> CT has a bit of an implicit dependency on heterogeneous configurations - that at least some clients report violations, and that attackers cannot easily distinguish reporting clients from non-reporting clients.
Unless I'm misunderstanding you, this isn't really how CT works: the expectation for clients under a PKI with CT is that the presented certificate is already present in one or more logs, meaning that it's never (or more accurately, never has to be) the client actually doing the reporting. Reporting is left to separate monitoring parties.
In other words: a global adversary cannot surreptitiously use a novel CA against a particular configuration; they must first make themselves visible to one or more CT logs. Failing to do so means that their CA will be rejected outright by the client (or accepted by the client if the client doesn't do CT, but still with a loss of stealth).
Unless I'm misunderstanding you, this isn't really how CT works: the expectation for clients under a PKI with CT is that the presented certificate is already present in one or more logs, meaning that it's never (or more accurately, never has to be) the client actually doing the reporting. Reporting is left to separate monitoring parties.
In other words: a global adversary cannot surreptitiously use a novel CA against a particular configuration; they must first make themselves visible to one or more CT logs. Failing to do so means that their CA will be rejected outright by the client (or accepted by the client if the client doesn't do CT, but still with a loss of stealth).