[tptacek]

No, "full DNSSEC", in the hypothetical universe in which browsers ever supported DANE, simply moves you from having to trust CA's like LetsEncrypt to having to trust the registrars and the world governments that have (often de jure) control over domain registration. DNSSEC does not eliminate centralized external trust anchors; it depends utterly on them.

† (spoiler: Apple, Google, and Mozilla dabbled with it and then rescinded their support; Mozilla and Google have both stated, Google more formally than Mozilla, that DANE isn't happening)

[magila]

As long as DV certs exist the registrars are trusted anyways[0]. DNSSEC + DANE, for all its faults, would at least reduce the set of trusted actors by cutting CAs out of the chain.

[0] Yes there's CT to help catch dishonest registrars, but a similar regime could be applied to registrars directly to force transparency around changes to TLSA records.

[tptacek]

Adam Langley explains in "Why Not DANE In Browsers" that this is not in fact the case, and that DANE will ultimately just expand the number of trust anchors; you can't even get things narrowed down to just the governments controlling your records.

Further: a mis-issuing CA can be put to death (as happened to the largest CA when Google caught them mis-issuing). You can't revoke a TLD.

Meanwhile, CT actually exists today and is meaningfully combating misissuance, and obviously does not rely on DNSSEC to function.

[Ajedi32]

> Adam Langley explains in "Why Not DANE In Browsers" that this is not in fact the case, and that DANE will ultimately just expand the number of trust anchors

This is false. That article makes no such claims.

[tptacek]

There are two ways that you might wish to use DANE in a web browser: either to block a certificate that would normally be considered valid, or to bless a certificate that would normally be rejected. The first, obviously, requires that DANE information always be obtained—if a lookup failure was ignored, a network attacker with a bad certificate would just simulate a lookup failure. But requiring that browsers always obtain DANE information (or a proof of absence) is nearly implausible

[Ajedi32]

That paragraph does not claim DANE expands the number of trust anchors.

As magila stated, registrars are already a trust anchor for domain validated certificates. Trusting a certificate directly via DANE vs through a domain-validated certificate doesn't change that. It does, however, cut CAs out of the process, which reduces the number of trust anchors.

[tptacek]

If you can't use DANE to block certificates that the WebPKI says are valid, then you're stuck trusting both DANE and the CAs. Browsers don't trust DANE today. Ergo, adoption of DANE would expand the number of trust anchors.

[magila]

I was speaking more in a hypothetical sense, but you're right. The DNS as currently implemented is sufficiently broken so as to preclude securing it.