4. General weirdness A. They do an out of band transfer of address, which is the encoded hashes of the ECC public key(s?), instead of doing out of band transfer of the encoded ECC public keys themselves. The addresses are used to query the network for the public keys. Requesting public keys in this way is probably an attack vector, if an attacker can tell who requested the public key then they can obviously link the communicating parties together. Since there needs to be an out of band information exchange in order to get the hash of the public key, why not just use an out of band exchange of the public key and have the address of the party BE their public key instead of the hash of it? That makes a hell of a lot more sense, and base58 (wtf) encoded SHA512 hashes of ECDH public keys are going to be of comparable size to encoded ECDH public keys themselves. B. I don't think they actually need to use a different ECC key for ECDSA and ECDH if they go about it correctly. It is funny that they do for ECC but didn't for RSA where they definitely should have.