[TLS] [Editorial Errata Reported] RFC8446 (6204)

RFC Errata System <rfc-editor@rfc-editor.org> Thu, 04 June 2020 00:00 UTC

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Subject: [TLS] [Editorial Errata Reported] RFC8446 (6204)
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The following errata report has been submitted for RFC8446,
"The Transport Layer Security (TLS) Protocol Version 1.3".

You may review the report below and at:

Type: Editorial
Reported by: Chris Wood <caw@heapingbits.net>

Section: E.1

Original Text
Implementations MUST NOT combine external PSKs with certificate-based authentication of either the client or the server unless negotiated by some extension.

Corrected Text
Implementations MUST NOT combine external PSKs with certificate-based authentication of either client or the server. Future specifications MAY provide an extension to permit this. 

The existing text can be misread as permitting this combination upon negotiation of the "post_handshake_auth" extension, which would be incorrect. [1] describes an attack that can occur based on this misinterpretation. The proposed text aims to make clear that a *new* extension is required for this combination. 

[1] https://link.springer.com/article/10.1007%2Fs11416-020-00352-0

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RFC8446 (draft-ietf-tls-tls13-28)
Title               : The Transport Layer Security (TLS) Protocol Version 1.3
Publication Date    : August 2018
Author(s)           : E. Rescorla
Category            : PROPOSED STANDARD
Source              : Transport Layer Security
Area                : Security
Stream              : IETF
Verifying Party     : IESG