Author: Hao Tian; Source: Chain View
Recently, the news that Paradigm led a $43 million investment in Succinct ignited the primary market, and the total financing amount of @PolyhedraZK, which just completed TGE, even reached $75 million. It can be seen that the underlying technical facilities of ZKP carry great expectations from the capital market.
In fact, ZK's layer2 expansion has only been tapped to a limited extent. In terms of full-chain interoperability, ZK technology still has a lot of room for imagination. Why? Next, let me talk about my understanding:
In addition to Polyhedra, there are other interoperable communication projects based on ZKP technology, including @SuccinctLabs @RiscZero @ProjectZKM , which are trying to tap the potential of ZK technology and strive for the large-scale adoption of ZK technology.
Most people know about ZK zero-knowledge proof technology only because of its "privacy", "capacity expansion" or "chain abstraction". Few people think about why ZK technology can do this, and whether ZK technology is fully utilized at present.
The reason for this "misunderstanding" is that the real ZK technology has only been used superficially so far, and they are all in the upstream services of star projects such as layer0, zkSync, and Optimism. For example:
Polyhedra provides layerZero with the zkBridge cross-chain asset transfer solution; RISC Zero provides OP-Rollups with the ZK fraud proof system to reduce the time loss of fraud proof; ZKM uses ZK General-Purpose to achieve secure and verifiable computing, ultimately enabling Ethereum to become the global settlement layer.
In short: these ZK underlying technology projects are exploring the large-scale application of ZK zero-knowledge proof technology from different angles, and working hard to overcome several key challenges:
1. Develop general-purpose zero-knowledge proof technology;
2. Build a distributed proof system;
3. Optimize the computing consumption in the ZK proof process;
4. Provide a development environment compatible with multiple programming languages;
5. Expand the hardware support range of zero-knowledge proof computing, including PC, mobile terminals, IOT devices, etc.
Compared to the upstream technical services of projects such as RISC Zero, Succinct, and ZKM, the interoperable "cross-chain bridge" problem that @Polyhedra wants to solve is closer to the current market landing. Let's take the more familiar zkBridge as an example to show where the hard-core confidence of ZKP technology lies?
Polyhedra built a distributed ZK proof system deVirgo. Virgo is an open source that helps developers build and verify non-interactive zero-knowledge proof protocols. Nodes do not need to do "trusted initialization" and can directly become Provers without permission. deVirgo is a high-efficiency distributed ZKP protocol based on the Virgo protocol that can support multiple distributed computing networks and shorten the proof generation time.
The first zk-SNARK protocol implemented based on the deVirgo distributed proof system is zkBridge, which aims to achieve information communication, cross-chain assets and data sharing in a cross-chain environment. At present, cross-chain communication services of more than 25 chains have been realized. The well-known layer0 uses the zkBridge service provided by Polyhedra, while layerZero focuses more on infrastructure construction services such as chains and DApps in a full-chain environment.
Why is zkBridge so important? Because it can directly use the capabilities of the POS public chain nodes themselves to achieve communication interaction at the "consensus layer".
Generally speaking, if we want to achieve interactive operation between chains A and B, the common way is to build a "chain in the chain", which has its own consensus mechanism and distributed verification nodes to ensure the asset security of cross-chain interaction. In order to improve service capabilities, the relay chain will deploy interactive smart contracts on each chain that supports smart contracts, and the total smart contract of the relay chain will regulate the assets of smart contracts distributed on each chain.
For example, when a user initiates an asset transfer from chain A to chain B, the relay chain will first let the smart contract on chain A lock a certain asset, and then let the smart contract on chain B release a certain asset. During the whole process, the relay chain must monitor all the records of on-chain operations to ensure the correct locking and release of assets between different chains. Only in this way can the relay chain control the total balance of assets and manage the ledger to avoid double spending.
However, the relay chain itself will allocate an extra layer of trust cost. Only when users trust the relay chain and the relay chain must build smart contracts with the same interaction standards in each isomorphic chain environment, if it encounters a non-smart contract chain such as BTC, it must develop and adapt to ensure the safe circulation of assets.
