Forwarded with permission. ----- Forwarded message from Caleb James DeLisle <cjd@hyperboria.ca> ----- I'm not really worried about what the IETF has to say, at some point I'll probably add an option to use IPv4 for cjdns too. When you do a DNS lookup for a site it will allocate an address for that machine out of whatever block you choose. Applications won't even have to support IPv6 to support cjdns. As far as address generation speed, the address is a double-sha-512 of your public key so it's extremely fast. Anything less than 128 bits (you're forced to collide the last 8 bits) would be dangerous. I'm sure we could have decided to limit valid keys to a fixed 16 bits or maybe even 24 but 48 bits would be quite unreasonable to expect of small devices. ----- End forwarded message -----