HOWTO convert PEM certificates and keys to DER format for emSSL
emSSL requires server certificates and private keys in DER format. Some certificate providers deliver certificates in PEM format which is not immediately compatible with emSSL. You can convert certificates using OpenSSL.
To convert a PEM certificate to a DER certificate
openssl x509 -inform pem -in Certificate.pem -outform der -out Certificate.der
To convert a PEM private key to a DER private key
openssl rsa -inform pem -in PrivateKey.pem -outform der -out PrivateKey.der