Explore the three possibilities of ZK-Rollups in Bitcoin expansion

Author: Hacash Enthusiast

ZK-Rollups have become one of the most promising scaling technology solutions on Ethereum. Its representative projects zkSync and StarkWare announced that the amount of financing has exceeded 100 million US dollars. As Bitcoin expansion gradually becomes the next major narrative in the encryption industry, it is particularly important to explore the possibility of combining ZK-Rollups with Bitcoin.

Before we start exploring, let us first clearly sort out the technical concept of ZK-Rollups in Bitcoin expansion in this article.

These concepts can be divided into three main areas:

1. Stored ZK-Rollups data

ZK-Rollups must run verification code on a layer of Bitcoin and store the resulting data. Those that only store the ZK-Rollups finalized state data root (Merkle root) on the Bitcoin layer are not considered real solutions.

For example, the Sovereign Rollup solution similar to the Bitcoin expansion project Rollkit only stores state data on the Bitcoin chain. However, the scheme was ridiculed by Ethereum KOL ryanb.eth immediately after its launch.

Storing state data on the Bitcoin layer is currently the easiest way to implement ZK-Rollups, but this approach lacks real meaning. Committing and storing state data on the Bitcoin layer is just a self-certifying act and does not constitute a complete solution.

2. Turing complete ZK-Rollups

Achieving EVM-compatible ZK-Rollups requires support for Turing-complete smart contracts at the Bitcoin layer to handle various types of ZK verification. This ZK-Rollups scheme that requires smart contract verification is an imaginative and promising technical goal, but the current progress still has many uncertainties, involves a lot of necessary basic research and development work, and is still in the exploratory stage.

3. Customized ZK-Rollups

For some limited and fixed scenarios, such as payment requirements, customized ZK-rollups technical solutions can be developed. The functional logic of this type of scheme is relatively clear and simple. In most cases, Turing's complete smart contract support is not required, and it can be implemented by hardcoding at the Bitcoin layer.

This particular class of ZK technology has the potential to evolve into an underlying technical component, similar to how elliptic curve cryptography became the cornerstone of blockchains.

After determining the three aspects of ZK-rollups in Bitcoin expansion, we can conduct a global exploration and summary of the various possibilities and potential problems of the combination of Bitcoin and ZK-rollups based on the three aspects.

After clarifying the technical concept of ZK-Rollups in Bitcoin expansion, we can comprehensively explore and summarize the various possibilities and potential problems of the combination of Bitcoin and ZK-rollups based on these three aspects.

1. The first layer of Bitcoin supports Turing's complete ZK-Rollups

Supporting the Turing-complete ZK-Rollups route would mean a huge upgrade to the Bitcoin mainnet. After the upgrade, various applications on ZK-rollups will be able to enjoy the decentralization and security of the Bitcoin network, and improve the sustainability of the Bitcoin network economic model to a certain extent.

However, it also means that the currency and store-of-value narrative that Bitcoin has insisted on will change, bringing it closer to Ethereum. At the same time, the large block route represented by Bitcoin Cash (BCH) may re-emerge, because Bitcoin's network decentralization will be weakened, and the core narrative and the value foundation it is based on will be questioned.

The challenge in this direction lies in the need to upgrade the Bitcoin mainnet. This means that the vast majority of Bitcoin developers, miner groups, large Bitcoin users, and relevant market institutions need to reach a consensus and unify the upgrade actions of all nodes. Otherwise, we can only adopt a solution similar to BIP 300/301 proposed by LayerTwo Labs, that is, directly fork the Bitcoin main network, and expect the consensus of the Bitcoin community to upgrade through the subsequent performance of the forked chain.

2. ZK-Rollups optimization of specific aspects of Bitcoin

Regardless of whether Bitcoin is upgraded to support Turing's complete ZK-rollups, it does not affect the technical optimization of ZK technology in specific aspects of Bitcoin. If Bitcoin does not upgrade to support Turing's complete ZK-rollups, it only performs technical optimization in specific scenarios, which means that the core narrative of Bitcoin currency and value storage can continue to be retained.

For example, in terms of payment, ZK-rollups can use mathematics rather than economics to bring about higher efficiency than the Lightning Network, but this will bring greater computing consumption and increase the cost of node operation. When other existing technical solutions can achieve similar results, the market tends to favor the technical solution with lower overall cost.

The possible challenge of this direction is whether there are enough specific scenarios for Bitcoin that need to adopt ZK-rollups, and whether ZK-rollups can achieve the optimal efficiency and cost. Otherwise, there is a suspicion that the project will issue coins purely through technical narratives .

