ndncert

We cannot make the assumption that CA will have long term storage. For example, CA may not remember all issued certificates and renewal records.
A possible way is to put extra info into the certificate extension fields.

Besides, we may make use of the certificate extension to do more things. For instance, let CA trust anchor certificate carries ca introduction, and probe instructions? -> a new command tool to generate new cert? or change current key gen to accept mroe info.