No, not the prekeys. I meant the triple DH itself. I think my comment/question might of been confused. It appears that in practice Signal only uses prekeys to

No, not the prekeys. I meant the triple DH itself. I think my comment/question might of been confused. It appears that in practice Signal only uses prekeys to start things off. The prekeys are just signed chunks of the triple DH just stored somewhere for a time. So from that I conclude that Signal does in fact use signatures just like any other public key messaging system. The issue is fundamental after all...