How to convert .cer and .key file to .pem?

Question

I have a .cer certificate, .key file and I would like to convert it to the .pem format.

How do I convert them to .pem?

Answer 1

Assuming you have the .key PK,
and .cer/.crt/.cert file in the correct format
(i think common-name is mandatory)

// in Linux

cat x.key x.cert > x.pem

// in Windows

copy /b x.key+x.cert x.pem

Answer 2

I used openssl to do the conversion and it works.

Convert 'certificate.cer' to 'certificate.pem'

openssl x509 -inform DER -in certificate.cer -out certificate.pem

Convert 'yourkeyfile.key' to 'yourkey.pem'

openssl rsa -in yourkeyfile.key -out yourkeyfile.pem

Bundle both certificate.pem and yourkey.pem as a single cert+key.pem

cat certificate.pem yourkey.pem > cert+key.pem