< draft-ietf-cose-webauthn-algorithms-00.txt   draft-ietf-cose-webauthn-algorithms-01.txt >
COSE Working Group M. Jones COSE Working Group M. Jones
Internet-Draft Microsoft Internet-Draft Microsoft
Intended status: Standards Track March 26, 2019 Intended status: Standards Track July 8, 2019
Expires: September 27, 2019 Expires: January 9, 2020
COSE and JOSE Registrations for WebAuthn Algorithms COSE and JOSE Registrations for WebAuthn Algorithms
draft-ietf-cose-webauthn-algorithms-00 draft-ietf-cose-webauthn-algorithms-01
Abstract Abstract
The W3C Web Authentication (WebAuthn) specification and the FIDO2 The W3C Web Authentication (WebAuthn) specification and the FIDO2
Client to Authenticator Protocol (CTAP) specification use COSE Client to Authenticator Protocol (CTAP) specification use COSE
algorithm identifiers. This specification registers algorithms in algorithm identifiers. This specification registers algorithms in
the IANA "COSE Algorithms" registry that are used by WebAuthn and the IANA "COSE Algorithms" registry that are used by WebAuthn and
CTAP implementations that are not already registered. Also, they are CTAP implementations that are not already registered. Also, they are
registered in the IANA "JSON Web Signature and Encryption Algorithms" registered in the IANA "JSON Web Signature and Encryption Algorithms"
registry, when not already registered there. registry, when not already registered there.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on September 27, 2019. This Internet-Draft will expire on January 9, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 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
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Notation and Conventions . . . . . . . . . . 2 1.1. Requirements Notation and Conventions . . . . . . . . . . 2
2. RSASSA-PKCS1-v1_5 Signature Algorithm . . . . . . . . . . . . 3 2. RSASSA-PKCS1-v1_5 Signature Algorithm . . . . . . . . . . . . 3
3. Using secp256k1 with JOSE and COSE . . . . . . . . . . . . . 3 3. Using secp256k1 with JOSE and COSE . . . . . . . . . . . . . 3
3.1. JOSE and COSE secp256k1 Curve Key Representations . . . . 3 3.1. JOSE and COSE secp256k1 Curve Key Representations . . . . 3
3.2. ECDSA Signature with secp256k1 Curve . . . . . . . . . . 4 3.2. ECDSA Signature with secp256k1 Curve . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
4.1. COSE Algorithms Registrations . . . . . . . . . . . . . . 4 4.1. COSE Algorithms Registrations . . . . . . . . . . . . . . 5
4.2. COSE Elliptic Curves Registrations . . . . . . . . . . . 5 4.2. COSE Elliptic Curves Registrations . . . . . . . . . . . 6
4.3. JOSE Algorithms Registrations . . . . . . . . . . . . . . 5 4.3. JOSE Algorithms Registrations . . . . . . . . . . . . . . 6
4.4. JSON Web Key Elliptic Curves Registrations . . . . . . . 5 4.4. JSON Web Key Elliptic Curves Registrations . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5.1. RSA Key Size Security Considerations . . . . . . . . . . 6 5.1. RSA Key Size Security Considerations . . . . . . . . . . 6
5.2. RSASSA-PKCS1-v1_5 with SHA-2 Security Considerations . . 6 5.2. RSASSA-PKCS1-v1_5 with SHA-2 Security Considerations . . 7
5.3. RSASSA-PKCS1-v1_5 with SHA-1 Security Considerations . . 6 5.3. RSASSA-PKCS1-v1_5 with SHA-1 Security Considerations . . 7
5.4. secp256k1 Security Considerations . . . . . . . . . . . . 6 5.4. secp256k1 Security Considerations . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Normative References . . . . . . . . . . . . . . . . . . 7 6.1. Normative References . . . . . . . . . . . . . . . . . . 7
6.2. Informative References . . . . . . . . . . . . . . . . . 8 6.2. Informative References . . . . . . . . . . . . . . . . . 8
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 9 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 9
