The GOAT Network launched its BitVM2-based testnet, featuring a noteworthy implementation: real-time Bitcoin ZK Rollup proofs. Achieving fast ZK Rollup proofs is a significant development for the BTC Layer 2 infrastructure. From a user experience perspective, withdrawal times will be significantly improved, which will attract more developers and users.

So, how can we understand this from a technical perspective?

First, let's take a look at the GOAT Network's Bitcoin Layer 2 implementation. The GOAT Network is a Bitcoin Layer 2-based solution that utilizes BitVM2 and zkMIPS technology, supporting native BTC yields (meaning participants have the opportunity to earn more BTC). Its process primarily includes bridge-in, bridge-out, sequencer set commitments, and reimbursement. Bridge-in involves staking BTC into a taproot script (private keys controlled by no one), which relayers then submit to the GOAT contract. The committee constructs the BitVM2 transaction flow, which is pre-signed by the operator and stored on IPFS. After user verification, the relayer issues PegBTC on L2. Bridge-out involves withdrawals, where users conduct atomic transactions with the operator (the user can also be the operator; if they prefer, they can withdraw through the operator). The PegBTC on L2 is destroyed, and the operator initiates reimbursement, eliminating the need for a Peg-out transaction on the BTC mainchain. Collator commitments primarily involve the committee periodically using Merkle trees to commit to the future set of collators, supporting verification by Bitcoin light clients. Verification through light clients uses the committed validator set on BTC as public input for subsequent zero-knowledge proof verification, thereby verifying L2 block consensus. Reimbursement involves the operator staking BTC and submitting the withdrawal transaction ID and the latest block hash. Challengers conduct both off-chain and on-chain verification. If no challenge is received, the operator receives the funds. Challengers can also issue challenges. After a challenge is issued, a random validator is generated, which can then perform interactive verification via Bitcoin Script. This shortens the challenge period to approximately one day (approximately 144 BTC blocks), shortening the time required for finality. Furthermore, it utilizes a decentralized sorter, with operators staking BTC to participate. L2 gas fees and other factors in the economic model generate native BTC revenue.

Now, let's focus on its real-time proofs, ZK Rollup. First, let's discuss its Rollup technology. The GOAT network bundles multiple L2 transactions into batches, executes them off-chain, and generates a ZK proof. This proof is then verified on the Bitcoin mainchain (e.g., through BitVM2's Assert/Disprove phases). The advantage of ZK proofs is that they don't require uploading all transaction details. Furthermore, unlike Ethereum's zksync or Starknet, GOAT uses native mechanisms like Bitcoin's Taproot script to anchor state updates, avoiding reliance on external bridges or multi-signature mechanisms.

Now that we've briefly reviewed its ZK Rollup technology, let's take a look at its real-time proof mechanisms. According to the GOAT network documentation, its real-time proof generation utilizes the zkMIPS engine, utilizing a pipelined parallel proof architecture and a distributed GPU prover network to achieve rapid proof generation. First, block proof generation uses execution trace sharding and parallel proof technology to verify the correctness of Rollup state transitions. Second, aggregate proof generation recursively compresses multiple block proofs. Finally, SNARK proofs (Groth16) are compressed into a small, verifiable proof on BitVM2.

To achieve real-time proofs, these proof generation steps are not handled in a single process, but rather through a pipelined, parallel mechanism. This relies primarily on ZKM's zkVM "Ziren" technology, coupled with GPU acceleration and a distributed network of provers. According to the official testnet website, block proofs average approximately 2.6 seconds, aggregate proofs average 2.7 seconds, and SNARK proofs approximately 10.38 seconds. Users can view the complete ZK proof generation process for each withdrawal in real time on the front-end page.

If ZK proofs can be completed in less than a minute, user withdrawals will be significantly accelerated. Previously, some Bitcoin L2 withdrawals required several hours to initiate. With fast proofs, users can initiate withdrawals immediately after the proof is generated, meaning they can withdraw in less than a minute. Of course, the final arrival time of funds will still depend on the transaction status of the Bitcoin mainnet. However, withdrawals will no longer require a wait time, essentially matching the time it takes to initiate transactions on the Bitcoin chain.

In addition to withdrawals, real-time proofs will encourage developers to build high-frequency L2 applications. Furthermore, EVM compatibility will attract developers from the Ethereum ecosystem. For operators, eliminating the need to wait for batch proofs will improve capital efficiency. ZK technology is relatively complex, and long-term security will require time to prove. However, the implementation of real-time proofs is a significant advancement in the technical infrastructure of Bitcoin L2. Of course, Bitcoin L2 still has a long way to go. Beyond building the technical infrastructure, further effort is needed to explore user needs and encourage developers to build Bitcoin L2 applications. Ultimately, only when the Bitcoin L2 ecosystem flourishes can sufficient transaction fees be generated to achieve flywheel growth. One clear demand is that many BTC holders also desire returns. This is evident in the number of BTC on the Ethereum chain (such as WBTC). Currently, over 150,000 BTC are held on the Ethereum chain, valued at over $15 billion. If the native security of the BTC chain can be achieved, more BTC holders will be willing to try to earn returns through BTCFI.