
	Object Signing and Encryption (COSE) [RFC8152] that are used by		Object Signing and Encryption (COSE) [RFC8152] that are used by
	implementations of the W3C Web Authentication (WebAuthn) [WebAuthn]		implementations of the W3C Web Authentication (WebAuthn) [WebAuthn]
	and FIDO Alliance FIDO2 Client to Authenticator Protocol (CTAP)		and FIDO Alliance FIDO2 Client to Authenticator Protocol (CTAP)
	[CTAP] specifications. This specification registers these algorithms		[CTAP] specifications. This specification registers these algorithms
	in the IANA "COSE Algorithms" registry [IANA.COSE.Algorithms] and		in the IANA "COSE Algorithms" registry [IANA.COSE.Algorithms] and
	registers an elliptic curve in the IANA "COSE Elliptic Curves"		registers an elliptic curve in the IANA "COSE Elliptic Curves"
	skipping to change at page 3, line 12 ¶		skipping to change at line 102 ¶
	corresponding algorithm for use with JSON Object Signing and		corresponding algorithm for use with JSON Object Signing and
	Encryption (JOSE) [RFC7515] in the IANA "JSON Web Signature and		Encryption (JOSE) [RFC7515] in the IANA "JSON Web Signature and
	Encryption Algorithms" registry [IANA.JOSE.Algorithms] and registers		Encryption Algorithms" registry [IANA.JOSE.Algorithms] and registers
	an elliptic curve in the IANA "JSON Web Key Elliptic Curve" registry		an elliptic curve in the IANA "JSON Web Key Elliptic Curve" registry
	[IANA.JOSE.Curves].		[IANA.JOSE.Curves].
	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
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	2. RSASSA-PKCS1-v1_5 Signature Algorithm		2. RSASSA-PKCS1-v1_5 Signature Algorithm
	The RSASSA-PKCS1-v1_5 signature algorithm is defined in [RFC8017].		The RSASSA-PKCS1-v1_5 signature algorithm is defined in [RFC8017].
	The RSASSA-PKCS1-v1_5 signature algorithm is parameterized with a		The RSASSA-PKCS1-v1_5 signature algorithm is parameterized with a
	hash function (h).		hash function (h).
	A key of size 2048 bits or larger MUST be used with these algorithms.		A key of size 2048 bits or larger MUST be used with these algorithms.
	Implementations need to check that the key type is 'RSA' when		Implementations need to check that the key type is 'RSA' when
	creating or verifying a signature.		creating or verifying a signature.
	The RSASSA-PKCS1-v1_5 algorithms specified in this document are in		The RSASSA-PKCS1-v1_5 algorithms specified in this document are in
	the following table.		the following table.
	+-------+---------------+---------+-------------------+-------------+		+=======+========+=========+===================+=============+
	| Name | Value | Hash | Description | Recommended |		| Name | Value | Hash | Description | Recommended |
	+-------+---------------+---------+-------------------+-------------+		+=======+========+=========+===================+=============+
	| RS256 | TBD | SHA-256 | RSASSA-PKCS1-v1_5 | No |		| RS256 | -257 | SHA-256 | RSASSA-PKCS1-v1_5 | No |
	| | (temporary | | using SHA-256 | |		| | | | using SHA-256 | |
	| | assignment | | | |		+-------+--------+---------+-------------------+-------------+
	| | -257 already | | | |		| RS384 | -258 | SHA-384 | RSASSA-PKCS1-v1_5 | No |
	| | in place) | | | |		| | | | using SHA-384 | |
	| RS384 | TBD | SHA-384 | RSASSA-PKCS1-v1_5 | No |		+-------+--------+---------+-------------------+-------------+
	| | (temporary | | using SHA-384 | |		| RS512 | -259 | SHA-512 | RSASSA-PKCS1-v1_5 | No |
	| | assignment | | | |		| | | | using SHA-512 | |
	| | -258 already | | | |		+-------+--------+---------+-------------------+-------------+
	| | in place) | | | |		| RS1 | -65535 | SHA-1 | RSASSA-PKCS1-v1_5 | Deprecated |
	| RS512 | TBD | SHA-512 | RSASSA-PKCS1-v1_5 | No |		| | | | using SHA-1 | |
	| | (temporary | | using SHA-512 | |		+-------+--------+---------+-------------------+-------------+
	| | assignment | | | |
	| | -259 already | | | |
	| | in place) | | | |
	| RS1 | TBD | SHA-1 | RSASSA-PKCS1-v1_5 | Deprecated |
	| | (temporary | | using SHA-1 | |
	| | assignment | | | |
	| | -65535 | | | |
	| | already in | | | |
	| | place) | | | |
	+-------+---------------+---------+-------------------+-------------+
	Table 1: RSASSA-PKCS1-v1_5 Algorithm Values		Table 1: RSASSA-PKCS1-v1_5 Algorithm Values
	Security considerations for use of the first three algorithms are in		Security considerations for use of the first three algorithms are in
	Section 5.2. Security considerations for use of the last algorithm		Section 5.2. Security considerations for use of the last algorithm
	are in Section 5.3.		are in Section 5.3.
