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CAA support wasn't mandatory for WebPKI CAs until 2017-09-08 so it's likely that it's better supported now than it was last year.
by an_account_name 8y ago
CAA support wasn't mandatory for WebPKI CAs until 2017-09-08 so it's likely that it's better supported now than it was last year.
- peterwwillis 8y agoAssuming every CA's support was perfect (again, 650 of them, so not likely), CAA still does not stop these attacks. Domains have to implement CAA. Most domains do not, so most domains remain vulnerable. Even if the domain does, if either they or a CA screw anything up, they are vulnerable. The client will accept any cert signed by any CA. One rogue cert screws the security. Compare this to if the client was verifying it using a blockchain. The blockchain provides a record that the client can verify, not only from multiple peers that share the same records, but at the sources of the original records, to verify a CA was authorized, and to verify a specific domain owner created a cert. This is a much higher barrier to attack than what CAA provides. Even if this verification were optional, it would be a much better authenticity guarantee than what clients get today. The other thing a blockchain would provide is protection against state actors. If the FBI barges into Verisign waving a FISA warrant, they could possibly force Verisign to generate valid certs outside of the CT or CAA process. A blockchain could show the client that a cert it received was never in the blockchain. Comparing the blockchain to CT could further emphasize rogue certs.