GOAT launches real-time ZK Rollup Testnet: New possibilities for native BTC yield?

Seeing the GOAT network launch its Testnet based on BitVM2 technology, there is an implementation worth following: real-time proof of Bitcoin ZK Rollup. The implementation of fast ZK Rollup proof is an important development for the infrastructure of BTC L2. From the user experience perspective, there will be a significant efficiency improvement in withdrawal times compared to before, which is beneficial for attracting more developers and user attention.

So, how can we simply understand it from a technical perspective?

First, let's take a look at the implementation process of Bitcoin L2 on the GOAT network. The GOAT network is a Bitcoin L2 solution that utilizes BitVM2 and zkMIPS technologies, supporting the generation of native BTC rewards (meaning participants have the opportunity to earn more BTC). Its process mainly includes Bridge in, Bridge out, Sequencer Set Commitment, and Reimbursement, among others. Bridge in mainly involves staking BTC into a taproot script (with no controlling private key), and the relayer submits it to Goat's contract. The committee constructs the BitVM2 transaction flow, the operator pre-signs and stores it on IPFS, and after user verification, the relayer issues PegBTC on L2; Bridge out is for withdrawal, where users perform atomic transactions with the operator (users can also be operators themselves, but if they prefer not to, they can complete the withdrawal through the operator), destroying PegBTC on L2, and the operator initiates the reimbursement process without needing to perform Peg-OUT transactions on the BTC main chain. Sequencer Set Commitment mainly refers to the committee regularly using a Merkle tree to commit to future sequencer sets, supporting the verification of Bitcoin light client mechanisms. The verification of the committed validator set on BTC using the light client mechanism serves as public input for subsequent zero-knowledge proof verification, facilitating the validation of L2 block consensus. Reimbursement processing involves the operator staking BTC and submitting the transaction ID for withdrawal along with the latest block hash. Challengers perform off-chain and on-chain verification, and if there are no challenges, the operator receives the funds. Challengers can also raise challenges; after a challenge occurs, validators are randomly generated, and validators can execute interactive verification through Bitcoin scripts. The challenge period is shortened to about 1 day (approximately 144 BTC blocks), compressing the time required for finality. Additionally, it utilizes a decentralized sequencer, where operators stake BTC to participate, and the economic model generates native BTC rewards, including L2 gas fees.

Let’s focus on the real-time proof of ZK Rollup, starting with its Rollup technology. The GOAT network will package multiple L2 transactions into batches, execute them off-chain to generate a ZK proof, which will be verified through the Bitcoin main chain (such as in the Assert/Disprove phase of BitVM2). The advantage of ZK proof is that it does not require uploading all transaction details; moreover, unlike Ethereum's zksync or Starknet, Goat uses Bitcoin Taproot scripts and other native mechanisms to anchor state updates, thereby avoiding reliance on external bridging or multi-signature mechanisms.

Now that we have a simple understanding of its Zk Rollup technology, let's take a look at its real-time proof mechanism. According to the GOAT network documentation, its real-time proof generation utilizes the zkMIPS engine, achieving fast proof generation through a pipelined parallel proof architecture and a distributed GPU prover network. First is the block proof generation, which uses execution trace sharding and parallel proof techniques to verify whether the Rollup state transitions are correct; second is the aggregation proof, which recursively compresses multiple block proofs; finally, the SNARK proof (Groth16), which is compressed into a small verifiable proof on BitVM2.

In order to achieve real-time proof, the proof generation mentioned above is not processed in a single-line manner, but rather uses a pipelined parallel processing mechanism, mainly relying on ZKM's zkVM "Ziren" technology to implement it, along with GPU acceleration and a distributed network of provers. According to the current official website data of its testnet, block proofs take approximately 2.6 seconds on average, aggregate proofs take about 2.7 seconds on average, and SNARK proofs take around 10.38 seconds. Users can view the complete ZK proof generation process for each withdrawal in real-time through the front-end page.

If the ZK proof can be completed in less than 1 minute, it means that the speed of user withdrawals will be greatly accelerated. Previously, some Bitcoin L2 network withdrawals had to wait several hours to initiate. With the fast proof, users can initiate withdrawals immediately after the proof is generated, which means that users can initiate withdrawals in about less than 1 minute. Of course, the final arrival time for users still depends on the transaction situation of the Bitcoin mainnet. However, in terms of withdrawals, there is no need to wait, which means that the withdrawal experience is basically close to the time it takes to initiate a transaction on the Bitcoin chain.

In addition to withdrawals, real-time proofs will also promote developers to build high-frequency L2 applications. Moreover, compatibility with EVM can attract developers from the Ethereum ecosystem. For operators, there is no need to wait for batch proofs, which can also improve capital efficiency. ZK technology is relatively complex, and long-term security requires some time to prove. However, the implementation of real-time proofs is an important technological infrastructure advancement for Bitcoin L2. Of course, Bitcoin L2 still has a long way to go. In addition to building technical infrastructure, more efforts are needed to explore user needs and promote developers to build Bitcoin L2 applications. Ultimately, only when the Bitcoin L2 ecosystem is established will there be sufficient transaction fees to achieve the growth of the flywheel. One relatively clear demand is that many BTC holders also hope to earn returns, which can be seen from the number of BTC on the Ethereum chain (such as wbtc, etc.), with currently over 150,000 BTC wrapped on the Ethereum chain, valued at over 15 billion dollars. If native security based on the BTC chain can be achieved, then more BTC holders would be willing to try to earn returns through BTCFI.