	Note that these algorithms are already present in the IANA "JSON Web		Note that these algorithms are already present in the IANA "JSON Web
	Signature and Encryption Algorithms" registry [IANA.JOSE.Algorithms],		Signature and Encryption Algorithms" registry [IANA.JOSE.Algorithms],
	and so these registrations are only for the IANA "COSE Algorithms"		and so these registrations are only for the IANA "COSE Algorithms"
	registry [IANA.COSE.Algorithms].		registry [IANA.COSE.Algorithms].
	3. Using secp256k1 with JOSE and COSE		3. Using secp256k1 with JOSE and COSE
	This section defines algorithm encodings and representations enabling		This section defines algorithm encodings and representations enabling
	the Standards for Efficient Cryptography Group (SECG) elliptic curve		the Standards for Efficient Cryptography Group (SECG) elliptic curve
	secp256k1 [SEC2] to be used for JOSE [RFC7515] and COSE [RFC8152]		secp256k1 [SEC2] to be used for JOSE [RFC7515] and COSE [RFC8152]
	messages.		messages.
	3.1. JOSE and COSE secp256k1 Curve Key Representations		3.1. JOSE and COSE secp256k1 Curve Key Representations
	The Standards for Efficient Cryptography Group (SECG) elliptic curve		The SECG elliptic curve secp256k1 [SEC2] is represented in a JSON Web
	secp256k1 [SEC2] is represented in a JSON Web Key (JWK) [RFC7517]		Key (JWK) [RFC7517] using these values:
	using these values:
	o "kty": "EC"		* "kty": "EC"
	o "crv": "secp256k1"		* "crv": "secp256k1"
	plus the values needed to represent the curve point, as defined in		plus the values needed to represent the curve point, as defined in
	Section 6.2.1 of [RFC7518]. As a compressed point encoding		Section 6.2.1 of [RFC7518]. As a compressed point encoding
	representation is not defined for JWK elliptic curve points, the		representation is not defined for JWK elliptic curve points, the
	uncompressed point encoding defined there MUST be used. The "x" and		uncompressed point encoding defined there MUST be used. The "x" and
	"y" values represented MUST both be exactly 256 bits, with any		"y" values represented MUST both be exactly 256 bits, with any
	leading zeros preserved. Other optional values such as "alg" MAY		leading zeros preserved. Other optional values such as "alg" MAY
	also be present.		also be present.
	It is represented in a COSE_Key [RFC8152] using these values:		It is represented in a COSE_Key [RFC8152] using these values:
	o "kty" (1): "EC2" (2)		* "kty" (1): "EC2" (2)
	o "crv" (-1): "secp256k1" (TBD - requested assignment 8)		* "crv" (-1): "secp256k1" (8)
	plus the values needed to represent the curve point, as defined in		plus the values needed to represent the curve point, as defined in
	Section 13.1.1 of [RFC8152]. Either the uncompressed or compressed		Section 13.1.1 of [RFC8152]. Either the uncompressed or compressed
	point encoding representations defined there can be used. The "x"		point encoding representations defined there can be used. The "x"
	value represented MUST be exactly 256 bits, with any leading zeros		value represented MUST be exactly 256 bits, with any leading zeros
	preserved. If the uncompressed representation is used, the "y" value		preserved. If the uncompressed representation is used, the "y" value
	represented MUST likewise be exactly 256 bits, with any leading zeros		represented MUST likewise be exactly 256 bits, with any leading zeros
	preserved; if the compressed representation is used, the "y" value is		preserved; if the compressed representation is used, the "y" value is
	a boolean value, as specified in Section 13.1.1 of [RFC8152]. Other		a boolean value, as specified in Section 13.1.1 of [RFC8152]. Other
	optional values such as "alg" (3) MAY also be present.		optional values such as "alg" (3) MAY also be present.
