gnupg: Dirmngr CACHECERT
3.6.5 Put a certificate into the internal cache
-----------------------------------------------
Put a certificate into the internal cache. This command might be useful
if a client knows in advance certificates required for a test and wants
to make sure they get added to the internal cache. It is also helpful
for debugging. To get the actual certificate, this command immediately
inquires it using
S: INQUIRE TARGETCERT
C: D <DER encoded certificate>
C: END
Thus the caller is expected to return the certificate for the request
as a binary blob.
The return code is 0 for success; i.e. the certificate has not been
successfully cached or one of the usual error codes from libgpg-error.