fullrt

fullrt - Protocol for full routing table exchange

p3lib-fullrt defines and implements a protocol for peers in P2P networks to request and provide information about their routing table. This mechanism can be used as a building block to construct protocols for privacy preserving lookups in P2P networks such as DHTs. It can also be used as a way for peers to exchange routing information for metrics, security checks [1] and performance optimizations.

p3lib-fullrt as a privacy enhancing mechanism for DHT lookups

p3lib-fullrt has been designed primarily as a mechanism for enhancing privacy on DHT lookups. In many vanilla DHT designs (e.g. Kademlia DHT [2]), the lookup initiator recursively requests other peers for a subset of their routing table containing the peers closest to a certain ID - the resource/peer ID the lookup initiator is interest. This protocol, although effective and highly scalable - leaks information of the lookup initiator's interests to other network peers.

In order to not leak the lookup initiator's interest, she can request the full routing table from other peers and select the subset closest to her interest locally. Note that this approach, although much better from a privacy perspective than vanilla Kademlia - is still vulnerable to passive Range Estimation attacks [1] and active Lookup Bias attacks [1]. These vulnerabilities can be addressed by other primitives and protocols implemented by p3lib.

API

// instantiates a routing table 
rt := kb.NewRoutingTable(10, peerID, time.Duration(time.Second*1), pstore.NewMetrics())

// starts a full routing table provider with a pointer to a routing table
fullRTManager := NewRTProvider(rt)
err, rtBytes := fullRTManager.GetFullRoutingTable()

// rtBytes is an encoded and compressed (optional) snapshot of the current
// routing table which can sent to other network peers

// parse routing table
fullrt := RoutingTableRaw{}
json.Unmarshal(res, &rtBytes)

// for libp2p routing tables, print peer IDs of the routing table
for _, r := range fullrt {
 log.Println(peer.IDB58Decode(r))
}

Check the libp2p example to see how to define the full blown protocol to exchange full routing table information between two network peers.

Examples

Check the example directory to see how to use p3lib-fullrt with libp2p.

FAQ

1. Is using p3lib-fullrt enough to ensure that the lookup initiator's interest not disclosed to other peers?

Not entirely. This approach, although much better from a privacy perspective than vanilla Kademlia - is still vulnerable to passive Range Estimation attacks [1] and active Lookup Bias attacks [1]. These vulnerabilities can be addressed by other primitives and protocols implemented by p3lib. However, it does make it harder for attackers to infer the lookup initiator objectives and it requires more resources (i.e. more colluding peers) to effectively perform the attack.

Keep in mind that p3lib-fullrt is one piece of the puzzle for providing privacy for DHT lookup initiators.

2. Why isn't requesting the full routing table part of the DHT protocol implementations?

Because in most cases, that is not how the lookup protocol is defined. It is much more resource efficient for peers to exchange a subset of entries of the routing table since it requires less data in the wire. But privacy requires most often than not more overhead and resource consumption. Having p3lib-fullrt as an optional mechanism to use allows developers to selectively pick which lookups are important to maintain as private as possible, while leaving other lookups to be more efficient and less private. We aim at building plug and play privacy and giving as much flexibility as possible to dweb app developers and requirements.

3. Peers are exchanging a full routing table over the wire. Isn't this too expensive?

It could be. We are planning to implement compression and sampling in p3lib-fullrt. The goal is to make it optional for peers to request the full routing table or a sample of it (e.g. 40% of its entries, as distributed through the network topology as possible).

References

[1] Octopus: A Secure and Anonymous DHT Lookup

[2] Kademlia DHT