	skipping to change at page 6, line 8 ¶		skipping to change at line 203 ¶
	The ECDSA secp256k1 SHA-256 digital signature is generated as		The ECDSA secp256k1 SHA-256 digital signature is generated as
	follows:		follows:
	1. Generate a digital signature of the JWS Signing Input or the COSE		1. Generate a digital signature of the JWS Signing Input or the COSE
	Sig_structure using ECDSA secp256k1 SHA-256 with the desired		Sig_structure using ECDSA secp256k1 SHA-256 with the desired
	private key. The output will be the pair (R, S), where R and S		private key. The output will be the pair (R, S), where R and S
	are 256-bit unsigned integers.		are 256-bit unsigned integers.
	2. Turn R and S into octet sequences in big-endian order, with each		2. Turn R and S into octet sequences in big-endian order, with each
	array being be 32 octets long. The octet sequence		array being 32 octets long. The octet sequence representations
	representations MUST NOT be shortened to omit any leading zero		MUST NOT be shortened to omit any leading zero octets contained
	octets contained in the values.		in the values.
	3. Concatenate the two octet sequences in the order R and then S.		3. Concatenate the two octet sequences in the order R and then S.
	(Note that many ECDSA implementations will directly produce this		(Note that many ECDSA implementations will directly produce this
	concatenation as their output.)		concatenation as their output.)
	4. The resulting 64-octet sequence is the JWS Signature or COSE		4. The resulting 64-octet sequence is the JWS Signature or COSE
	signature value.		signature value.
	Implementations SHOULD use a deterministic algorithm to generate the		Implementations SHOULD use a deterministic algorithm to generate the
	ECDSA nonce, k, such as [RFC6979]. However, in situations where		ECDSA nonce, k, such as the algorithm defined in [RFC6979]. However,
	devices are vulnerable to physical attacks, deterministic ECDSA has		in situations where devices are vulnerable to physical attacks,
	been shown to be susceptible to fault injection attacks [Kudelski17]		deterministic ECDSA has been shown to be susceptible to fault
	[EuroSP18]. Where this is a possibility, implementations SHOULD		injection attacks [KUDELSKI17] [EURO-SP18]. Where this is a
	implement appropriate countermeasures. Where there are specific		possibility, implementations SHOULD implement appropriate
	certification requirements (such as FIPS approval), implementors		countermeasures. Where there are specific certification requirements
	should check whether deterministic ECDSA is an approved nonce		(such as FIPS approval), implementors should check whether
	generation method.		deterministic ECDSA is an approved nonce generation method.
	The ECDSA secp256k1 SHA-256 algorithm specified in this document uses		The ECDSA secp256k1 SHA-256 algorithm specified in this document uses
	these identifiers:		these identifiers:
	+----------+-------------------+----------------------+-------------+		+========+=======+=======================+=============+
	| JOSE Alg | COSE Alg Value | Description | Recommended |		| Name | Value | Description | Recommended |
	| Name | | | |		+========+=======+=======================+=============+
	+----------+-------------------+----------------------+-------------+		| ES256K | -47 | ECDSA using secp256k1 | No |
	| ES256K | TBD (requested | ECDSA using | No |		| | | curve and SHA-256 | |
	| | assignment -47) | secp256k1 curve and | |		+--------+-------+-----------------------+-------------+
	| | | SHA-256 | |
	+----------+-------------------+----------------------+-------------+
	Table 2: ECDSA Algorithm Values		Table 2: ECDSA Algorithm Values
	When using a JWK or COSE_Key for this algorithm, the following checks		When using a JWK or COSE_Key for this algorithm, the following checks
	are made:		are made:
	o The "kty" field MUST be present and it MUST be "EC" for JOSE or		* The "kty" field MUST be present, and it MUST be "EC" for JOSE or
	"EC2" for COSE.		"EC2" for COSE.
