Problem: You have generated a CSR using OpenSSL and submitted it to a CA. Your certificate has been issued, but you now want to import it into Windows for use with IIS.
Solution: (run the commands from Linux CLI):
1. Convert the received public key from its PKCS7 format to PEM format:
openssl pkcs7 -outform PEM -in public.p7b -out public.pem -print_certs
2. Combine the public keys and the private key into a password-protected PKCS12 file:
openssl pkcs12 -export -out publicandprivate.pfx -in public.pem -inkey private.key