Mutating and transforming certificates and keys Using OpenSSL
These commands allow you to convert certificates and keys to different formats to make them compatible with specific types of servers or software. For example, you can convert a normal PEM file that would work with Apache to a PFX (PKCS#12) file and use it with Tomcat or IIS. Use our SSL Converter to convert certificates without messing with OpenSSL.
Convert a DER file (.crt .cer .der) to PEM
openssl x509 -inform der -in certificate.cer -out certificate.pem
Convert a PEM file to DER
openssl x509 -outform der -in certificate.pem -out certificate.der
Convert a PKCS#12 file (.pfx .p12) containing a private key and certificates to PEM