Why aren't DHT public key records signed?

From @JustinDrake on Tue Jan 17 2017 15:46:06 GMT+0000 (UTC)

IPFS clients publish their public key on the DHT. Those records are not signed. Why not?

My guess: the validity of the public key can be checked by hashing it and comparing it to the peer ID. No signature required.

Copied from original issue: https://github.com/ipfs/faq/issues/220

From @Kubuxu on Mon Jan 23 2017 18:25:15 GMT+0000 (UTC)

Yes the identity directly corresponds to the public key, it is better signature then RSA could ever give. Other DHT records (provider) are not currently signed due to size and computation costs of RSA. We are planning switch to x25519 crypto which will enable us to sign those records fast and cheaply