	o The "crv" field MUST be present and it MUST represent the		* The "crv" field MUST be present, and it MUST represent the
	"secp256k1" elliptic curve.		"secp256k1" elliptic curve.
	o If the "alg" field is present, it MUST represent the "ES256K"		* If the "alg" field is present, it MUST represent the "ES256K"
	algorithm.		algorithm.
	o If the "key_ops" field is present, it MUST include "sign" when		* If the "key_ops" field is present, it MUST include "sign" when
	creating an ECDSA signature.		creating an ECDSA signature.
	o If the "key_ops" field is present, it MUST include "verify" when		* If the "key_ops" field is present, it MUST include "verify" when
	verifying an ECDSA signature.		verifying an ECDSA signature.
	o If the JWK _use_ field is present, its value MUST be "sig".		* If the JWK "use" field is present, its value MUST be "sig".
	3.3. Other Uses of the secp256k1 Elliptic Curve		3.3. Other Uses of the secp256k1 Elliptic Curve
	This specification defines how to use the secp256k1 curve for ECDSA		This specification defines how to use the secp256k1 curve for ECDSA
	signatures for both JOSE and COSE implementations. While in theory,		signatures for both JOSE and COSE implementations. While in theory
	the curve could also be used for ECDH-ES key agreement, it is beyond		the curve could also be used for ECDH-ES key agreement, it is beyond
	the scope of this specification to state whether this is or is not		the scope of this specification to state whether this is or is not
	advisable. Thus, whether to recommend its use with ECDH-ES is left		advisable. Thus, whether or not to recommend its use with ECDH-ES is
	for experts to decide in future specifications.		left for experts to decide in future specifications.
	When used for ECDSA, the secp256k1 curve MUST be used only with the		When used for ECDSA, the secp256k1 curve MUST be used only with the
	"ES256K" algorithm identifier and not any others, including not with		"ES256K" algorithm identifier and not any others, including not with
	the COSE "ES256" identifier. Note that the "ES256K" algorithm		the COSE "ES256" identifier. Note that the "ES256K" algorithm
	identifier needed to be introduced for JOSE to sign with the		identifier needed to be introduced for JOSE to sign with the
	secp256k1 curve because the JOSE "ES256" algorithm is defined to be		secp256k1 curve because the JOSE "ES256" algorithm is defined to be
	used only with the P-256 curve. The COSE treatment of how to sign		used only with the P-256 curve. The COSE treatment of how to sign
	with secp256k1 is intentionally parallel to that for JOSE, where the		with secp256k1 is intentionally parallel to that for JOSE, where the
	secp256k1 curve MUST be used with the "ES256K" algorithm identifier.		secp256k1 curve MUST be used with the "ES256K" algorithm identifier.
	4. IANA Considerations		4. IANA Considerations
	4.1. COSE Algorithms Registrations		4.1. COSE Algorithms Registrations
	This section registers the following values in the IANA "COSE		IANA has registered the following values in the "COSE Algorithms"
	Algorithms" registry [IANA.COSE.Algorithms].		registry [IANA.COSE.Algorithms].
