I used the easy-rsa script to generate some new server certs recently, and found that my strongswan install on OpenWRT could not load the RSA key. This despite the fact that the same key works fine in OpenVPN on the same server. The interesting thing is that when I use the build-key-pkcs12 script instead of the build-key-server script, and then use openssl on the router to extract the cert and key, the key works. it is also a different size. The key kept coming up as 1704 bytes when using the server script, but 1669 bytes with the pkcs12 script. Since the pkcs12 script works, I suggest using it always. It generates the key and crt files any way, even though the extracted key file was a different size than the generated one with the same set of files. There must be a bug somewhere.