Re: [TLS] security considerations for draft-rescorla-tls-subcerts

[Simon Friedberger <[e-mail]>]

It seems the intention behind short lived certificates is pretty clear:

   Server operators
   often want to create short-lived certificates for servers in low-
   trust zones such as CDNs or remote data centers.


But even if this is true it needs to be analyzed why server operators want
to do this and if their reasons are good ones.


The only example of a security gain I can think of is the following:
If a breach remains undetected but is accidentally fixed for example
through automatic updates. In this case a revocation will not be issued
but short-lived certificates would still invalidate the certificates an
attacker may have stolen.

I suppose, this is similar to the common notion of rotating secrets.


To me the increase in security weighted with the difficulty of obtaining
such short-lived certificates from a CA probably does not justify the extra
complexity of adding subcerts.


Best,
Simon