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proposal: crypto/tls: implement RFC 5929: Channel Bindings for TLS: tls-server-end-point support #65047
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Description
Proposal Details
Dear Golang team, @andres-erbsen (who has added "tls-unique", a part of the RFC 5929),
Can you add the missing "tls-server-end-point" support of RFC 5929: Channel Bindings for TLS?
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
- https://github.com/golang-auth/go-channelbinding
- https://github.com/search?q=repo%3Agolang-auth%2Fgo-channelbinding+tls-unique&type=code
- https://github.com/search?q=repo%3Agolang-auth%2Fgo-channelbinding+tls-server-end-point&type=code
- https://github.com/search?q=repo%3Agolang-auth%2Fgo-channelbinding+tls-exporter&type=code
- https://github.com/go-ldap/ldap
- https://github.com/search?q=repo%3Ago-ldap%2Fldap+tls-server-end-point&type=code
- Add RFC 5929 channel binding support for SSPI client go-ldap/ldap#565
- RFC 9266: Channel Bindings for TLS 1.3: tls-exporter support go-ldap/ldap#392
- https://github.com/golang/go
- https://github.com/search?q=repo%3Agolang%2Fgo+tls-unique&type=code
- fce6388
- proposal: crypto/tls: implement RFC 9266: Channel Bindings for TLS 1.3: tls-exporter support #54103
- proposal: crypto/tls: implement RFC 5929: Channel Bindings for TLS: tls-server-end-point support #65047
- https://github.com/google/conscrypt
- https://github.com/search?q=repo%3Agoogle%2Fconscrypt+tls-unique&type=code
- Add support for accessing tls-unique channel binding value. google/conscrypt#388
- RFC 9266: Channel Bindings for TLS 1.3: tls-exporter support google/conscrypt#1078
- RFC 5929: Channel Bindings for TLS: tls-server-end-point support google/conscrypt#1411
- https://github.com/xmppo/go-xmpp
- https://github.com/search?q=repo%3Axmppo%2Fgo-xmpp+tls-unique&type=code
- https://github.com/search?q=repo%3Axmppo%2Fgo-xmpp+tls-server-end-point&type=code
- https://github.com/search?q=repo%3Axmppo%2Fgo-xmpp+tls-exporter&type=code
- SCRAM: Add support for tls-server-end-point channel binding. xmppo/go-xmpp#177 + Tls-server-end-point improvements. xmppo/go-xmpp#178
cc: @flooey, @andres-erbsen, @jake-scott, @Chrizpy, @mdosch.
Activity
[-]crypto/tls: implement RFC5929 tls-server-end-point support[/-][+]proposal: crypto/tls: implement RFC5929 tls-server-end-point support[/+]ianlancetaylor commentedon Feb 6, 2024
CC @golang/security
Neustradamus commentedon Jun 10, 2025
Dear @golang, @golang/security team,
Have you progressed on it?
Thanks in advance.
Neustradamus commentedon Oct 24, 2025
Dear @golang team, @golang/security team, @seankhliao,
Can you look it?
Important to know:
Thanks in advance.
[-]proposal: crypto/tls: implement RFC5929 tls-server-end-point support[/-][+]proposal: crypto/tls: implement RFC 5929: Channel Bindings for TLS: tls-server-end-point support[/+]samjustus commentedon Mar 2, 2026
we at SUSE Rancher would also appreciate this implementation. Without this, Go applications cannot meet the "Hardened" security requirements enforced by modern Windows Domain Controllers (Active Directory), which increasingly require Channel Binding for LDAP over TLS.
Neustradamus commentedon Jun 17, 2026
@FiloSottile, @seankhliao and all others: Have you seen the recent @samjustus comment?
FiloSottile commentedon Jun 17, 2026
Is this comment incorrect? #54103 (comment)
If not, crypto/tls already supports all the mechanisms being discussed.
FiloSottile commentedon Jun 17, 2026
Based on Section 4 of the RFC, the comment is accurate and there is no need for any new API. Just hash the certificate.
You can file a feature request with whatever LDAP or XMPP library you are using.
JoesSon72 commentedon Jun 17, 2026