% gpgsm --import test.crt
% gpgsm --export-private-key-p12 -out foo.p12 (no passphrase)
% openssl pkcs12 -in ns.p12 -clcerts -nodes > key+cert.pem
% gpgsm --import test.crt
% gpgsm --export-private-key-p12 -out foo.p12 (no passphrase)
% openssl pkcs12 -in ns.p12 -clcerts -nodes > key+cert.pem