Thanks for the detailed response, that is very much appreciated. When I wrote the initial email, I had more in mind some sort of configuration - as opposed to DANE. I agree that the use of PSKI should not cause any of the headaches associated with pinning.
Yours, Daniel On Mon, Jun 13, 2022 at 11:56 AM Viktor Dukhovni <ietf-d...@dukhovni.org> wrote: > On Mon, Jun 13, 2022 at 10:42:51AM -0400, Daniel Migault wrote: > > > I sent this question regarding the use of SPKI Fingerprints to the > > add mailing list, but I am also eventually interested to feed backs not > > necessarily restricted to encrypted resolvers. > > > > RFC 7858 (DNS over TLS) indicates the use of SPKI Fingerprints in an > > analogous manner to that described in RFC7469 (public KEy Pinning > extension > > for HTTP). I am wondering if anyone is aware of implementation > considering > > SPKI Fingerprints for or if such usage is not something we would like to > > recommend/deprecate. > > SPKI fingerprints are used in DANE, specifically either: > > * DANE-EE(3) SPKI(1) SHA2-256(1)/SHA2-512(2) records > * PKIX-EE(1) SPKI(1) SHA2-256(1)/SHA2-512(2) records > > Since the TLSA records are published by the service operator, questions > about stale data largely go away, modulo a small fraction of negligent > operators (in SMTP stale TLSA records are seen for ~1% of MX hosts, but > more importantly, only 0.0053% of DANE-enabled domains). > > Also, OpenSSL supports use of SPKI fingerprints for peer certificate > verification, because "TLSA record" lookups are left up to the > application, which feeds these into the SSL handle prior to the > handshake. This makes it possible to synthesise TLSA "[31] 1 [12]" > records corresponding to an SPKI fingerprint, and use these in > peer certificatre chain verification. > > Postfix, for example, has a "fingerprint" TLS "security level", in which > the peer is authentication via a locally specified SPKI fingerprint, and > this actually implemented on top of the OpenSSL DANE API via the above > mentioned synthetic TLSA records. > > -- > VIktor. > > _______________________________________________ > TLS mailing list > TLS@ietf.org > https://www.ietf.org/mailman/listinfo/tls > -- Daniel Migault Ericsson
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