openssl證書轉換

openssl x509 -inform der -in certnew.cer -out cer_mail.pem #導出證書，不包含私鑰
openssl pkcs12 -in cer2p7b.pfx -nocerts -nodes -out cer_mail_private.key #導出私鑰
cat cer_mail.pem cer_mail_private.key >cert_mail.pem #合成包含私鑰的pem證書