[tptacek]

We have short lifetimes because TLS revocation doesn't work. It's that simple.

To understand the distinction, imagine a password system where you can't change your password. You can make new ones, but the old ones still work. That's the problem TLS was facing.

[nickf]

Not quite that simple, no. It's a good reason, and while CRL and OCSP don't really work well - CRLite/OneCRL, CRLsets and valid all go some way to making revocation reasonably effective. Having an effective way to rotate all certificates, quickly, is a bigger reason. 1k -> 2k RSA took too long. SHA1 -> SHA2 took waaaaay too long. Changing anything about the webPKI takes too long unless everyone is on short lifetimes. The post-quantum bogeyman looms, too. Heartbleed and unforced CA errors become way less of a problem is everyone is forced to rotate monthly.

[tptacek]

Fair enough (I knew someone was going to come in here and whack me on this). I'd only say that this makes the overall argument for short-lifetime certs even stronger. :)

[nickf]

…and I didn’t even have to play the SC-081 sponsor card either ;)

[ocdtrekkie]

Even granting that, it's still both an ineffective fix and it introduces significantly worse security risks than it tries to mitigate, on a system that at its core is fundamentally bad.

PKI is structurally broken at every level. The reason there are so many changes and additions and new features being slapped on it, is because it's a really dumb system and the people who control it are very motivated to keep it in place at the expense of everything else.

[tptacek]

No, it doesn't.