Some fetcher plugins (such as curl) might build upon OpenSSL to implement
HTTPS fetching. As we set (and can't unset) threading callbacks in our
openssl plugin, we must ensure that OpenSSL functions don't get called after
openssl plugin unloading.
We achieve that by loading curl and all other fetcher plugins after the base
crypto plugins, including openssl.
To avoid considering each cached OCSP response and evaluating its trustchain,
we limit the certificates considered for OCSP signing to:
- The issuing CA of the checked certificate
- A directly delegated signer by the same CA, having the OCSP signer constraint
- Any locally installed (trusted) certificate having the OCSP signer constraint
The first two options cover the requirements from RFC 6960 2.6. For
compatibility with non-conforming CAs, we allow the third option as exception,
but require the installation of such certificates locally.
Andreas Steffen