Interpretation of Opside White Paper V2

What is Opside

Opside is a decentralized ZK-RaaS (ZK-Rollup as a Service) platform and a PoW network that supports ZKP (Zero-Knowledge Proof) mining. Opside adopts PoS & PoW hybrid consensus, providing Web3 developers with the function of generating zkEVM application chain with one click. At the same time, the ZKP computing tasks brought by a large number of ZK-Rollups also generate a huge demand for computing power, thus providing a meaningful mining scenario for global miners.

In the field of capacity expansion, the concept of L2 is no stranger. However, L2 cannot coordinate various types of hardware resources well, such as data availability, ZKP computing power, packaging nodes, etc. In addition, operating a L2, especially ZK-Rollup, requires high hardware maintenance costs and professional technical thresholds, so many developers are discouraged. In response to these problems, Opside proposed the concept of ZK-RaaS for the first time. Developers can start a zkEVM chain of their own within one minute without mastering the knowledge of ZK or chain nodes. At the same time, Opside also proposed the concept of ZK-PoW, introducing the role of miners to participate in the maintenance of zkEVM nodes and the calculation of ZKP.

The purpose of Opside is to make ZK-Rollup more friendly and popular, thus making it possible to implement large-scale application chains based on zkEVM.

• ZK-Rollup as a Service: For developers, one-click deployment of their own ZK-Rollup (zkEVM) on multiple chains
• Opside ZK-PoW Cloud: For miners, Opside is also a multi-chain PoW protocol that supports ZK mining and generates zero-knowledge proofs for ZK-Rollup on multiple public chains.

ZK-RaaS

ZK-RaaS (ZK-Rollup as a Service) can provide anyone with the service of generating ZK-Rollup with one click.

Opside provides a general ZK-Rollups launchbase, through which developers can easily deploy different types of ZK-Rollups to different base chains.

• base chain, including Ethereum/Opside chain/BNB chain/Polygon PoS and other public chains.
• ZK-Rollup type, including zkEVMs such as zkSync, Polygon zkEVM, Scroll, StarkNet, and other types of ZK-Rollups.

On each base chain, Opside will deploy a Rollup system contract (Rollup Contracts, RSC) to manage the life cycle of the Rollup on the chain, including operations such as registration, suspension, and exit. Developers can own a ZK-Rollup by spending a certain amount of IDE (Opside token) to lease a Rollup slot.

The concept of Rollup slot is similar to Polkadot slot or Cosmos application chain, but the Cosmos application chain needs to maintain a set of consensus layer and cross-chain bridge, which brings great security risks. ZK-Rollup adopts ZK technology, which strictly guarantees that Rollup and base chain share the same consensus and data availability layer in a mathematical sense, which is more secure, more decentralized, and lower maintenance costs.

After the developer rents a Rollup slot, he has an independent operating environment. For example, the developer can own a zkEVM chain independently. Developers have sovereignty over ZK-Rollup and can customize the rollup economic model, including choosing gas tokens. Developers can freely adjust the gas fee, even 0, so that users do not need to pay any fees.

Developers do not need to bear any hardware costs. All hardware resources, including data availability, sequencer, ZKP computing power, etc., are provided decentralized by the following Opside ZK-PoW cloud.

In addition, native cross-rollup communication can be realized between ZK-Rollups on the same base chain. Cross-rollup communication is a message communication mechanism. That is to say, an address on one rollup can directly call a contract on another rollup. This greatly solves the problem of fragmentation of user assets and enhances the composability between applications.

Opside ZK-PoW Cloud

Compared with OP-Rollup, ZK-Rollup has many advantages, including safer, trustless and faster withdrawal speed. At the same time, there is also a very big difference in technology, that is, ZK-Rollup additionally requires a powerful ZKP computing power to support the generation of zero-knowledge proofs.

