* Over head is quite small, at just 225 bytes if assuming 5 hops
* Most likely also don’t even need the message at all?
* What would it contain?
* Bunch of TODO’s still left in the code, need to write the portion for
processing and forwarding mix headers received by the nodes.
* After the processing stuff, need to write an extensive set of tests
to ensure correctness.
* Also, need to figure out the division between nodeID and lightning
address. For sphinx, they must be “prefix free”.
* Meaning the way we calculate the shared secret
* They get M = (G * x_us) * b_0, they calc the secret with M * x_them
* M * x_them = G * x_us * b_ * x_them
* We have H = (G * x_them), we calc with H * (x_us * b_0 mod n))
* H * (x_us * b_0) = G * x_them * x_us * b_0
