X509转PFX：
openssl pkcs12 -export -inkey test.key -in test.cer -out test.pfx
PFX转X509：
openssl pkcs12 -in test.pfx -nodes -out test.pem
openssl rsa -in test..pem -out test.key
openssl x509 -in test..pem -out test.crt
原文：https://www.cnblogs.com/xiaoleiel/p/11160817.html