There are several TLS modes that don't use certificates. SRP and PSK are the two that I have some limited experience with. Both require sharing a password or

There are several TLS modes that don't use certificates. SRP and PSK are the two that I have some limited experience with. Both require sharing a password or key beforehand through some other medium. If you're not concerned with man-in-the-middle attacks, then you could also use the ANON modes.