Simple deifnition of zkSync
  • zkSync is a user-centric zk rollup platform from Matter Labs. It is a scaling solution for Ethereum, already live on Ethereum mainnet.
    • It supports payments, token swaps and NFT minting.

Some of the main features of zkSync are:

  • Extremely low transaction fees
  • Trustless protocol
  • Funds are cryptographically secure, as in the Ethereum mainnet
  • Users are always in control of their funds
  • No requirement for operational activity to keep the funds safe
Overview of zkSync
  • zkSync is a zkRollup by Matter Labs that is built for scalable payments, where users can deposit onto the network and transfer between other zkSync accounts at a fraction of the costs on Ethereum.
  • zkEVM is a virtual machine that executes smart contracts in a way that is compatible with zero-knowledge-proof computation. It is the key to building an EVM-compatible ZK Rollup while preserving the battle-tested code and knowledge gained after years of working with Solidity. Our zk-EVM keeps EVM semantics, but is also ZK-friendly and takes on traditional CPU architectures.
  • The launch of the zkEVM represents an essential turning point for crypto. Up until recently it was still considered merely a theoretical possibility that will take years to get real. But over the last year, the pace of the entire zero knowledge proof ecosystem has exceeded even experts’ expectations. And because of the many R&D breakthroughs (opens new window)by our team, that made zk-EVM possible, Solidity programmers now have first-class access to the unmatched scaling, security, and UX benefits of zero knowledge proofs.
What is zkSync 2.0?

zkSync 2.0 is an EVM-compatible ZK Rollup being built by Matter Labs, powered by our zkEVM.

But this is not our first product! zkSync 1.0 has been live for payments (opens new window)for almost 1.5 years:

  • zkPorter (opens new window)puts data availability — essential transaction data needed to reconstruct state — offchain rather than on Ethereum. Instead, data availability is secured using proof of stake (PoS) by zkSync token stakers. This enables much higher scalability (tens of thousands TPS), and as a result, ultra-low transaction fees comparable with sidechains (in the range of a few cents).
  • The security of zkPorter is still better than any other L1 or sidechain. In the worst case, where a malicious actor controls both the sequencer and over ⅔ of the total stake, they can sign a valid state transition but withhold the data. In this case, the state is “frozen” and users will not be able to withdraw, but the attacker’s stake is frozen as well. Thus, there is no direct way for an attacker with a large stake to financially benefit from an exploit.
  • For an in-depth dive into the scale and security of zkPorter, check out this Medium post.
Comparing zkSync with other options
  • Ethereum sidechains, as well as some separate L1 blockchains, have their own security mechanisms and a bridge with Ethereum. Sometimes the bridge validators are identical with the sidechain validators and use the same staking mechanism (e.g. in case of Polygon/Matic PoS).
  • The most important thing to understand about this topic is that no matter how the sidechain itself is secured, when it’s used as a scaling solution, security of the assets always depends on the goodwill of the majority of the bridge validators. If the majority is compromised, they can irreversibly steal all of the assets.
    • And since most bridges operate in a delegated PoS model under a low latency consensus requirement, the majority of the stake is usually controlled by only a handful of validator servers physically located in the same data center. The risk of all of these servers being compromised is nontrivial and a lot more than a theoretical threat!
  • zkSync 2.0 offers two account types to its users: zkRollup and zkPorter. Let’s consider the comparison for each of them:
1) zkRollup vs Sidechains
  • zkRollups provide the same level of security as L1 itself, but at lower costs (roughly 1/50th of the costs on L1). Sidechains, on the other hand, depend on the honest majority assumptions to achieve much lower fees.
2) zkPorter vs Sidechains
  • zkPorter (opens new window)offers sidechain-like ultra-low fees, but with an order of magnitude more security.
  • zkPorter relies on Ethereum for transaction validity and on zkSync token stakers for data availability.
  • In the worst case, where a malicious actor controls both the sequencer and over ⅔ of the total stake, they can sign a valid state transition but withhold the data. This would freeze the state and users would not be able to withdraw, but the attacker’s stake is frozen as well.
  • This is still a much stronger guarantee than sidechains, because no hack can be directly exploited and there is no economic benefit from being compromised. Moreover, guardian nodes can run on consumer hardware, so they don’t require delegated PoS. This means much higher decentralization, which leads to much higher digital security: a hacker might need to break hundreds if not thousands of guardian nodes to control the majority of the stake.
Bottom line
  • No matter what zkSync account type you choose, it’s going to be a lot more secure than sidechains. zkRollups accounts will offer the highest security, while zkPorter accounts will offer comparable costs. In any case, all users will be able to seamlessly interact with each other, making for a much larger liquidity pool.
Roadmap on zkSync
  • The first phase of zkSync’s roadmap started with the deployment of zkSync - a zkRollup focused on scalable payments.
  • Phase 2 plans for composable smart contracts on a new network called zkSync 2, which is expected to release on mainnet sometime in the next few months. Alongside it, a new programming language, Zinc, will be natively supported, as will Solidity.
  • zkSync 2 will also introduce zkPorter, a PoS chain that will allow zkSync 2 users to publish transaction data on zkPorter instead of Ethereum, enabling higher transaction throughput. Because zkPorter transactions aren’t limited by Ethereum transaction fees, it is expected to be an even cheaper alternative.
  • Phase 3 introduces privacy, unlocking the other notable feature of zkRollups. This will be done at a time when zk proofs won’t add significant overhead to the system. The final phase involves transitioning zkSync 2 towards censorship resistance - requiring the system to decentralize and become permissionless by removing any complete control the Matter Labs team has over the network.