New Direction for Bitcoin Lightning Network Development: Analysis of Thunderbolt Protocol

Bitcoin, as the pioneer of digital currency, has long been a topic of controversy regarding the speed and efficiency of its main chain transactions. Despite the advantages of decentralization and immutability, Bitcoin faces many challenges in everyday payment scenarios. For example, the time spent waiting for transaction confirmation can sometimes be longer than waiting for coffee, and at times the transaction fees even exceed the price of the coffee itself. This limitation makes Bitcoin assets difficult to utilize flexibly, preventing functionalities like loans, combinations, or interoperability.

The script structure design of Bitcoin is relatively conservative, limiting most off-chain interaction scenarios. However, there is still a demand from users for fast and convenient Bitcoin payments. To address this issue, the Lighting Network was born.

The Lighting Network attempts to increase transaction speed and reduce fees by establishing a payment channel network outside the Bitcoin main chain. However, this solution also has many problems. First, establishing payment channels requires locking funds in advance, which poses a high barrier for users. Second, complex routing issues may lead to transaction failures. Finally, security risks cannot be ignored, and users need to stay online to prevent fraudulent activities.

Although the Lighting Network has been running for many years, its actual application scale is still limited. Currently, the total amount of funds locked in the Lighting Network is only about $100 million, which is insignificant compared to the trillion-dollar market value of Bitcoin. This prompts the industry to ponder: is there a more完善的 off-chain payment protocol to break through the current predicament?

In this context, the Bitcoin Thunderbolt protocol was born. This is a soft fork upgrade plan based on the Bitcoin base layer, which directly improves the main chain protocol level, aiming to enhance Bitcoin's scalability, transaction performance, and programmability.

The core innovations of the Thunderbolt protocol include:

1. UTXO Bundling technology: By aggregating multiple UTXOs, transaction speed is increased by about 10 times.

2. Extended OP_CAT opcode: Enhances the expressiveness of Bitcoin scripts, supporting more complex smart contract logic.

3. Goldinals Unified Asset Standard: Based on zero-knowledge proofs and state commitments, it realizes the Bitcoin native token standard.

4. BitMM On-chain Automated Market Maker: Integrating protocol assets such as BRC-20, Runes, and Ordinals.

5. BitVisa decentralized identity and credential system.

Thunderbolt adopts the "native chain expansion" approach, with all functions running directly on the Bitcoin main chain, using native BTC instead of cross-chain mapped tokens.

From a technical standpoint, the core mechanism of Thunderbolt includes:

1. Flexible and adjustable multi-signature: Split the signature into user and committee parts, achieving secure transfer through secret sharing.

2. Asynchronous fault-tolerant committee ledger: A service group composed of multiple nodes is responsible for accounting, ensuring system stability and decentralization.

3. Atomic swap finalization: Ensure the consistency of off-chain reconstruction and on-chain redemption through a three-step atomic swap.

Key innovations of Thunderbolt also include:

• Non-interactive, recursive signature delegation
• Each transfer uses a "new lock"
• Leave a mark on the chain only once
• You won't lose money even offline.
• True "proof of machine" security

Compared to existing Lightning Network solutions, Thunderbolt has advantages in security and theoretical completeness. However, it also faces challenges such as deployment complexity, main chain compatibility issues, and insufficient ecological support.

Looking ahead, the possible development paths for Thunderbolt include:

1. Integrated as a Rollup, serving as the DeFi engine on the Bitcoin side.

2. Form an independent standard ecosystem that runs in parallel with the main chain.

3. Replaced by a simpler solution.

The greatest significance of Thunderbolt lies in introducing "off-chain contract composability" for Bitcoin assets. Through the two key features of UTXO Bundling and OP_CAT, Thunderbolt brings native programmability and higher transaction throughput to the Bitcoin network. Although it is still in the theoretical research stage, Thunderbolt offers new possibilities for the future development of the Bitcoin ecosystem.