Internet-Draft JOSE: Deprecate 'none' and 'RSA1_5' March 2024
Madden Expires 19 September 2024 [Page]
Javascript Object Signing and Encryption
7518 (if approved)
Intended Status:
Standards Track
N. Madden
Illuminated Security Ltd

JOSE: Deprecate 'none' and 'RSA1_5'


This draft updates [RFC7518] to deprecate the JWS algorithm "none" and the JWE algorithm "RSA1_5".

About This Document

This note is to be removed before publishing as an RFC.

The latest revision of this draft can be found at Status information for this document may be found at

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This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on 19 September 2024.

Table of Contents

1. Introduction

JSON Web Algorithms (JWA, [RFC7518]) introduced several standard algorithms for both JSON Web Signature (JWS) and JSON Web Encryption (JWE). Many of these algorithms have stood the test of time and are still in widespread use. However, some algorithms have proved to be difficult to implement correctly leading to exploitable vulnerabilities. This draft deprecates two such algorithms:

1.1. The 'none' algorithm

The "none" algorithm creates an Unsecured JWS, whose contents are completely unsecured as the name implies. Despite strong guidance in the original RFC around not accepting Unsecured JWS by default, many implementations have had serious bugs due to accepting this algorithm. In some cases, this has led to a complete loss of security as authenticity and integrity checking can be disabled by an adversary simply by changing the algorithm ("alg") header in the JWS. The website [howmanydays] tracks public vulnerabilities due to implementations mistakenly accepting the "none" algorithm. It currently lists 12 reports, many of which have high impact ratings.

Although there are some legitimate use-cases for Unsecured JWS, these are relatively few in number and can easily be satisfied by simply base64url-encoding some JSON instead. The small risk of breaking some of these use-cases is far outweighed by the improvement in security for the majority of JWS users who may be impacted by accidental acceptance of the "none" algorithm.

1.2. The 'RSA1_5' algorithm

The "RSA1_5" algorithm implements RSA encryption using PKCS#1 version 1.5 padding [RFC8017]. This padding mode has long been known to have security issues, since at least Bleichenbacher's attack in 1998. It was supported in JWE due to the wide deployment of this algorithm, especially in legacy hardware. However, more secure replacements such as OAEP [RFC8017] or elliptic curve encryption algorithms are now widely available. NIST has disallowed the use of this encryption mode for federal use since the end of 2023 [NIST.SP800-131r2] and a CFRG draft [I-D.kario-rsa-guidance] also deprecates this encryption mode for IETF protocols. This document therefore also deprecates this algorithm for JWE.

1.3. Guidance on deprecation

Both of the algorithms listed above are deprecated for use in JWS and JWE. JOSE library developers SHOULD deprecate support for these algorithms and commit to a timeline for removal. Application developers SHOULD disable support for these algorithms by default. New specifications building on top of JOSE MUST NOT allow the use of either algorithm.

2. Conventions and Definitions

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.

3. Security Considerations

No security issues are introduced by this specification.

4. IANA Considerations

The following changes are to be made to the IANA JOSE Web Signature and Encryption Algorithms registry:

5. References

5.1. Normative References

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, DOI 10.17487/RFC7518, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.

5.2. Informative References

Sanderson, J., "How Many Days Has It Been Since a JWT alg:none Vulnerability?", , <>.
Kario, H., "Implementation Guidance for the PKCS #1 RSA Cryptography Specification", Work in Progress, Internet-Draft, draft-kario-rsa-guidance-02, , <>.
Barker, E. and A. Roginsky, "NIST SP 800-131A Rev. 2: Transitioning the Use of Cryptographic Algorithms and Key Lengths", , <>.
Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch, "PKCS #1: RSA Cryptography Specifications Version 2.2", RFC 8017, DOI 10.17487/RFC8017, , <>.


Author's Address

Neil Madden
Illuminated Security Ltd