How does CKB implement L2 without cross-chain bridges?

Inscriptions have created many new assets, but their application has stopped at issuing assets.

But its wealth effect and FOMO allow people to see the imagination of the BTC ecosystem. In the actual needs of players on the chain, various restrictions on the Bitcoin network and UTXO have further stimulated people's demand for Bitcoin expansion and more complex ecological applications.

From a scaling perspective, the Lightning Network is already a great enough L2. Lightning channels achieve trustlessness through games (punishment-based revocable commitment transactions) and have been running for many years. However, the state channel architecture of the Lightning Network is basically limited to payment and cannot achieve more complex intentions.

Implementing a relatively safe and elegant L2, adopting a UTXO model that is isomorphic to BTC, and extending it using the eUTXO concept may be a way out. Both public chains Ergo and Cardano have made achievements in the eUTXO model and have implemented smart contract functions. But it was CKB that first thought of implementing an L2 solution.

CKB’s answer is to propose an extension protocol for RGB: RGB++. In fact, it is not so much an extension as it is a “big magic change”. The extension of CKB inherits the core of the RGB protocol, but directly uses different virtual machines and verification schemes. As an open source smart contract system protocol, the RGB protocol is designed to run scalable, robust and private smart contracts on UTXO blockchains (such as Bitcoin, Liquid). Currently v0.11 has not been released, and its virtual machine AluVM is still far away from being fully implemented (some say it may not be possible even after this bull market is over)

Its technical focus is "isomorphic binding", which maps Bitcoin UTXO to Nervos CKB's Cell - a modified version of UTXO that can be combined to implement smart contract capabilities. For the verification scheme, all RGB++ transactions will appear simultaneously on the BTC and CKB chains with one transaction each. The original off-chain client verification has been changed to CKB's on-chain public verification, which is much more user-friendly. There is no need to use an independent client or save the original transaction data.

A rough understanding is that RGB++ assets issued on the first layer of Bitcoin can use smart contracts on the second layer of ckb to achieve various complex intentions.CKB does not use any cross-chain bridge, but uses a native client verification scheme