Document History . . . . . . . . . . . . . . . . . . . . . . . . 9 Document History . . . . . . . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
This specification defines how to use several algorithms with COSE This specification defines how to use several algorithms with COSE
[RFC8152] that are used by implementations of the W3C Web [RFC8152] that are used by implementations of the W3C Web
Authentication (WebAuthn) [WebAuthn] and FIDO2 Client to Authentication (WebAuthn) [WebAuthn] and FIDO2 Client to
Authenticator Protocol (CTAP) [CTAP] specifications. These Authenticator Protocol (CTAP) [CTAP] specifications. These
algorithms are registered in the IANA "COSE Algorithms" registry algorithms are registered in the IANA "COSE Algorithms" registry
[IANA.COSE.Algorithms] and also in the IANA "JSON Web Signature and [IANA.COSE.Algorithms] and also in the IANA "JSON Web Signature and
Encryption Algorithms" registry [IANA.JOSE.Algorithms], when not Encryption Algorithms" registry [IANA.JOSE.Algorithms], when not
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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 | | Name | Value | Hash | Description |
+-------+-----------------------------+---------+-------------------+ +-------+-----------------------------+---------+-------------------+
| RS256 | TBD (temporary assignment | SHA-256 | RSASSA-PKCS1-v1_5 | | RS256 | TBD (temporary assignment | SHA-256 | RSASSA-PKCS1-v1_5 |
| | -257 already in place) | | w/ SHA-256 | | | -257 already in place) | | using SHA-256 |
| RS384 | TBD (temporary assignment | SHA-384 | RSASSA-PKCS1-v1_5 | | RS384 | TBD (temporary assignment | SHA-384 | RSASSA-PKCS1-v1_5 |
| | -258 already in place) | | w/ SHA-384 | | | -258 already in place) | | using SHA-384 |
| RS512 | TBD (temporary assignment | SHA-512 | RSASSA-PKCS1-v1_5 | | RS512 | TBD (temporary assignment | SHA-512 | RSASSA-PKCS1-v1_5 |
| | -259 already in place) | | w/ SHA-512 | | | -259 already in place) | | using SHA-512 |
| RS1 | TBD (temporary assignment | SHA-1 | RSASSA-PKCS1-v1_5 | | RS1 | TBD (temporary assignment | SHA-1 | RSASSA-PKCS1-v1_5 |
| | -65535 already in place) | | w/ SHA-1 | | | -65535 already in place) | | using SHA-1 |
+-------+-----------------------------+---------+-------------------+ +-------+-----------------------------+---------+-------------------+
Table 1: RSASSA-PKCS1-v1_5 Algorithm Values Table 1: RSASSA-PKCS1-v1_5 Algorithm Values
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 JSON Object Signing and Encryption secp256k1 [SEC2] to be used for JSON Object Signing and Encryption
(JOSE) [RFC7515] and CBOR Object Signing and Encryption (COSE) (JOSE) [RFC7515] and CBOR Object Signing and Encryption (COSE)
[RFC8152] messages. [RFC8152] 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 Standards for Efficient Cryptography Group (SECG) elliptic curve
"secp256k1" [SEC2] is represented in a JSON Web Key (JWK) [RFC7517] secp256k1 [SEC2] is represented in a JSON Web Key (JWK) [RFC7517]
using these values: using these values:
o "kty": "EC" o "kty": "EC"
o "crv": "P-256K" o "crv": "secp256k1"
plus "x" and "y" values to represent the curve point for the key. plus "x" and "y" values to represent the curve point for the key.
Other optional values such as "alg" MAY also be present. Other optional values such as "alg" MAY 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) o "kty" (1): "EC2" (2)
o "crv" (-1): "P-256K" (TBD - requested assignment 8) o "crv" (-1): "secp256k1" (TBD - requested assignment 8)
plus "x" (-2) and "y" (-3) values to represent the curve point for plus "x" (-2) and "y" (-3) values to represent the curve point for
the key. Other optional values such as "alg" (3) MAY also be the key. Other optional values such as "alg" (3) MAY also be
present. present.
