I clearly didn't ask my question well enough.

I will probably be wanting to sign it using Crypt::RSA, but what I really need to know is how to retrieve the public and private keys from the certificate file. Although I suppose this is not really a perl question, and is more of a simpleCA question. I will try elsewhere on the net.

I have now read the file further using the decode function of MIME::Base64, and it seems to contain some plaintext and a lot of binary. Now all I need is to understand the format.