p12 -> pem
cer.p12: openssl pkcs12 -clcerts -nokeys -out cer.pem -in cer.p12
key.p12: openssl pkcs12 -nocerts -out key.pem -in key.p12
合：cat cer.pem key.pem > cer_key.pem
pem -> p12
openssl pkcs12 -export -in apns_dev.pem -out paypal.p12