Regardless of whether Bitcoin is upgraded to support Turing-complete ZK-rollups, it will not affect the technical optimization of ZK technology in specific aspects of Bitcoin. If Bitcoin is not upgraded to support Turing-complete ZK-rollups, but only technically optimized in specific scenarios, this means that Bitcoin can continue to retain its core narrative as a currency and store of value.

For example, in the field of payment, ZK-rollups can bring higher efficiency than Lightning Network through mathematical methods rather than economic methods, but this will increase computing costs and increase node operating costs. When there are other existing technical solutions that can achieve a similar effect, the market usually prefers the technical solution with lower overall cost.

The challenge in this direction is to determine whether there are enough specific scenarios for Bitcoin that require ZK-rollups, and whether ZK-rollups can achieve optimal efficiency and cost. Otherwise, the project may only conduct coin issuance hype through technical narratives, which requires vigilance.

3. Bitcoin compatible chain supports ZK-Rollups

Due to the extremely high difficulty of advancing the ZK-Rollups upgrade that supports Bitcoin Turing's completeness, it faces the risk of Bitcoin narrative collapse. In addition, the scaling of Bitcoin-specific ZK-rollups has cost issues in the long run. Therefore, the possibility of transferring Bitcoin to a compatible chain for ZK-Rollups expansion is very high.

At present, the Bitcoin compatible chain supports ZK-rollups mainly in two ways: side chain and one-way transfer to the new chain.

ZK-Rollups side chain method

The sidechain solution has already represented a direction in the field of Bitcoin expansion. These sidechain projects generally use specific cross-chain technology to transfer Bitcoin to a chain that supports EVM for expansion. Further scaling effects can be achieved by adding ZK-rollups on these chains.

At present, there are already multiple side chains in the direction of Bitcoin ecological expansion, such as Stacks, RootStock, and Liquid Network. Therefore, the possibility of this direction will depend on whether future competitors lead the way by adding ZK-Rollups to existing sidechains, or by brand new, ZK-Rollups-focused sidechains.

ZK-Rollups one-way transfer method

The expansion scheme for one-way transfer of Bitcoin is mainly proposed by the project Hacash. The basic principle is to unidirectionally transfer Bitcoin from the main network to a new chain, and support ZK-rollups on the new chain for expansion.

These two methods of supporting ZK-rollups in Bitcoin-compatible chains require sufficient incentives to promote the transfer of Bitcoins to the chain, but the biggest difference lies in whether the transferred Bitcoins can be returned to the main network. Therefore, in order to make ZK-rollups one-way transfer more possible, it is necessary to solve the problems existing in the ZK-rollups sidechain method, and preferably also have some new advantages.

The key problem in the side chain expansion method is how to achieve sufficient decentralized management of the Bitcoin cross-chain process. At present, almost all methods based on traditional cross-chain bridges have various centralization defects. The one-way transfer method is realized by maintaining the invariance of the private key before and after the Bitcoin transfer, without introducing any form of management center, so there is no need for a cross-chain bridge in the traditional sense.

In addition, the advantages that the one-way transfer method does not have over the ZK-Rollups sidechain method should also be considered. Taking Hacash as an example, based on Hacash's first-layer PoW decentralization mechanism and self-regulating currency supply stability system, it can improve the lack of currency attributes of Bitcoin.

Summarize

There are three main possibilities for the combination of Bitcoin and ZK-rollups: Bitcoin supports Turing-complete ZK-Rollups, ZK-Rollups optimizes Bitcoin-specific functions and scenarios, and Bitcoin-compatible chains support ZK-Rollups.

To realize that Bitcoin supports Turing-complete ZK-rollups, broad support from the entire community is required. However, this could trigger a Bitcoin Core narrative crisis.

The optimization of ZK-Rollups for Bitcoin-specific functions and scenarios needs to be evaluated on a case-by-case basis. If other solutions already exist, you need to weigh the cost of ZK-rollups.

Bitcoin-compatible chains support ZK-rollups, which can be implemented in two ways: side chains and one-way transfers. Either way, there needs to be enough incentives to attract bitcoin participation. The side chain method needs to focus on the competition between existing and emerging projects, while the one-way transfer method needs to solve the problem of centralization of management and have advantages in other economic models to increase the possibility of its success.

The above is a summary of the three main possibilities for the combination of Bitcoin and ZK-rollups.