RFC 9266: Channel Bindings for TLS 1.3 support

[Neustradamus]

Dear @async-email team,

Can you add the support of RFC 9266: Channel Bindings for TLS 1.3?

• https://datatracker.ietf.org/doc/html/rfc9266

Channel Bindings for TLS: https://datatracker.ietf.org/doc/html/rfc5929

• 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
• tls-server-end-point
• tls-exporter for TLS = 1.3

I think that you have seen the jabber.ru MITM and Channel Binding is the solution:

• 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

Thanks in advance.

Linked to:

• State of Play scram-sasl/info#1
• SCRAM-SHA-1(-PLUS) + SCRAM-SHA-256(-PLUS) + SCRAM-SHA-512(-PLUS) + SCRAM-SHA3-512(-PLUS) supports #99

[link2xt]

Dovecot 2.4.0 added support for channel binding:
https://dovecot.org/mailman3/archives/list/dovecot-news@dovecot.org/thread/UYNR6GBP25XEGFCS633SWPR4HXV3NSS3/

[Neustradamus]

@link2xt: Thanks for your message :)

Yes, It is a very good news to have this new Dovecot 2.4.0 version with TLS Channel Binding support -> SCRAM-SHA-1-PLUS and SCRAM-SHA-256-PLUS in more SCRAM-SHA-1/SCRAM-SHA-256.