Convert a DER file (.crt .cer .der) to PEM 1openssl x509 -inform der -in certificate.cer -out certificate.pem Convert a PEM file to DER 1openssl x509 -outform der -in certificate.pem -out certificate.der Convert a PKCS#12 file (.pfx .p12) containing a private key and certificates to PEM 1openssl pkcs12 -in …