Multi-chain ZK-PoW mechanism

Opside ZK-PoW Cloud will be deployed on multiple chains, including but not limited to Ethereum, BNB Chain, Polygon PoS and Opside Chain itself. In Opside's design, developers can deploy ZK-Rollups on the above-mentioned different base chains. With the gradual maturity of ZK-Rollup technology, hundreds of ZK-Rollups may be born in the future, which will bring a huge demand for ZKP computing power. Therefore, we need to incentivize miners to join this ecology to contribute. After switching from PoW to PoS, many Ethereum mining machines have lost their application scenarios. In terms of capital scale, the value of mining machines is 12 billion US dollars, and many of them are currently idle. With the large-scale implementation of ZK-Rollup, the generation of ZKP requires a large number of CPU, GPU, FPGA and other hardware and mining machines to provide computing power.

Opside uses the ZK-PoW mechanism to motivate Miner to provide ZKP computing power, thus providing complete hardware facilities for ZK-Rollup. This is also one of the core ideas of Opside. All roles, including users, developers, and miners, can benefit from this Opside economic model.

Two-step submission algorithm of ZKP: standard decentralized Prover mechanism

• In order to encourage more miners to participate in ZKP computing tasks at the same time, Opside proposed a two-step ZKP verification mechanism. The PoW reward share corresponding to a ZKP will be distributed to valid ZKP submitters, that is, miners, according to certain rules.
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1. Submit proofhash: Within a time window, for a certain sequence, multiple miners are allowed to participate in the calculation of zero-knowledge proof. After each miner calculates the proof, they do not submit the original proof directly, but calculate the proofhash of (proof/address) and submit the proofhash to the contract.
2. Submit ZKP: After the time window, the miner submits the original proof and verifies it with the previously submitted proofhash. Miners who pass the verification can get PoW rewards, and the reward amount is distributed according to the proportion of the miners' pledged amount.

For more details, please refer to ZKP's Two-Step Submission Algorithm

Optimized ZKP generation algorithm: miner efficiency increased by 80%

When Rollup's smart contract verifies ZKP, if the original proof data is submitted, it may trigger an attack on the chain. In order to prevent malicious attacks, ZK-Rollup often requires extra work to hide the original proof data. One solution is that the ZKP submitted by the miner contains the aggregation result of the miner's address. The two-step submission algorithm of ZKP proposed by Opside cleverly adopts the mode of first submission + later verification, and no longer needs to do similar unnecessary aggregation calculations for proof and address.

In addition, in some open source zkEVMs, the calculation and submission of ZKP are serial. When ZK-Rollup submits a large number of sequences, miners cannot calculate multiple ZKPs at the same time. In Opside, the two-step submission algorithm of ZKP realizes the parallel computing and serial submission of ZKP, allowing mining machines to perform multiple ZKP generation tasks at the same time, thus greatly accelerating the generation efficiency of ZKP.

The Opside team also made a series of optimizations to the ZKP recursive aggregation algorithm, which fully improved the utilization of machine resources in the cluster and further improved the calculation speed of ZKP.

In the actual pressure test environment, the miner has a machine cluster consisting of 20 128 core CPU + 1TB RAM, and the test transaction is stable at 27.8TPS for about 40 minutes. Under the same conditions, Opside reduced the average confirmation time of transactions from about 5-6 minutes to about 3 minutes, and increased the efficiency of ZKP generation by about 80%. In the future, with the addition of more ZK-Rollups and miners, the scale of the demand side and supply side of the ZK computing power market will be further expanded, and the efficiency improvement brought by Opside's PoW algorithm will be more obvious.

Opside Chain

As one of the base chains, Opside Chain not only supports Opside ZK-PoW Cloud, but also optimizes ZK-Rollup more. For example, use pre-compiled contracts for ZKP accelerated verification, support data fragmentation, and adopt the PoS consensus based on ETH 2.0. In the future, full sharding schemes such as EIP-4844 and DankSharding will be supported, and the Gas cost of Rollup will be reduced to a minimum, even 0.

Ethereum is now the world's largest decentralized network with more than 500,000 nodes. These nodes not only provide large-scale decentralization, but in the future, thanks to data sharding technology, these more than 500,000 nodes will also provide massive data availability.

Opside Chain is inspired by Ethereum, which is one of the reasons why Opside chose to improve based on the PoS consensus of ETH 2.0. We expect that there will be more than 100,000 nodes on Opside Chain.

