[saag] Re: Errata 6576 - HOTP
Simon Josefsson <simon@josefsson.org> Fri, 07 March 2025 18:16 UTC
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From: Simon Josefsson <simon@josefsson.org>
To: Michael StJohns <msj@nthpermutation.com>
In-Reply-To: <ad9a04e7-36e4-4c6e-ab96-d80ad4691ddc@nthpermutation.com> (Michael StJohns's message of "Fri, 7 Mar 2025 12:53:07 -0500")
References: <ad9a04e7-36e4-4c6e-ab96-d80ad4691ddc@nthpermutation.com>
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Date: Fri, 07 Mar 2025 19:15:47 +0100
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Subject: [saag] Re: Errata 6576 - HOTP
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Michael StJohns <msj@nthpermutation.com> writes: > https://www.rfc-editor.org/errata/eid6756 > > > RFC 4226 <https://www.rfc-editor.org/rfc/rfc4226>, "HOTP: An > HMAC-Based One-Time Password Algorithm", December 2005 > > Another problem with the same document. > > Recommend: Accept. > > The reference implementations cited match this described behavior and > specifying the last byte of the HMAC makes more sense than always the > 20th byte (correct for HMACSHA1 only). While that is a change needed to implement RFC 6238 (HOTP SHA2), I don't think that is a proper fix RFC 4226 which is SHA1-only. If anything needs to be clarified, I think it should be an errata to RFC 6238 to explain that section 5.3 of RFC 4226 has to modified in this way in order to implement SHA2. A new bis document could be prepared that merged RFC 4226 and RFC 6238 including clarifications. /Simon
- [saag] Errata 6576 - HOTP Michael StJohns
- [saag] Re: Errata 6576 - HOTP Simon Josefsson