Comment by tptacek
18 hours ago
No? DANE is a dead letter. It doesn't work reliably on all Internet paths; too many middleboxes flip out if they see a DNS packet that doesn't look like every other DNS packet. For many years, there was an effort to work around that with "DANE stapling", where the signed DANE records were tacked on to the TLS handshake. But that leaves a chicken/egg problem, because attackers can strip the DANE records out of the handshake. The project was abandoned several years ago, and with it any real prospect of DANE becoming mainstream.
I think that's for the best; there are much bigger problems with DANE/DNSSEC than TLS reliability.
I don't think (and wouldn't hope) this would be a flag-day thing where we stop using CA trust completely all at once and only use DANE afterward. DANE would become an option, disabled or secondary by default, that users could choose to use as a fallback if CA-based TLS validation fails. Eventually as adoption increased and the critical paths got cleaned up, DANE could become the default primary, with a fallback to CA trust if there's no valid response to a TLSA record request. Eventually as CA trust fell completely out of favor for most uses, it wouldn't be necessary for many clients to support it at all.
See, this doesn't work either. One of the core jobs you have designing a secure transport is avoiding downgrade attacks, and the construction you just outlined is not only downgradable, it's explicitly downgradable, as a feature. That's not going to happen.
So the answer is just to use only the weaker option forever?
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