In short, the cross-chain services provided by the relay chain will eventually test the Security Committee behind the total smart contract management, and the committee is composed of a group with an identity or an MPC multi-signature management subject, which becomes a "distrust factor".
As the most common cross-chain solution, most layer2s use security committee governance to ensure asset security. Once the committee group intends to do evil, the losses caused are irreversible.
The power of zkBridge lies in that it can give full play to the potential of zk zero-knowledge proof technology, allowing the nodes maintaining the consensus layer between the two chains to directly establish communication and securely control the transfer of assets. The deVirgo distributed system that provides interoperability is not a specific relay chain, but more like an open source, permissionless and trusted third-party component.
The nodes of chain A can generate zk-SNARKs states through deVirgo to initiate asset transfer statements, and the nodes of chain B can directly verify the correctness of the ZKP proof through deVirgo, and it can also consume very low computing and time costs.
Obviously, technical service solutions such as zkBridge are more likely to gain market trust than the relay chain service of the MPC multi-signature security committee, and are actually more secure and efficient. (Note: This is only a relative concept. At present, many cross-chain solutions are still MPC multi-signature, and the ZK infrastructure needs to be further strengthened)
zkBridge can directly allow all nodes of the Pos chain to participate in the entire proof generation and verification process, but it is not conducive to rapid and horizontal expansion. What should we do? Polyhedra solves this problem through the zkLightClient light client.
1. The use of light clients can reduce resource requirements and consume less storage, bandwidth and computing resources;
2. The use of light clients can be horizontally compatible with non-smart contract chains or other heterogeneous chains, providing a wider range of interoperability. For example, the BTC chain can only use light clients and hash time locks to control asset transfers;
3. The use of light clients plus layerZero's lightweight integrated assistance can simplify the threshold for developers, shorten the development cycle, and accelerate the popularization of the entire chain infrastructure.
Since the calculation, verification and communication process of zero-knowledge proofs requires a series of processing operations, there are too many technical difficulties to overcome in order to weigh the cost, consumption and timeliness. To some extent, it is reasonable for the "chain-in-chain" cross-chain solution to become a market choice.
However, looking to the future, ZK cross-chain solutions, including Polyhedra, Succinct, ZKM, RISC Zero, etc., are being improved and optimized in the direction of light weight, high efficiency, and low energy consumption.
In more detail, for example, Polyhedra proposed Single Slot Finality using deVirgo and improved signature schemes. BLS is a digital signature scheme that allows multiple signatures to be combined into one to reduce storage and data transmission. By combining BLS signatures with ZKP, compact proofs can be created to prove that some necessary signatures have been completed without the need to transmit and verify the signatures themselves, thereby reducing latency and making each Slot block final after it is generated.
In addition, as the demand for BTC layer2 to use BTC as the main chain asset settlement layer increases, Polyhedra has specially set up the Bitcoin AVS node system by borrowing Eigenlayer's dual-staking economic system, giving Bitcoin trust-minimized interoperability. At the same time, by using the dual-mapping liquidity pool on BTC and ETH and the role-collaboration locking asset of Maker, and applying the special FRI encoding method, ZK proof can be directly verified on Bitcoin, completing the most difficult part of ZK full-chain interoperability.
ZK aims not only to be the Endgame of layer2, but also to become the Endgame of the full-chain infrastructure.
The above
As a representative of the implementation of ZKP technology, polyhedra is accelerating the implementation of various ZKP solutions. Only a part of them are listed above, just to let everyone clearly feel the advantages of ZKP as the underlying technical framework.
In fact, the potential of the entire ZKP track is far more than what Polyhedra provides. More upstream suppliers of ZK technology infrastructure are accelerating the large-scale popularization of ZKP technology in vertical subdivisions such as ZK cross-chain bridge, ZK lightweight, ZK General-Purpose, ZK Coprocessor, and ZK distributed Prover system.
It is no exaggeration to say that the maturity of each ZK subdivision will have a reshaping effect on the current industry. The ZK technology applications we see now are only the tip of the iceberg.
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