For Rollup, how to make the sequencer more decentralized, instead of a single node to complete the centralized packaging? A good practice is to let Opside Chain block proposers propose Rollup Layer blocks at the same time. For Rollup Layer, it actually completes the separation of builder and proposer: the builder is supported by a P2P network without permission, and the proposer follows the block proposer of the Opside chain, thus avoiding the usability risk brought by a single node , but also has a certain resistance to MEV and anti-censorship.

Therefore, Opside Chain provides a standardized decentralized sequencer mechanism, and block proposers of Opside Chain are also responsible for proposing Rollup blocks. Opside Chain allows ZK-Rollup to not only inherit the security of the previous layer, but also inherit the degree of decentralization of the previous layer.

The following is the PoS & PoW hybrid consensus of Opside Chain:

• Opside chain

• PoS: Opside will adopt the PoS algorithm of Ethereum 2.0 and make necessary improvements to it. Anyone can hold Opside tokens and become a validator. The validator can get block rewards and gas fees in the Opside chain.

• Rollup layer

• PoS (Sequencer): The validator not only proposes Opside chain blocks, but also proposes Rollup layer blocks (ie data batch). Therefore, the validator is also the sequencer of the rollup in the Rollup layer. The sequencer can earn gas fees from the transaction fees in Rollup layer transactions.
• PoW (Prover): Anyone can become the prover of the rollup in the Rollup layer, as long as it has enough computing power for ZKP calculation. According to the PoW rules, the prover generates zk proofs based on the Rollup layer blocks submitted by the sequencer.

A ZK-Rollup is similar to a computer. A computer has two core components, one is the hard disk and the other is the CPU. The data availability provided by PoS is equivalent to a hard disk, and the computing power provided by PoW is equivalent to a CPU. What Opside Chain needs to do is to find a balance between PoS and PoW, so that each role can give full play to its value and benefit from it, so that the large-scale ZK-Rollups network can have better performance and experience.

Token supply and demand

Opside token is called IDE, and IDE will be issued in the form of PoS and PoW rewards, corresponding to Validator and Miner respectively. In the Pre-Alpha testnet stage, the block reward ratio between PoS and PoW is temporarily fixed at 1:2. In the future, the ratio of the two will be dynamically adjusted with the supply and demand of the ZKP computing power of the entire network.

PoS

As mentioned above, Opside Chain adopts the improved PoS consensus based on ETH 2.0. To participate as a Validator, users must deposit a certain amount of IDE into the deposit contract and run three separate pieces of software: the execution client, the consensus client, and the Validator. These Validators are responsible for checking that new blocks propagated through the network are valid, and occasionally create and propagate new blocks themselves. If the Validator behaves dishonestly or lazy, the staked IDE will be destroyed as collateral.

Under PoS, Opside Chain's block production speed is fixed, and the time is divided into slot (12 seconds) and epoch (32 slots). A validator is randomly selected in each slot as the block proposer. This Validator is responsible for creating new blocks and sending them to other nodes on the network. Also in each slot, a Validator committee is randomly selected whose votes are used to determine the validity of the proposed block. Please refer to ETH PoS for the specific mechanism.

Opside Chain expects to support EIP-4844 on the Alpha test network, and Data Availability Sampling (DAS) will be used to ensure that ZK-Rollup provides its transaction data after execution without causing too much pressure on any single node. Each Validator randomly samples the transaction data provided in the blob to ensure all data is present. The same technique can also be used to ensure that block producers provide all their data to secure light clients. Likewise, under proposer-builder separation (PBS), only block builders are required to process entire blocks - other validators will use data availability sampling for validation.

In some specific parameters, Opside will be different, and readers can find the latest values in the code base.

Overall, staking makes it easier for individuals to participate in securing the network, promoting decentralization. Validator nodes can run on regular laptops. Some proxy staking pools even allow users to stake without having enough IDE.

