Converting SSL Certificates
From Jonsdocswiki
It is possible to generate an SSL certificate key and certificate signing request with open SSL (see this article) and then get an SSL certificate from a Certificate Authority. Unfortunately, the Microsoft family of Operating Systems (and products like IIS and ISA) won't accept an OpenSSL generated .key so adding your .cert or .crt to these applications is useless.
Alas, all is not lost - you just have to convert your .key and certificate into a PKCS bundle. Fortunately, you can use OpenSSL to do that too.
