Browsers switching to DANE would be a major step backwards in transparency, which has in fact led to bad CAs being distrusted (WoSign, Symantec, Certionomis, Camerfirma, ...). Yeah, MTA-STS sucks but this is way off-topic from the blog post.
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DANE isn't a step backwards for transparency. Enforcing TLSA records does not require dropping WebPKI + CT as requirements for certificates to be considered valid. DANE can be used for pinning rather than fully replacing WebPKI. It's not a choice between security or transparency.
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I'm saying that Chrome should be enforcing DNSSEC + DANE when using DoT/DoH. I'm not saying that they replace the existing requirements with a different approach but that they should support pinning via DNSSEC + DANE to allow sites to stop trusting CAs for users with DoT/DoH.
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Many DANE advocates do want it to be available as a full replacement for WebPKI. I'm not suggesting that Chrome should do that. It's usable as either a full replacement or a pinning mechanism. I know Chrome isn't going to drop CT and I'm not proposing that it should be doing it.
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Got it, glad you clarified that.
It doesn't seem as strong as HPKP though, because you're still reliant on trusted third parties with DANE. HPKP let you avoid TTPs entirely, or at least choose the ones you wanted to trust.
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HPKP doesn't work for the first connection or when the pins have expired. DNSSEC + DANE secures the first connection. It relies on DNS as a root of trust, just like WebPKI does for DV. You can choose which TLD operator you want to trust though, instead of trusting all of them.
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True, though you have to trust the DNS root regardless. Also, switching TLDs would really suck if yours turns out to be untrustworthy.
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Many CAs are clearly untrustworthy but are still trusted by browsers because it's too hard to remove them. A website can't choose not to trust CAs for WebPKI. They have to trust all of them. The alternative is not providing things via a website. At least you CAN switch TLDs.
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I think it's crucial to keep in mind that the DNS root and TLD operators are already 100% capable of obtaining valid WebPKI certificates for the websites using them. DANE is not replacing trusting all CAs with trusting TLD + root DNS but rather just removing trusting all CAs.
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Consider it a site that uses .ly (Libya) as their TLD. The TLD operator can already take over their DNS and obtain a certificate from a CA like Let's Encrypt. This will appear in CT logs, but it is not misissuance on the part of Let's Encrypt. It helps detect it, and then what?
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I don't think DANE + DNSSEC introduces any new new trust in DNS, and my suggestion is that it should only be used as an additional check when present rather than an alternative, so any value provided by WebPKI is still preserved. If sites don't like DANE they can just not use it.
DANE is particularly suitable for protocols like SMTP, which unavoidably already trust DNS, because MX records set the name to be checked in the server certificate. MTA-STS jumps through very ugly hoops (and still remains vulnerable on first contact) to try to work around this.
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As for the DANE "constraint" modes (certificate usages PKIX-TA(0) and PKIX-EE(1)), yes they could be used to harden WebPKI. The major browsers are not keen on tackling the last mile problem (home routers and ISPs serve crippled DNS), which is a barrier to non-datacentre DANE.
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