	o Name: RS256		Name: RS256
	o Value: TBD (temporary assignment -257 already in place)		Value: -257
	o Description: RSASSA-PKCS1-v1_5 using SHA-256		Description: RSASSA-PKCS1-v1_5 using SHA-256
	o Reference: Section 2 of this document		Change Controller: IESG
	o Recommended: No		Reference: Section 2 of RFC 8812
			Recommended: No
	o Name: RS384		Name: RS384
	o Value: TBD (temporary assignment -258 already in place)		Value: -258
	o Description: RSASSA-PKCS1-v1_5 using SHA-384		Description: RSASSA-PKCS1-v1_5 using SHA-384
	o Reference: Section 2 of this document		Change Controller: IESG
	o Recommended: No		Reference: Section 2 of RFC 8812
	o Name: RS512		Recommended: No
	o Value: TBD (temporary assignment -259 already in place)
	o Description: RSASSA-PKCS1-v1_5 using SHA-512
	o Reference: Section 2 of this document
	o Recommended: No
	o Name: RS1		Name: RS512
	o Value: TBD (temporary assignment -65535 already in place)		Value: -259
	o Description: RSASSA-PKCS1-v1_5 using SHA-1		Description: RSASSA-PKCS1-v1_5 using SHA-512
	o Reference: Section 2 of this document		Change Controller: IESG
	o Recommended: Deprecated		Reference: Section 2 of RFC 8812
			Recommended: No
	o Name: ES256K		Name: RS1
	o Value: TBD (requested assignment -47)		Value: -65535
	o Description: ECDSA using secp256k1 curve and SHA-256		Description: RSASSA-PKCS1-v1_5 using SHA-1
	o Reference: Section 3.2 of this document		Change Controller: IESG
	o Recommended: No		Reference: Section 2 of RFC 8812
			Recommended: Deprecated
			Name: ES256K
			Value: -47
			Description: ECDSA using secp256k1 curve and SHA-256
			Change Controller: IESG
			Reference: Section 3.2 of RFC 8812
			Recommended: No
	4.2. COSE Elliptic Curves Registrations		4.2. COSE Elliptic Curves Registrations
	This section registers the following value in the IANA "COSE Elliptic		IANA has registered the following value in the "COSE Elliptic Curves"
	Curves" registry [IANA.COSE.Curves].		registry [IANA.COSE.Curves].
	o Name: secp256k1		Name: secp256k1
	o Value: TBD (requested assignment 8)		Value: 8
	o Key Type: EC2		Key Type: EC2
	o Description: SECG secp256k1 curve		Description: SECG secp256k1 curve
	o Change Controller: IESG		Change Controller: IESG
	o Reference: Section 3.1 of [[ this specification ]]		Reference: Section 3.1 of RFC 8812
	o Recommended: No		Recommended: No
	4.3. JOSE Algorithms Registrations		4.3. JOSE Algorithms Registrations
	This section registers the following value in the IANA "JSON Web		IANA has registered the following value in the "JSON Web Signature
	Signature and Encryption Algorithms" registry [IANA.JOSE.Algorithms].		and Encryption Algorithms" registry [IANA.JOSE.Algorithms].
	o Algorithm Name: ES256K		Algorithm Name: ES256K
	o Algorithm Description: ECDSA using secp256k1 curve and SHA-256		Algorithm Description: ECDSA using secp256k1 curve and SHA-256
	o Algorithm Usage Locations: alg		Algorithm Usage Location(s): alg
	o JOSE Implementation Requirements: Optional		JOSE Implementation Requirements: Optional
	o Change Controller: IESG		Change Controller: IESG
	o Reference: Section 3.2 of [[ this specification ]]		Reference: Section 3.2 of RFC 8812
	o Algorithm Analysis Document(s): [SEC2]		Algorithm Analysis Document(s): [SEC2]
	4.4. JSON Web Key Elliptic Curves Registrations		4.4. JSON Web Key Elliptic Curves Registrations
	This section registers the following value in the IANA "JSON Web Key		IANA has registered the following value in the "JSON Web Key Elliptic
	Elliptic Curve" registry [IANA.JOSE.Curves].		Curve" registry [IANA.JOSE.Curves].
	o Curve Name: secp256k1		Curve Name: secp256k1
	o Curve Description: SECG secp256k1 curve		Curve Description: SECG secp256k1 curve
	o JOSE Implementation Requirements: Optional		JOSE Implementation Requirements: Optional
	o Change Controller: IESG		Change Controller: IESG
	o Specification Document(s): Section 3.1 of [[ this specification ]]		Specification Document(s): Section 3.1 of RFC 8812
	5. Security Considerations		5. Security Considerations
	5.1. RSA Key Size Security Considerations		5.1. RSA Key Size Security Considerations
	The security considerations on key sizes for RSA algorithms from		The security considerations on key sizes for RSA algorithms from
	Section 6.1 of [RFC8230] also apply to the RSA algorithms in this		Section 6.1 of [RFC8230] also apply to the RSA algorithms in this
	specification.		specification.
