convert openssl key pair to PKCS #12 format
This command will convert a standard openssl key / cert pair into PKCS #12 format for use with Windows’ certmgr:
# openssl pkcs12 -export -in ssl.crt -inkey ssl.key -out ssl.p12
A password must be supplied during conversion as Windows’ certmgr will ask for a credential. It simply won’t accept an empty credential.
While importing in certmgr choose PKCS #12 format (.pfx or .p12 file extensions).