Maxwell, co-author of Wuille, proposal to significantly increase Bitcoin's bandwidth

A proposed new relay protocol could reduce the "transaction bandwidth" used by Bitcoin nodes by up to 75%.

Called Erlay, the proposed protocol alters the way transactions are relayed so that they use much less bandwidth, an important resource for the nodes making up the network. The authors include Gleb Naumenko, a researcher at the University of British Columbia, as well as two heavyweights in bitcoin development: Greg Maxwell and Pieter Wuille.

The way bitcoin works is that nodes around the world bind together to form a network. Under the hood, once a transaction is broadcast, it impacts on this vast network of hardware.

Erlay changes the way in which the announcement of these transactions is made. As Naumenko has described in an email from dev Bitcoin announcing the new proposal:

"The main idea is that instead of announcing each transaction to each peer, ads are only sent directly to a small number of connections (only 8 outgoing). An additional relay is obtained by periodically executing a set reconciliation protocol on each connection between the two-way masked ad units. "

The results, according to Naumenko: "We save half the bandwidth consumed by a node, we allow increasing connectivity almost for free and, therefore, better resistance to timing attacks. If the number of outgoing peers has increased to 32, Erlay saves about 75% of its overall bandwidth compared to the current protocol. "

The researchers argue that one of the important results of this new protocol is that by reducing the bandwidth required by this process, the nodes can increase the number of connections that they maintain with each other. other nodes.

Eclipse Attack

As low and technical as it may seem, this is an important research, especially with regard to the security of the network itself.

Bitcoin security depends at least in part on connections between nodes. This new protocol could make room for more connections. The more a node is connected, the more it is "hardened" against network attacks.

Naumenko described one of these attacks at CoinDesk: "The most trivial example is the Eclipse attack, when a target node is isolated from the longest chain because all its connections are made with an attacker. In this case, an attacker, for example, can make a target node believe that it has paid for this target node (display a shorter string with that string). [transaction] in), without actually submitting transactions to the longer chain ".

The impact of this attack on Bitcoin is described in more detail in a 2015 research paper.

So, if the protocol is so important for the security of Bitcoin, what is the next step? Will it be added to Bitcoin Core, the most widespread software implementation of Bitcoin?

"A few weeks ago, I spoke with several contributors to Bitcoin Core and the feedback was generally positive, although they asked for more experiences. Now that these experiences are being added, I will give everyone more time to become familiar with the new technical elements, "Naumenko told CoinDesk.

In general, new technologies are not added to Bitcoin unless the most active contributors to the software, as well as the larger ecosystem that actually exploits the nodes (and, unlike minors, do not receive any kind of built-in subsidy or compensation), agrees with it.

"We have received positive signals from the community, which encourages us to continue working on implementation," he added. If the community continues to enjoy it, then: "The protocol should be part of one of the major future releases (hopefully, of the next)."

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