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There are still many clients out there that do not support AE ciphersuites (e.g. literally every version of Safari). If SSL Labs capped the grade at B for supp
by agwa 11y ago
There are still many clients out there that do not support AE ciphersuites (e.g. literally every version of Safari). If SSL Labs capped the grade at B for supporting these clients, then the top grade at SSL Labs would effectively become a B, as no serious site would get an A grade anymore. It wouldn't actually accelerate the transition away from these clients/ciphers.
Making the effective top grade a B might also reduce the physiological motivation for improving a seriously bad TLS config. At least in the US, anything less than an A is considered very close to failing these days (it's silly, but it's the reality). Making changes just to get a B isn't nearly as motivational as making changes to get an A.
- tptacek 11y agoThose older clients are actually vulnerable to real cryptographic flaws in TLS.
- agwa 11y agoWhich flaw, specifically, would the latest version of Safari be vulnerable to?
- tptacek 11y agoI guess it depends on your confidence in the Lucky 13 patch, right?
- agwa 11y agoIndeed. And to be clear, I'm not saying we shouldn't be moving away from the CBC ciphers as fast as possible - just that dishing out a B grade for supporting a large number of users is not a good way of accomplishing that.
- Panino 11y agoYou and tptacek are both right, so how about the following to combine your positions: * Grade 'A' requires AES-GCM and ChaCha20Poly1305 * Allow CBC for 'A' iff it's a last resort option * Use nginx equivalent of "ssl_prefer_server_ciphers on;" CBC would then only be used by clients that don't support AE ciphersuites.