ZK-PoW

Based on the ZK-Rollup launchbase provided by Opside, developers can choose to have an exclusive ZK-Rollup on a base chain. In order to support the demand for massive hardware resources brought by a large number of ZK-Rollups, Opside provides a unified ZKP computing power market and encourages miners (that is, provers) to generate ZKP for these ZK-Rollups. This is Opside's ZK-PoW mechanism.

Reward share calculation for a single Rollup sequence

ZK-PoW is a multi-chain protocol, which means that PoW rewards will be issued on various base chains, including Etheruem, Opside Chain, BNB Chain, and Polygon PoS. The number of PoW rewards for each base chain depends on the number of corresponding Rollup slot registrations, ZKP workload, etc.

For each base chain, within a block, each Rollup can only submit one sequence (multiple blocks of the Rollup can be included). Each sequence equally shares the PoW reward of the current block. This means that if 4 Rollups submit sequences in a block of the base chain, the PoW rewards will be equally divided into 4 shares, and the rewards for each sequence will be 1/4 of the block PoW rewards. Of course, there may not be any Rollup submission sequence in some blocks, so the actual inflation of PoW may be lower than expected.

In the future, each sequence will estimate the workload based on the corresponding ZK-Rollup type, the number of Rollup transactions involved, the amount of gas usage, etc., so that different sequences will be priced differently.

Prover's Pledge and Punishment

In order to avoid prover-related malicious behavior, Prover needs to be registered in a special system contract and pledge tokens. Prover can freely choose to participate in the PoW mining of one or more Rollups. Prover needs to pledge a certain amount of IDE (Opside token) for each Rollup to participate in the system contract before submitting ZKP for the Rollup. If the current pledge amount is less than the threshold, ZKP is not allowed to be submitted for the Rollup. The rewards obtained by the prover for submitting ZKP will also be distributed according to the proportion of the pledged amount, so as to avoid the malicious behavior of the prover submitting ZKP multiple times.

When the prover has the following behaviors, different degrees of punishment will be imposed:

• If the prover submits the wrong hash
• If no ZKP passes the verification, all provers who have submitted the hash will be punished

Forfeited Opside tokens will be burned.

For more details and considerations about ZKP's two-step commit mechanism, please refer to the official documentation. The specific numbers of prover pledges and penalties may change in the future.

Developer leases Rollup slot

On each base chain, Opside has deployed the ZK-PoW protocol. Developers can register a Rollup slot through the ZK-Rollup launchbase with one click, thereby launching their own ZK-Rollup. All hardware resources of the ZK-Rollup are provided by the Opside decentralized network. Developers need to pay the rent of the Rollup slot to the Opside network, and this part of the rent will be burned directly.

In addition to a fixed amount of rent, developers can also provide additional ZKP subsidies for their own ZK-Rollup to motivate miners to provide computing power.

Readers can find specific rent and subsidy rules and parameters in official documents or code libraries.

Governance and Development

The functionality and performance of the Opside network will continue to evolve over time, here are a few examples of higher priorities:

• Dynamically adjust the reward distribution ratio of PoS and PoW according to the supply and demand relationship of ZKP computing power in the entire network
• Validator's data fragmentation and data availability sampling will provide more abundant storage space for the entire Rollup Layer, thereby accommodating more ZK-Rollup ecology
• The Rollup proposer is separated from the builder, so that the Rollup layer shares the validator of the Opside chain as the block proposer, inheriting the decentralization of the previous layer
• The optimization of miners' pledge and slash mechanism encourages miners to provide continuous and stable ZKP computing power
• Application developers subsidize the ZKP generation of their Rollup to encourage miners to provide computing power
• Estimate the workload based on ZK-Rollup type, Rollup transaction quantity, gas usage, etc., and establish a personalized pricing mechanism for Rollup batch

These improvements will significantly increase Opside's network utility, thereby promoting the long-term development and prosperity of ZK-Rollup as a Service.

After the Opside main network is launched, an Opside DAO will be established, including reasonable processes and mechanisms to jointly determine the future of the network. The update of all parameters and mechanisms of the Opside mainnet will be determined through the Opside DAO. It is important to emphasize that Opside is a collaborative economy that evolves over time.