If your CA has sent you the certificate file in a format that your server doesn’t accept, you’ll need to convert the certificate file’s format. You can easily do this on your own system by running a few OpenSSL commands. Down below, we have compiled OpenSSL commands that you’ll need based on your certificate format and server type.

Convert PEM file to other Formats

OpenSSL commands to convert PEM file to other Formats

Convert PEM to DER
openssl x509 -outform der -in certificate.pem -out certificate.der

Convert PEM to P7B
openssl crl2pkcs7 -nocrl -certfile certificate.cer -out certificate.p7b -certfile CACert.cer

Convert PEM to PFX
openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt -certfile CACert.crt

OpenSSL commands to convert DER file
Convert DER to PEM
openssl x509 -inform der -in certificate.cer -out certificate.pem

OpenSSL commands to convert P7B file
Convert P7B to PEM
openssl pkcs7 -print_certs -in certificate.p7b -out certificate.cer

Convert P7B to PFX
openssl pkcs7 -print_certs -in certificate.p7b -out certificate.cer

openssl pkcs12 -export -in certificate.cer -inkey privateKey.key -out certificate.pfx -certfile CACert.cer
OpenSSL commands to convert PFX file

Convert PFX to PEM
openssl pkcs12 -in certificate.pfx -out certificate.cer -nodes