convert PKCS1 private key is PKCS8 (used in java.security.*)
openssl pkcs8 -topk8 -inform PEM -in private.key -outform pem -nocrypt -out pkcs8.pem
create x.509 certificate for private key
openssl req \ -newkey rsa:2048 -nodes -keyout domain.key \ -x509 -days 365 -out domain.crt
Public formats
Private key formats