RFC 5929: Channel Bindings for TLS: tls-server-end-point support

[Neustradamus]

Suggested enhancement

Dear @Mbed-TLS team, @davidhorstmann-arm, @gilles-peskine-arm, @tom-cosgrove-arm, @waleed-elmelegy-arm, @gowthamsk-arm and @mfil (who has added "tls-exporter", RFC 9266),

Can you add the missing "tls-server-end-point" support of RFC 5929: Channel Bindings for TLS?

• https://datatracker.ietf.org/doc/html/rfc5929
• https://www.rfc-editor.org/rfc/rfc5929#section-4

Recently, @simo5 explains why it is needed here: https://mailarchive.ietf.org/arch/msg/kitten/-hhno2IUJQwXOyJT3-CTaKxoOuA/

• XEP-0388: Extensible SASL Profile: https://xmpp.org/extensions/xep-0388.html
• XEP-0440: SASL Channel-Binding Type Capability: https://xmpp.org/extensions/xep-0440.html
• XEP-0474: SASL SCRAM Downgrade Protection: https://xmpp.org/extensions/xep-0474.html
• XEP-0480: SASL Upgrade Tasks: https://xmpp.org/extensions/xep-0480.html

Little details, to know easily:

• tls-unique for TLS =< 1.2 (RFC5929)
• tls-server-end-point =< 1.2 + 1.3 (RFC5929)
• tls-exporter for TLS = 1.3 (RFC9266)

After the jabber.ru MITM, it is time to add it:

• https://notes.valdikss.org.ru/jabber.ru-mitm/
• https://snikket.org/blog/on-the-jabber-ru-mitm/
• https://www.devever.net/~hl/xmpp-incident
• https://blog.jmp.chat/b/certwatch/certwatch

Thanks in advance.

Linked to:

• Channel Binding: State of Play scram-sasl/info#1
• RFC 9266: Channel Bindings for TLS 1.3 support #6150
• Implement TLS-Exporter #9421
• [Backport 3.6] Implement TLS-Exporter #9469 (3.6 backport)
• Equivalent to SSL_get_peer_finished #10134

Justification

Mbed TLS needs this because it is supported by several companies, projects/softwares and it does not work with Mbed TLS.