	5.2. RSASSA-PKCS1-v1_5 with SHA-2 Security Considerations		5.2. RSASSA-PKCS1-v1_5 with SHA-2 Security Considerations
	skipping to change at page 9, line 42 ¶		skipping to change at line 379 ¶
	5.3. RSASSA-PKCS1-v1_5 with SHA-1 Security Considerations		5.3. RSASSA-PKCS1-v1_5 with SHA-1 Security Considerations
	The security considerations on the use of the SHA-1 hash function		The security considerations on the use of the SHA-1 hash function
	from [RFC6194] apply in this specification. For that reason, the		from [RFC6194] apply in this specification. For that reason, the
	"RS1" algorithm is registered as "Deprecated". Likewise, the		"RS1" algorithm is registered as "Deprecated". Likewise, the
	exponent restrictions described in Section 8.3 of [RFC7518] also		exponent restrictions described in Section 8.3 of [RFC7518] also
	apply.		apply.
	A COSE algorithm identifier for this algorithm is nonetheless being		A COSE algorithm identifier for this algorithm is nonetheless being
	registered because deployed TPMs continue to use it, and therefore		registered because deployed Trusted Platform Modules (TPMs) continue
	WebAuthn implementations need a COSE algorithm identifier for "RS1"		to use it; therefore, WebAuthn implementations need a COSE algorithm
	when TPM attestations using this algorithm are being represented.		identifier for "RS1" when TPM attestations using this algorithm are
	New COSE applications and protocols MUST NOT use this algorithm.		being represented. New COSE applications and protocols MUST NOT use
			this algorithm.
	5.4. secp256k1 Security Considerations		5.4. secp256k1 Security Considerations
	Care should be taken that a secp256k1 key is not mistaken for a P-256		Care should be taken that a secp256k1 key is not mistaken for a P-256
	[RFC7518] key, given that their representations are the same except		[RFC7518] key, given that their representations are the same except
	for the "crv" value. As described in Section 8.1.1 of [RFC8152], we		for the "crv" value. As described in Section 8.1.1 of [RFC8152], we
	currently do not have any way to deal with this attack except to		currently do not have any way to deal with this attack except to
	restrict the set of curves that can be used.		restrict the set of curves that can be used.
	The procedures and security considerations described in the [SEC1],		The procedures and security considerations described in the [SEC1],
	skipping to change at page 10, line 25 ¶		skipping to change at line 411 ¶
	There are theoretical weaknesses with this curve that could result in		There are theoretical weaknesses with this curve that could result in
	future attacks. While these potential weaknesses are not unique to		future attacks. While these potential weaknesses are not unique to
	this curve, they are the reason that this curve is registered as		this curve, they are the reason that this curve is registered as
	"Recommended: No".		"Recommended: No".
	6. References		6. References
	6.1. Normative References		6.1. Normative References
	[DSS] National Institute of Standards and Technology (NIST),		[DSS] National Institute of Standards and Technology (NIST),
	"Digital Signature Standard (DSS)", FIPS PUB 186-4, July		"Digital Signature Standard (DSS)", FIPS PUB 186-4,
	2013, <http://nvlpubs.nist.gov/nistpubs/FIPS/		DOI 10.6028/NIST.FIPS.186-4, July 2013,
	NIST.FIPS.186-4.pdf>.		<https://doi.org/10.6028/NIST.FIPS.186-4>.
	[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,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security		[RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security
	Considerations for the SHA-0 and SHA-1 Message-Digest		Considerations for the SHA-0 and SHA-1 Message-Digest
	Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011,		Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011,
	<https://www.rfc-editor.org/info/rfc6194>.		<https://www.rfc-editor.org/info/rfc6194>.
	skipping to change at page 11, line 25 ¶		skipping to change at line 457 ¶
	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>.
	[RFC8230] Jones, M., "Using RSA Algorithms with CBOR Object Signing		[RFC8230] Jones, M., "Using RSA Algorithms with CBOR Object Signing
	and Encryption (COSE) Messages", RFC 8230,		and Encryption (COSE) Messages", RFC 8230,
	DOI 10.17487/RFC8230, September 2017,		DOI 10.17487/RFC8230, September 2017,
	<https://www.rfc-editor.org/info/rfc8230>.		<https://www.rfc-editor.org/info/rfc8230>.
	[SEC1] Standards for Efficient Cryptography Group, "SEC 1:		[SEC1] Standards for Efficient Cryptography Group, "SEC 1:
	Elliptic Curve Cryptography", Version 2.0, May 2009,		Elliptic Curve Cryptography", Version 2.0, May 2009,
	<http://www.secg.org/sec1-v2.pdf>.		<https://www.secg.org/sec1-v2.pdf>.
