Some encoders, like those provided by the dnskey and sshkey plugins,
require these separately when encoding keys.
Also fixes the type for the ASN.1 encoding (which is a subjectPublicKeyInfo
structure) depending on the key type. This worked fine for PEM encoding
as the pem plugin doesn't care what the actual type of the key is (which
is encoded in the SPKI structure), but other plugins do (e.g. the sshkey
plugin).
Tobias Brunner
4e73e9d3e9