Speakers: Soumya Basu
Transcript By: Bryan Bishop
bloXroute: A network for tomorrow’s blockchain
Hi. I am Souyma and I am here to talk with you about Bloxroute. The elephant in the room is that blockchains have been claimed to solve everything like credit cards, social media, and global micropayments. To handle credit card payment volumes, blockchains need like 5000 transactions per second, for microtransactions you need 70000 transactions per second, and for social media even more. Blockchains today do about 10 transactions/second.
One solution is to increase capacity. What if you try increasing the block size in bitcoin and seeing how far it can take you? This works up to a point. If we look at bitcoin, and this was just before segwit, bitcoin had less than a 1% orphan rate at about 3 transactions/second. Ethereum during the same time period had a 6% orphan rate and about 13 transactions/second. So we really need to look at why this is happening and why can’t we just increase capacity.
This boils down to how information propagates in the p2p network. So how this works is that when a miner mines a block, they first sending to their neighbors. Then it propagates to neighbors on the network. Also, say that during the hops there’s a node that doesn’t have a lot of bandwidth. They download more slowly, they validate more slowly. If some user is at the other end of the hops, the throughput is limited by the intermediate nodes bandwidth. Your latency while if you look at just the beefy nodes and pumping you up you will get improvements in latency because it will be this slow node that dominates eventually.
((If you can’t validate all the data, then the adversary can hide invalid data in your mega blocks.))
High-throughput systems exist
We know how to build high-throughput systems. They exist. Netflix can stream gigabytes of data with no problem. Their solution is to trust a central authority. But this doesn’t work for blockchain. We want to decentralize control to many, many entities. Let’s take a step back and ask what do we want from our network layer?
We want the best of both worlds: we want the security of a peer-to-peer network which is completely oblivious where it’s hard to censor information based on where it comes from and what its content is. But we also want the scalability of a centralized network, where we want thousands of transactions per second and we want blocks to propagate at low latency, like hundreds of milliseconds across the whole world.
Bloxroute lets each network perform at its own strength. Blockstrap keeps the p2p network but only for the security properties. On top of the p2p network, Bloxroute has a bunch of servers that are very powerful. The network on top of it is optimized for high-throughput and low latency. What happens is the p2p network will audit this network if it can ever download all of the data. The p2p network doesn’t do that much work, most of the work is offloaded to the Bloxroute network and then we can get this nice sweetspot of having the performance of a centralized solution but the control is still in the p2p network.
In terms of performance, Bloxroute does one thing: it broadcasts data very quickly. The goal is to provide abstraction to an end node of being directly connected to every other peer in the p2p network. Under the hood, unbenknowst to the blockchain p2p network, the p2p network is being used to check for content and censorship of blocks based on content or censorship of blocks based on origin. There should be no censorship based on content or origin. The exact p2p network structure should not be revealed to anyone.
Some of the links should only be known to the two parties involved in links in the p2p network. That’s the only way to do it.
Cut through routing
Consider two nodes connected by a Bloxroute gateway. This is a timing diagram on the screen. Time will go downwards. We’re looking at a block being sent. This is how the transmission looks. The idea is that at some point, the source node will start transmitting blocks the first byte of the block will be transmitted to the gateway and that delay here is the latency between those two nodes. The Bloxroute server before receiving the whole block will immediately start transmitting the first byte before it’s done transmitting the whole block. The destination will get the block much more quickly.
If you zoom out on this diagram, the difference between having the Bloxroute server in between the two nodes and not, is this very very small switching latency. So essentially each Bloxroute server acts like a router in between the source and destination nodes so it’s essentially a man-in-the-middle.
First we provide obliviousness to content. So we do this by sending encrypted blocks through the network. You encrypt a block before you send it, using symmetric key encryptions. Then you listen to your neighbors. Not all of the neighbors are public, so it’s hard for Bloxroute network to know or do an eclipse attack and only send it to your neighbors because Bloxroute doesn’t really know who your neighbors are. Once you receive enough confirmations, you can then broadcast the key.
If Bloxroute decides after decrypting your block that it doesn’t like the content of your block, sure it could censor the data, but the key is very small. So it’s fast to propagate a small key to decrypt the censored block. The p2p network is at the worst case transmitting a small key to keep Bloxroute in check.
Second we need obliviousness to source. So you should always relay a block indirectly through one of your peers. This obfuscates the origin and makes it hard for Bloxroute to know who is the original person that sent this block.
Preventing critical failures
We make test blocks of dummy data. The purpose of these test blocks is just to make sure that Bloxroute is behaving correctly. If Bloxroute decides to engage in some misbehavior, then it’s more likely to happen on a test block than a real block. These blocks are removed by the gateways so the Bloxroute node doesn’t actually see this happening behind the scenes.
The security checks that we outlined previously restrict Bloxroute to two behaviors: it either serves the network in a neutral manner, or it just stops serving the network at all. So to prevent this from causing damage, we have a bunch of backup networks. If Bloxroute stops serving a particular network, then these networks can take over Bloxroute’s functionality. The way we do this is by open-sourcing the Bloxroute server so that anyone can run the server side of the Bloxroute network for free without resource costs. This is a temporary solution until someone comes up with a solution to replace the Bloxroute network.
Each peer to peer node will run an additional Bloxroute gateway process. The gateway provides two abstractions simultaneously: the first one is to the actual blockchain node. If you think about in bitcoin, you have the bitcoin node and the Bloxroute gateway on the same machine. So it looks like a peer on the network and the gateway is also connected to the Bloxroute service and thinking the Bloxroute protocol. It performs all the security checks and everything I just covered. So this is incrementally deployable, and any gateways connected to us will get the increased performance and will have these security checks being done so ideally it will incentivize people to actually go on our network.
I think the coolest part about this is that the gateways are agnostic to server implementations. I didn’t make any assumptions about how exactly people will make the software for my project. Sure we can do cut-through routing, but the security checks don’t depend on that. The server side performance can be optimized fairly independently of the gateway security guarantees they need to provide.
Other consensus protocols
I’ve been talking mainly about bitcoin and Nakamoto consensus. Bloxroute provides strong security guarantees on the network itself. The reason it needs to do that is that Nakamoto consensus makes strong network assumptions for safety. In the bitcoin network, if you partition the network so that the two halves of the network can talk to each other quickly but any blocks traveling between them would take forever, then eventually these two partitions would have a forked blockchain. It requires the network to behave well, for safety.
This strong safety guarantee is not true for every consensus protocol. For example, one of the most popular permissioned protocols, PBFT, assumes a fully asynchronous network. The nice thing about Bloxroute is that some of the security techniques that we have while necessary for consensus protocols that have strong network requirements may actually be removable for other consensus protocols. This is really dependent on exactly how the protocol is structured and what it looks like.
Bloxroute is a re-think of the network layer from first principles. We provide strong neutrality guarantees, and the reason is that we want to make this applicable to all consensus protocols. There’s a lot to look forward to. We’re benchmarking this and deploying this on some of the most popular blockchains including Bitcoin, Bitcoin Cash and Ethereum. I’m happy to take any questions.
Q: Are the servers incentivized in any way? Are they altruistic?
A: There’s a whole token model behind this to correctly incentivize Bloxroute to keep providing this service. There’s an ICO.
gleb: What if ISP start to censor traffic going to Bloxroute nodes?
A: If ISPs start to censor or delay Bloxroute nodes… this is the same with any other p2p network. ISPs can start identifying what looks like bitcoin traffic.
gleb: But your nodes are very expensive. Bitcoin’s defense is that nodes are cheap.
A: You can look into encryption or move IP addresses. There’s different techniques that would help with this.