Using openssl to generate private Key

[Jason A. Donenfeld]

This seems to work, maybe:

openssl genpkey -algorithm X25519 -outform der | tail -c 32 | base64

openssl genpkey -algorithm X25519 -outform der | tail -c 32 | base64 | wg pubkey

I haven't verified what's happening in the code though, so use at your
own risk. wg(8) is the best way to generate wireguard private keys for
use with wireguard.