I assume that you have a .cer file containing PKCS#7-encoded certificate data and you want to convert it to PEM-encoded certificate data (typically a .crt or .pem file). You can convert PKCS#7 data into PEM format by this command on a file we'll call certfile.cer:
openssl pkcs7 -text -in certfile.cer -print_certs -outform PEM -out certfile.pem
Note that a .cer or .pem file might contain one or more certificates (possibly the entire certificate chain).
Other wise CER
and CRT
extensions mean nothing. Different PKI vendors use different extensions for the same thing.
- Roshith