Internet DRAFT - draft-jones-webauthn-cose-algorithms
draft-jones-webauthn-cose-algorithms
WebAuthn Working Group M. Jones
Internet-Draft Microsoft
Intended status: Informational May 2, 2018
Expires: November 3, 2018
COSE Algorithms for Web Authentication (WebAuthn)
draft-jones-webauthn-cose-algorithms-01
Abstract
The W3C Web Authentication (WebAuthn) specification uses COSE
algorithm identifiers. This specification registers algorithms in
the IANA "COSE Algorithms" registry that are used by WebAuthn that
are not already registered. Also, they are registered in the IANA
"JSON Web Signature and Encryption Algorithms" registry, when not
already registered there.
Status of This Memo
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This Internet-Draft will expire on November 3, 2018.
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Copyright (c) 2018 IETF Trust and the persons identified as the
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the Trust Legal Provisions and are provided without warranty as
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Notation and Conventions . . . . . . . . . . 2
2. RSASSA-PKCS1-v1_5 Signature Algorithm . . . . . . . . . . . . 2
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
3.1. COSE Algorithms Registrations . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
4.1. RSA Key Size Security Considerations . . . . . . . . . . 4
4.2. RSASSA-PKCS1-v1_5 with SHA-2 Security Considerations . . 4
4.3. RSASSA-PKCS1-v1_5 with SHA-1 Security Considerations . . 4
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. Normative References . . . . . . . . . . . . . . . . . . 4
5.2. Informative References . . . . . . . . . . . . . . . . . 5
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 5
Document History . . . . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
This specification defines how to use several algorithms with COSE
[RFC8152] that are used by the W3C Web Authentication (WebAuthn)
[WebAuthn] specification. These algorithms are registered in the
IANA "COSE Algorithms" registry [IANA.COSE.Algorithms] and also in
the IANA "JSON Web Signature and Encryption Algorithms" registry
[IANA.JOSE.Algorithms], when not already registered there.
1.1. Requirements Notation and Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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 parameterized with a
hash function (h).
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
creating or verifying a signature.
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The RSASSA-PKCS1-v1_5 algorithms specified in this document are in
the following table.
+-------+-------------------------+---------+-----------------------+
| Name | Value | Hash | Description |
+-------+-------------------------+---------+-----------------------+
| RS256 | TBD (requested | SHA-256 | RSASSA-PKCS1-v1_5 w/ |
| | assignment -257) | | SHA-256 |
| RS384 | TBD (requested | SHA-384 | RSASSA-PKCS1-v1_5 w/ |
| | assignment -258) | | SHA-384 |
| RS512 | TBD (requested | SHA-512 | RSASSA-PKCS1-v1_5 w/ |
| | assignment -259) | | SHA-512 |
| RS1 | TBD (requested | SHA-1 | RSASSA-PKCS1-v1_5 w/ |
| | assignment -65535) | | SHA-1 |
+-------+-------------------------+---------+-----------------------+
Table 1: RSASSA-PKCS1-v1_5 Algorithm Values
3. IANA Considerations
3.1. COSE Algorithms Registrations
This section registers the following values in the IANA "COSE
Algorithms" registry [IANA.COSE.Algorithms].
o Name: RS256
o Value: TBD (requested assignment -257)
o Description: RSASSA-PKCS1-v1_5 w/ SHA-256
o Reference: Section 2 of this document
o Recommended: No
o Name: RS384
o Value: TBD (requested assignment -258)
o Description: RSASSA-PKCS1-v1_5 w/ SHA-384
o Reference: Section 2 of this document
o Recommended: No
o Name: RS512
o Value: TBD (requested assignment -259)
o Description: RSASSA-PKCS1-v1_5 w/ SHA-512
o Reference: Section 2 of this document
o Recommended: No
o Name: RS1
o Value: TBD (requested assignment -65535)
o Description: RSASSA-PKCS1-v1_5 w/ SHA-1
o Reference: Section 2 of this document
o Recommended: Deprecated
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4. Security Considerations
4.1. RSA Key Size Security Considerations
The security considerations on key sizes for RSA algorithms from
Section 6.1 of [RFC8230] also apply to the RSA algorithms in this
specification.
4.2. RSASSA-PKCS1-v1_5 with SHA-2 Security Considerations
The security considerations on the use of RSASSA-PKCS1-v1_5 with
SHA-2 hash functions from Section 8.3 of [RFC7518] also apply to
their use in this specification. For that reason, these algorithms
are registered as being "Not Recommended".
4.3. RSASSA-PKCS1-v1_5 with SHA-1 Security Considerations
The security considerations on the use of the SHA-1 hash function
from [RFC6194] apply in this specification. For that reason, the
"RS1" algorithm is registered as "Deprecated". It MUST NOT be used
by COSE implementations.
A COSE algorithm identifier for this algorithm is nonetheless being
registered because deployed TPMs continue to use it, and therefore
WebAuthn implementations need a COSE algorithm identifier for "RS1"
when TPM attestations using this algorithm are being represented.
5. References
5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security
Considerations for the SHA-0 and SHA-1 Message-Digest
Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011,
<https://www.rfc-editor.org/info/rfc6194>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
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[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/info/rfc7518>.
[RFC8017] Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch,
"PKCS #1: RSA Cryptography Specifications Version 2.2",
RFC 8017, DOI 10.17487/RFC8017, November 2016,
<https://www.rfc-editor.org/info/rfc8017>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8230] Jones, M., "Using RSA Algorithms with CBOR Object Signing
and Encryption (COSE) Messages", RFC 8230,
DOI 10.17487/RFC8230, September 2017,
<https://www.rfc-editor.org/info/rfc8230>.
5.2. Informative References
[IANA.COSE.Algorithms]
IANA, "COSE Algorithms",
<https://www.iana.org/assignments/cose/
cose.xhtml#algorithms>.
[IANA.JOSE.Algorithms]
IANA, "JSON Web Signature and Encryption Algorithms",
<https://www.iana.org/assignments/jose/
jose.xhtml#web-signature-encryption-algorithms>.
[WebAuthn]
Balfanz, D., Czeskis, A., Hodges, J., Jones, J., Jones,
M., Kumar, A., Liao, A., Lindemann, R., and E. Lundberg,
"Web Authentication: An API for accessing Public Key
Credentials", Candidate Recommendation, World Wide Web
Consortium (W3C) Recommendation-track, March 2018,
<https://w3c.github.io/webauthn/>.
Acknowledgements
Thanks to John Fontana, Jeff Hodges, Tony Nadalin, Jim Schaad, Goeran
Selander, Wendy Seltzer, Sean Turner, and Samuel Weiler for their
roles in registering these algorithm identifiers.
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Document History
[[ to be removed by the RFC Editor before publication as an RFC ]]
-01
o Updated the requested RS1 value from -262 to -65535 to match the
temporary registration made on 2018-04-19.
o Populated the Acknowledgements section.
-00
o Initial version.
Author's Address
Michael B. Jones
Microsoft
Email: mbj@microsoft.com
URI: http://self-issued.info/
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