Re: [TLS] [Technical Errata Reported] RFC5246 (6572)

Eric Rescorla <ekr@rtfm.com> Wed, 05 May 2021 23:01 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Wed, 5 May 2021 16:00:00 -0700
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To: RFC Errata System <rfc-editor@rfc-editor.org>
Cc: Tim Dierks <tim@dierks.org>, Roman Danyliw <rdd@cert.org>, Benjamin Kaduk <kaduk@mit.edu>, Christopher Wood <caw@heapingbits.net>, Joseph Salowey <joe@salowey.net>, sean+ietf@sn3rd.com, johannes.goerlich@siemens.com, "<tls@ietf.org>" <tls@ietf.org>
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Subject: Re: [TLS] [Technical Errata Reported] RFC5246 (6572)
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I'm not sure precisely what attacks you are referring to here. In
particular, I'm not aware of any known security issues with HMAC-SHA1. With
that said, I agree that we wouldn't choose AES_128_CBC_SHA as a default
now, but this isn't usually the kind of thing we would usually use an
erratum for. Rather, this would be appropriate for a new RFC updating 5246.

-Ekr


On Wed, May 5, 2021 at 3:21 AM RFC Errata System <rfc-editor@rfc-editor.org>
wrote:

> The following errata report has been submitted for RFC5246,
> "The Transport Layer Security (TLS) Protocol Version 1.2".
>
> --------------------------------------
> You may review the report below and at:
> https://www.rfc-editor.org/errata/eid6572
>
> --------------------------------------
> Type: Technical
> Reported by: Johannes Görlich <johannes.goerlich@siemens.com>
>
> Section: 9
>
> Original Text
> -------------
> In the absence of an application profile standard specifying otherwise, a
> TLS-compliant application MUST implement the cipher suite
> TLS_RSA_WITH_AES_128_CBC_SHA (see Appendix A.5 for the definition).
>
> Corrected Text
> --------------
> In the absence of an application profile standard specifying otherwise, a
> TLS-compliant application MUST implement the cipher suite
> TLS_RSA_WITH_AES_128_GCM_SHA256 (see Appendix A.5 for the definition).
>
> Notes
> -----
> A must-be-implement cipher suite should not relay on a bulk encryption
> algorithm which is vulnerable to plain-text attacks or on a secure hash
> algorithm which has been proven to be insecure.
>
> Instructions:
> -------------
> This erratum is currently posted as "Reported". If necessary, please
> use "Reply All" to discuss whether it should be verified or
> rejected. When a decision is reached, the verifying party
> can log in to change the status and edit the report, if necessary.
>
> --------------------------------------
> RFC5246 (draft-ietf-tls-rfc4346-bis-10)
> --------------------------------------
> Title               : The Transport Layer Security (TLS) Protocol Version
> 1.2
> Publication Date    : August 2008
> Author(s)           : T. Dierks, E. Rescorla
> Category            : PROPOSED STANDARD
> Source              : Transport Layer Security
> Area                : Security
> Stream              : IETF
> Verifying Party     : IESG
>