3.2. ECDSA Signature with secp256k1 Curve 3.2. ECDSA Signature with secp256k1 Curve
The ECDSA signature algorithm is defined in [DSS]. Implementations The ECDSA signature algorithm is defined in [DSS]. This
need to check that the key type is "EC" for JOSE or "EC2" (2) for specification defines the use of ECDSA with the secp256k1 curve and
COSE when creating or verifying a signature. the SHA-256 [DSS] cryptographic hash function. Implementations need
to check that the key type is "EC" for JOSE or "EC2" (2) for COSE
when creating or verifying a signature.
The ECDSA algorithm specified in this document is: The ECDSA secp256k1 SHA-256 digital signature is generated as
follows:
+--------------+---------------------------+------------------------+ 1. Generate a digital signature of the JWS Signing Input or the COSE
| JOSE Alg | COSE Alg Value | Description | payload using ECDSA secp256k1 SHA-256 with the desired private
| Name | | | key. The output will be the pair (R, S), where R and S are
+--------------+---------------------------+------------------------+ 256-bit unsigned integers.
| ES256K | TBD (requested assignment | ECDSA w/ secp256k1 |
| | -43) | Curve | 2. Turn R and S into octet sequences in big-endian order, with each
+--------------+---------------------------+------------------------+ array being be 32 octets long. The octet sequence
representations MUST NOT be shortened to omit any leading zero
octets contained in the values.
3. Concatenate the two octet sequences in the order R and then S.
(Note that many ECDSA implementations will directly produce this
concatenation as their output.)
4. The resulting 64-octet sequence is the JWS Signature or COSE
signature value.
The ECDSA secp256k1 SHA-256 algorithm specified in this document uses
these identifiers:
+------------+------------------------+-----------------------------+
| JOSE Alg | COSE Alg Value | Description |
| Name | | |
+------------+------------------------+-----------------------------+
| ES256K | TBD (requested | ECDSA using secp256k1 curve |
| | assignment -43) | and SHA-256 |
+------------+------------------------+-----------------------------+
Table 2: ECDSA Algorithm Values Table 2: ECDSA Algorithm Values
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 This section registers the following values in the IANA "COSE
Algorithms" registry [IANA.COSE.Algorithms]. Algorithms" registry [IANA.COSE.Algorithms].
o Name: RS256 o Name: RS256
o Value: TBD (temporary assignment -257 already in place) o Value: TBD (temporary assignment -257 already in place)
o Description: RSASSA-PKCS1-v1_5 w/ SHA-256 o Description: RSASSA-PKCS1-v1_5 using SHA-256
o Reference: Section 2 of this document o Reference: Section 2 of this document
o Recommended: No o Recommended: No
o Name: RS384 o Name: RS384
o Value: TBD (temporary assignment -258 already in place) o Value: TBD (temporary assignment -258 already in place)
o Description: RSASSA-PKCS1-v1_5 w/ SHA-384 o Description: RSASSA-PKCS1-v1_5 using SHA-384
o Reference: Section 2 of this document o Reference: Section 2 of this document
o Recommended: No o Recommended: No
o Name: RS512 o Name: RS512
o Value: TBD (temporary assignment -259 already in place) o Value: TBD (temporary assignment -259 already in place)
o Description: RSASSA-PKCS1-v1_5 w/ SHA-512 o Description: RSASSA-PKCS1-v1_5 using SHA-512
o Reference: Section 2 of this document o Reference: Section 2 of this document
o Recommended: No o Recommended: No
o Name: RS1 o Name: RS1
o Value: TBD (temporary assignment -65535 already in place) o Value: TBD (temporary assignment -65535 already in place)
o Description: RSASSA-PKCS1-v1_5 w/ SHA-1 o Description: RSASSA-PKCS1-v1_5 using SHA-1
o Reference: Section 2 of this document o Reference: Section 2 of this document
o Recommended: Deprecated o Recommended: Deprecated
o Name: ES256K o Name: ES256K
o Value: TBD (requested assignment -43) o Value: TBD (requested assignment -43)
o Description: ECDSA w/ secp256k1 Curve o Description: ECDSA using secp256k1 curve and SHA-256
o Reference: Section 3.2 of this document o Reference: Section 3.2 of this document
o Recommended: Yes o Recommended: Yes
4.2. COSE Elliptic Curves Registrations 4.2. COSE Elliptic Curves Registrations
This section registers the following value in the IANA "COSE Elliptic This section registers the following value in the IANA "COSE Elliptic
Curves" registry [IANA.COSE.Curves]. Curves" registry [IANA.COSE.Curves].
