Re: [briar-devel] Gnunet

[Michael R. <mi...@br...>]

On 15/09/17 18:12, Darien Alonso wrote:
> What do you think about implementing something like the bitcoin
> network. If someone wants to participate in the Briar network can
> choose to be a "full node" or "a client". Full nodes participate in a
> p2p network and clients can connect to it. This way if A sends a
> message to B, message from A lives inside the network until B connects
> to and the message is downloaded to B's device and it's deleted from
> the network.

This idea certainly reduces the bandwidth load on clients, but it
doesn't solve the problem that anyone can flood the network, and it
leaks metadata to the network about which messages clients send and receive.

> With this approach only "full nodes" needs to sync and users does not
> have to meet in person to add contacts because I can not see how could
> be useful having to meet in person to add contacs, share some
> information, send a message or have access to a blog post.

The reason for meeting in person is to make sure you've exchanged keys
with the right person and not an attacker. We're working on ways to add
contacts remotely, but they'll never offer the same level of assurance
as meeting in person.

> A city or
> even a whole country could be interconnected through wifi access
> points running as full nodes. I thing the "flood" problem could be
> addressed guessing how many information can generate a real person in
> comparison with an autonomous system.

Unfortunately rate-limiting wouldn't solve the flooding problem. Imagine
the attacker runs a full node. The other nodes don't know if there are
thousands of clients connected to that node or if the attacker's
generating all the messages herself. If you put a rate limit on each
node then the attacker can just run a lot of nodes.

The fundamental problem is that the resources used by the network to
broadcast a message to all nodes grow with the number of nodes, whereas
the resources used by the sender are constant. So given a fixed attack
budget, the attacker can impose a scaling limit on the network.

Cheers,
Michael