In the same way that tangible bridges connect two physical locations, blockchain bridges connect different networks or token ecosystems. Blockchain bridges are necessary to facilitate communication and movement of assets between one network and another, otherwise, each blockchain would remain in its own siloed island, without outside interaction. 

To understand the concept of bridges and why they are so important, we chat with Consensys’ Layer 2 expert and researcher, Dominik Schmid to get the picture on: 

  1. Why are blockchain bridges important?

  2. Different kinds of bridges

  3. Various security levels - technically and conceptually 

  4. The future of the bridging ecosystem

Why are blockchain bridges important?

We want blockchains to serve billions of users. Ethereum’s initial design simply didn’t scale to meet the widening number of use cases, so our solution is to build many parallel blockchains to take the data and execution load off of the Ethereum Mainnet. With these new Ethereum-compatible parallel blockchains, bridges ease the fragmentation to allow users to hop from one blockchain to another.

What is the difference between “cross-chain” and  “multi-chain” bridges?

Cross-chain bridges connect different blockchains (like Solana to Ethereum) and have greater vulnerability points. We already operate in a multichain ecosystem and it seems likely to be the norm moving forward, however, we need to be careful what kinds of bridges we use and make sure they’re secure enough.

The multi-chain model refers to separate communities building their own technology based on their values. Ethereum and its L2 bridges (Arbitrum, Optimism, zkSync, etc.) vs. Binance Smart Chain’s ecosystem highlights a multi-chain world where the two communities don’t interact and build their own solutions to evolve.

Why is one type of bridge more secure than the other?

The most secure bridges we have right now are rollups. 

Rollups execute transactions in a new environment (i.e. off-chain) and bundle them together, before sending the updated state and transaction data back to Ethereum. They achieve security using proofs—some solutions use mathematical validity proofs applying techniques from zero-knowledge cryptography while others use game theory and staked value to allow for fraud proofs. 

For the non-developer: Rollups aim to dramatically reduce the cost and time of transactions on Ethereum. 

Bridges connecting completely different chains (like Solana to Ethereum, as opposed to Arbitrum to Ethereum Mainnet) can’t be as secure as a rollup. Vitalik’s thesis for why the future will be ‘multi-chain’ but not ‘cross-chain’ lie fundamentally in the limits to the security of bridges that hop across multiple “zones of sovereignty”.

Beware of bridge instabilities

The bridging ecosystem is still fairly nascent. There are always risks with new technologies. Keep the Lindy Effect in mind when evaluating new concepts in the blockchain space, which basically means the longer something has been around, the more likely it is to live longer.

All bridges have different designs and trust assumptions, so make sure to do your due diligence on each bridge before interacting with it. You can do this by checking the documentation and code and observing how mature it is. Are there any red flags that stand out to you?  If so, it’s probably not worth the risk. 

Here are four questions to think about: 

  1. Who operates it?

  2. How’s the data?

  3. What’s the stack like?

  4. How does it prepare for the worst?

Read this piece for further insight on how to judge any Layer 2 solution. 

Bridges are doing amazing work for the space and help foster interoperability and scaling infrastructure. It’s always vital to do your own research before moving assets through a bridge, as some will be better suited to your needs than others.

The future of crypto bridges

Bridges are the future of blockchain connectivity.

"Gateways exist as a way to integrate blockchain networks. These gateways allow for easier movement from one blockchain to another by linking up blockchain networks with some sort of connector, providing the ability to perform atomic swaps without running a full node on each blockchain." - Joel Monegro

As we see this technology being developed and in use more often, we will forget what a pre-bridging blockchain world was like. The convenience and ease that bridges provide will make enormous strides in scaling and innovation. 

Concepts that were purely theoretical will be implemented and battle-tested. And, they will also be susceptible to attacks. 

Always do your own research, and proceed responsibly. 

Happy bridging!