	[SEC2] Standards for Efficient Cryptography Group, "SEC 2:		[SEC2] Standards for Efficient Cryptography Group, "SEC 2:
	Recommended Elliptic Curve Domain Parameters",		Recommended Elliptic Curve Domain Parameters",
	Version 2.0, January 2010,		Version 2.0, January 2010,
	<http://www.secg.org/sec2-v2.pdf>.		<https://www.secg.org/sec2-v2.pdf>.
	6.2. Informative References		6.2. Informative References
	[CTAP] Brand, C., Czeskis, A., Ehrensvaerd, J., Jones, M., Kumar,		[CTAP] Brand, C., Czeskis, A., Ehrensvärd, J., Jones, M., Kumar,
	A., Lindemann, R., Powers, A., and J. Verrept, "Client to		A., Lindemann, R., Powers, A., and J. Verrept, "Client to
	Authenticator Protocol (CTAP)", FIDO Alliance Proposed		Authenticator Protocol (CTAP)", FIDO Alliance Proposed
	Standard, January 2019, <https://fidoalliance.org/specs/		Standard, January 2019, <https://fidoalliance.org/specs/
	fido-v2.0-ps-20190130/fido-client-to-authenticator-		fido-v2.0-ps-20190130/fido-client-to-authenticator-
	protocol-v2.0-ps-20190130.html>.		protocol-v2.0-ps-20190130.html>.
	[EuroSP18]		[EURO-SP18]
	Poddebniak, D., Somorovsky, J., Schinzel, S., Lochter, M.,		Poddebniak, D., Somorovsky, J., Schinzel, S., Lochter, M.,
	and P. Roesler, "Attacking Deterministic Signature Schemes		and P. Rösler, "Attacking Deterministic Signature Schemes
	using Fault Attacks", IEEE European Symposium on Security		using Fault Attacks", 2018 IEEE European Symposium on
	and Privacy (EuroS&P) 2018, April 2018,		Security and Privacy (EuroS&P),
	<https://eprint.iacr.org/2017/1014.pdf>.		DOI 10.1109/EuroSP.2018.00031, April 2018,
			<https://ieeexplore.ieee.org/document/8406609>.
	[IANA.COSE.Algorithms]		[IANA.COSE.Algorithms]
	IANA, "COSE Algorithms",		IANA, "COSE Algorithms",
	<https://www.iana.org/assignments/cose/		<https://www.iana.org/assignments/cose>.
	cose.xhtml#algorithms>.
	[IANA.COSE.Curves]		[IANA.COSE.Curves]
	IANA, "COSE Elliptic Curves",		IANA, "COSE Elliptic Curves",
	<https://www.iana.org/assignments/cose/		<https://www.iana.org/assignments/cose>.
	cose.xhtml#elliptic-curves>.
	[IANA.JOSE.Algorithms]		[IANA.JOSE.Algorithms]
	IANA, "JSON Web Signature and Encryption Algorithms",		IANA, "JSON Web Signature and Encryption Algorithms",
	<https://www.iana.org/assignments/jose/jose.xhtml#web-		<https://www.iana.org/assignments/jose>.
	signature-encryption-algorithms>.
	[IANA.JOSE.Curves]		[IANA.JOSE.Curves]
	IANA, "JSON Web Key Elliptic Curve",		IANA, "JSON Web Key Elliptic Curve",
	<https://www.iana.org/assignments/jose/jose.xhtml#web-key-		<https://www.iana.org/assignments/jose>.
	elliptic-curve>.
	[Kudelski17]		[KUDELSKI17]
	Romailler, Y., "How to defeat Ed25519 and EdDSA using		Romailler, Y., "How to Defeat Ed25519 and EdDSA Using
	faults", October 2017,		Faults", Kudelski Security Research, October 2017,
	<https://research.kudelskisecurity.com/2017/10/04/		<https://research.kudelskisecurity.com/2017/10/04/
	defeating-eddsa-with-faults/>.		defeating-eddsa-with-faults/>.
