Written by: Haotian
In short, the GOAT network proposes a decentralized and secure Bitcoin layer2 solution based on the BTC script locking native security mechanism provided by the Optimistic Challenge Proof (OCP) and the interoperable unified liquidity settlement layer provided by the ZKM Entangled Rollup. How to do it specifically?
Due to the natural limitations of the BTC mainnet scripting language, it is impossible to use conventional ZK Proof of Validity to ensure the immediate finality of cross-chain asset deposit and withdrawal transactions. This means that common Bitcoin Layer 2 expansion solutions require a "third-party trusted entity."
To address this issue, Babylon provides a unique cross-chain security model that combines multiple technologies such as time locks, one-time signatures (EOTS), and multi-signature consensus.
However, Babylon’s design relies on the main network to provide security, and is more like a shared security layer. Compared with the traditional layer2 expansion solution that executes transactions on the second layer, this type of security consensus lacks a second-layer ledger and a verification mechanism for the second-layer ledger on the first layer. If Layer2 relies too much on Babylon’s solution, it will lose security control over its own chain. Therefore, Babylon prefers some asset management expansion solutions rather than common general security solutions.
Goat Network is positioned as a more general decentralized second-layer expansion solution with native security cross-chain features.
Its Native cross-chain mechanism implements an Optimistic Challenge Protocol based on the BitVM2 idea. All calculations and interactions are performed offline on the second layer. When a "challenge" occurs, the on-chain protocol will be executed on the Bitcoin mainnet, and Bitcoin layer1 will act as an arbitrator to ensure security.
in particular:
1) The assets that users deposit (Peg-in) in layer2 will first be managed by the GOAT network fund pool and locked in an n-of-n Bitcoin multi-signature script;
2) When a user initiates a withdrawal (Peg-out) on layer2, the GOAT network node Operator will immediately transfer the assets to the user, which is equivalent to an “advance payment”;
3) After completing the payment, the Operator will initiate a transaction containing a challenge script and an asset script to the GOAT network fund pool, requesting that the assets paid by the Operator, as well as the corresponding rewards and handling fees, be transferred to the node account;
4) To prevent node operators from doing evil, a challenge mechanism is introduced. Any user can pay a certain amount of BTC assets to call the challenge script. If the challenge is successful, the node operator's behavior is proven to be dishonest, the node's withdrawal request will be invalid, and the corresponding assets pledged will be transferred to the challenger's account. If the challenge is unsuccessful, after a certain period of time, the node operator will receive all assets including prepaid fees;
In layman's terms, GOAT Network is equivalent to building a middleware network protocol based on Entangled Rollup. Every time a user deposits or withdraws an asset, it is "advanced" by a node on the Entangled Rollup network. The user side is absolutely secure, while the node side uses the challenger mechanism (OCP) to eliminate the possibility of potential malicious behavior. For example, the node Operator constructs a fake withdrawal user to extract legitimate funds from the real user's funding pool.
This is different from the challenge idea provided by BitVM2. BitVM2 is based on a NAND circuit solution and uses logic gate commitment to track transactions and the Bisection protocol to conduct challenges. This process is limited by the size of the Bitcoin mainnet script. If the constructed transaction is more complex, the efficiency will be lower.
GOAT Network implements SNARK proof based on ZKM and uses Winternitz signature for optimization, so that the smallest Taproot storage unit can be achieved to verify the script validity of the Bitcoin mainnet.
The OCP challenger proof mechanism can ensure that the user's asset pool is safe and protected by the "arbitration" of the Bitcoin mainnet. However, in most cases, users execute transactions on BTC layer2, and the second-layer sequencer is responsible for verifying and sorting transactions. There are still various potential security risks such as MEV and downtime. Therefore, the GOAT network also implements the decentralization of the sequencer based on the BTC script locking and one-time signature mechanism to further consolidate the security trust mechanism.
Previously, I wrote an article specifically analyzing the Entangled Rollup protocol, which is a unified interoperability layer that can realize asset and message passing between node operators, while using a decentralized security governance mechanism to ensure security.
In summary, GOAT Network provides the foundation for its role as a universal Native cross-chain Bitcoin Layer 2 solution through the OCP Challenger Mechanism and Entangled Rollup unified interactive layer.
Note: The above interpretation is only the basic technical logic and framework. For more details, please read the white paper in detail to learn more about: 1) How to apply the OCP challenger mechanism and optimize the implementation effect of BitVM2; 2) How to achieve cross-chain unified liquidity with Entangled Rollup; 3) ZKM performance optimization details in the implementation of Bitcoin script functions, etc.
