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: https://www.rfc-editor.org/errata/eid6205 -------------------------------------- Type: Editorial Reported by: Martin Thomson <m...@lowentropy.net> Section: 4.3.2 Original Text ------------- Servers which are authenticating with a PSK MUST NOT send the CertificateRequest message in the main handshake, though they MAY send it in post-handshake authentication (see Section 4.6.2) provided that the client has sent the "post_handshake_auth" extension (see Section 4.2.6). Corrected Text -------------- Servers which are authenticating with a resumption PSK MUST NOT send the CertificateRequest message in the main handshake, though they MAY send it in post-handshake authentication (see Section 4.6.2) provided that the client has sent the "post_handshake_auth" extension (see Section 4.2.6). Servers which are authenticating with an external PSK MUST NOT send the CertificateRequest message either in the main handshake or request post-handshake authentication. Future specifications MAY provide an extension to permit this. Notes ----- The lack of qualification on "authenticating with a PSK" implies that the statement applies equally to both external and resumption PSKs. However, there are two conditions being governed: whether a certificate can be requested during the handshake, and whether a certificate can be requested post-handshake. The latter of these requires different rules depending on the type of PSK. We know from the analysis of resumption (see https://mailarchive.ietf.org/arch/msg/tls/TugB5ddJu3nYg7chcyeIyUqWSbA/) that combining a PSK handshake of either type with a client certificate is not safe. Thus, the prohibition on CertificateRequest during the handshake applies equally to both resumption and external PSKs. For post-handshake, Appendix E.1 already discusses the risks of combining PSKs with certificates, citing the same analysis as above. [...] It is unsafe to use certificate-based client authentication when the client might potentially share the same PSK/key-id pair with two different endpoints. For this reason an external PSK is not safe to use with post-handshake authentication. A resumption PSK does not have this property, so the same prohibition doesn't apply. Splitting the requirements as proposed makes this split clearer. 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. -------------------------------------- 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 _______________________________________________ TLS mailing list TLS@ietf.org https://www.ietf.org/mailman/listinfo/tls