	[RFC6979] Pornin, T., "Deterministic Usage of the Digital Signature		[RFC6979] Pornin, T., "Deterministic Usage of the Digital Signature
	Algorithm (DSA) and Elliptic Curve Digital Signature		Algorithm (DSA) and Elliptic Curve Digital Signature
	Algorithm (ECDSA)", RFC 6979, DOI 10.17487/RFC6979, August		Algorithm (ECDSA)", RFC 6979, DOI 10.17487/RFC6979, August
	2013, <https://www.rfc-editor.org/info/rfc6979>.		2013, <https://www.rfc-editor.org/info/rfc6979>.
	[WebAuthn]		[WebAuthn] Balfanz, D., Czeskis, A., Hodges, J., Jones, J.C., Jones,
	Balfanz, D., Czeskis, A., Hodges, J., Jones, J., Jones,
	M., Kumar, A., Liao, A., Lindemann, R., and E. Lundberg,		M., Kumar, A., Liao, A., Lindemann, R., and E. Lundberg,
	"Web Authentication: An API for accessing Public Key		"Web Authentication: An API for accessing Public Key
	Credentials - Level 1", World Wide Web Consortium		Credentials - Level 1", W3C Recommendation, March 2019,
	(W3C) Recommendation, March 2019,
	<https://www.w3.org/TR/2019/REC-webauthn-1-20190304/>.		<https://www.w3.org/TR/2019/REC-webauthn-1-20190304/>.
	Acknowledgements		Acknowledgements
	Thanks to Roman Danyliw, Linda Dunbar, Stephen Farrell, John Fontana,		Thanks to Roman Danyliw, Linda Dunbar, Stephen Farrell, John Fontana,
	Jeff Hodges, Kevin Jacobs, J.C. Jones, Benjamin Kaduk, Murray		Jeff Hodges, Kevin Jacobs, J.C. Jones, Benjamin Kaduk, Murray
	Kucherawy, Neil Madden, John Mattsson, Matthew Miller, Tony Nadalin,		Kucherawy, Neil Madden, John Mattsson, Matthew Miller, Tony Nadalin,
	Matt Palmer, Eric Rescorla, Rich Salz, Jim Schaad, Goeran Selander,		Matt Palmer, Eric Rescorla, Rich Salz, Jim Schaad, Goeran Selander,
	Wendy Seltzer, Sean Turner, and Samuel Weiler for their roles in		Wendy Seltzer, Sean Turner, and Samuel Weiler for their roles in
	registering these algorithm identifiers.		registering these algorithm identifiers.
	Document History
	[[ to be removed by the RFC Editor before publication as an RFC ]]
	-08
	o Addressed IESG review comments by Benjamin Kaduk and Roman
	Danyliw, primarily completing the edits to register secp256k1 and
	ES256K as "Recommended: No" for COSE. Some additional security
	considerations were also added.
	-07
	o Addressed editorial SecDir review comment by Linda Dunbar about
	SHA-2 algorithms.
	o Addressed IETF last call comments by Jim Schaad, Rich Salz, and
	Eric Rescorla, now registering secp256k1 and ES256K as
	"Recommended: No" for COSE.
	-06
	o Addressed Area Director review comment by Murray Kucherawy (which
	requested an editorial correction).
	o Changed requested assignment for ES256K from -46 to -47, due to an
	assignment conflict.
	-05
	o Removed unused reference to RFC 7049.
	-04
	o Added explanatory comments on design decisions made that were
	discussed on the mailing list that Jim Schaad requested be added
	to the draft.
	-03
	o Addressed review of -02 by Jim Schaad.
	-02
	o Addressed working group last call comments. Thanks to J.C.
	Jones, Kevin Jacobs, Jim Schaad, Neil Madden, and Benjamin Kaduk
	for their useful feedback.
	-01
	o Changed the JOSE curve identifier from "P-256K" to "secp256k1".
	o Specified that secp256k1 signing is done using the SHA-256 hash
	function.
	-00
	o Created the initial working group draft from draft-jones-cose-
	additional-algorithms-00, changing only the title, date, and
	history entry.
	Author's Address		Author's Address
	Michael B. Jones		Michael B. Jones
	Microsoft		Microsoft
	Email: mbj@microsoft.com		Email: mbj@microsoft.com
	URI: http://self-issued.info/		URI: https://self-issued.info/
End of changes. 53 change blocks.
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