o Name: P-256K o Name: secp256k1
o Value: TBD (requested assignment 8) o Value: TBD (requested assignment 8)
o Key Type: EC2 o Key Type: EC2
o Description: SECG secp256k1 Curve o Description: SECG secp256k1 curve
o Change Controller: IESG o Change Controller: IESG
o Reference: Section 3.1 of [[ this specification ]] o Reference: Section 3.1 of [[ this specification ]]
o Recommended: Yes o Recommended: Yes
4.3. JOSE Algorithms Registrations 4.3. JOSE Algorithms Registrations
This section registers the following value in the IANA "JSON Web This section registers the following value in the IANA "JSON Web
Signature and Encryption Algorithms" registry [IANA.JOSE.Algorithms]. Signature and Encryption Algorithms" registry [IANA.JOSE.Algorithms].
o Algorithm Name: ES256K o Algorithm Name: ES256K
o Algorithm Description: ECDSA w/ secp256k1 Curve o Algorithm Description: ECDSA using secp256k1 curve and SHA-256
o Algorithm Usage Locations: alg o Algorithm Usage Locations: alg
o JOSE Implementation Requirements: Optional o JOSE Implementation Requirements: Optional
o Change Controller: IESG o Change Controller: IESG
o Reference: Section 3.2 of [[ this specification ]] o Reference: Section 3.2 of [[ this specification ]]
o Algorithm Analysis Document(s): [SEC2] o 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 This section registers the following value in the IANA "JSON Web Key
Elliptic Curve" registry [IANA.JOSE.Curves]. Elliptic Curve" registry [IANA.JOSE.Curves].
o Curve Name: P-256K o Curve Name: secp256k1
o Curve Description: SECG secp256k1 Curve o Curve Description: SECG secp256k1 curve
o JOSE Implementation Requirements: Optional o JOSE Implementation Requirements: Optional
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): Section 3.1 of [[ this specification ]] o Specification Document(s): Section 3.1 of [[ this specification ]]
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
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[WebAuthn] [WebAuthn]
Balfanz, D., Czeskis, A., Hodges, J., Jones, J., 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", World Wide Web Consortium
(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 John Fontana, Jeff Hodges, Tony Nadalin, Jim Schaad, Goeran Thanks to Stephen Farrell, John Fontana, Jeff Hodges, John Mattsson,
Selander, Wendy Seltzer, Sean Turner, and Samuel Weiler for their Tony Nadalin, Matt Palmer, Jim Schaad, Goeran Selander, Wendy
roles in registering these algorithm identifiers. Seltzer, Sean Turner, and Samuel Weiler for their roles in
registering these algorithm identifiers.
Document History 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 ]]
-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 -00
o Created the initial working group draft from draft-jones-cose- o Created the initial working group draft from draft-jones-cose-
additional-algorithms-00, changing only the title, date, and additional-algorithms-00, changing only the title, date, and
history entry. history entry.
Author's Address Author's Address
Michael B. Jones Michael B. Jones
Microsoft Microsoft
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