tox dns3 standard

gistfile1.txt

tox dns3 standard.

Encrypted Tox dns requests and responses.

request:
[4 byte nonce][temporary client public key][encrypted with crypto_box(temporary client public key, server long term public key, 4 byte nonce + 20 byte zeros)[queried username]]

-> base32 (a to z, 0 to 5) -> separate with . as needed.

Notes:
-the temporary public key is a public key temporarily generated that is discarded right after the session is.
-4 byte nonce must be increased by 1 on every request (it must not be generated randomly because birthday problem)
-every 2^32 requests (if that ever happens) the temporary client public key must be changed 
(two requests with the same nonce must never ever happen.)

response:
DNS TXT record:
[encrypted with crypto_box(temporary client public key, server long term public key, 4 byte nonce(sent in request) + 1 byte equal to 1 and 19 bytes of zeros (this is the same 4 byte nonce that was sent in the request))[Tox id (binary format)]]

-> base32 (same as above)

Possible issues with this:
-no PFS (find some way of making the server change its key every couple of days maybe?)
-clients need a local list of tox dns server long term public keys.