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> So the number of users affected would be small in either case. And if there's a root CA out there granting invalid certificates, there's enough interest in ke
by schoen 9y ago
> So the number of users affected would be small in either case. And if there's a root CA out there granting invalid certificates, there's enough interest in keeping the trusted roots clean that it would get patched up pretty quickly anyway.
However, HPKP is one of the mechanisms today that can best detect this activity happening. (In the future, CT with mandatory log inclusion proofs should be better.) People don't just learn about misissuance events by magic, but by having technologies that provide other channels for checking what certificates exist in the wild or what certificates UAs should expect.
Also, some misissuance can be unintentional on the CA's part, so pinning can conceivably also help clean up the CA's practices.
You might be right that these factors weight against HPKP most of the time, but for the core misissuance-detection one, the situation is a bit more complicated because of the way that HPKP itself helps with catching these situations.
- syrrim 9y agoThere is a header one can set, as an alternative to HPKP, that will merely notify you in the event of a misissuance, rather than block off your domain. Perhaps that would be preferable?
- schoen 9y agoYes, the notification mode would probably often be sufficient in many cases (and I think might be what caught the DigiNotar compromise?). I forgot what happens if an attacker tries to block the notification from going through, though.