Due to the poor performance of the TGE batch of Bitcoin L2 in the cryptocurrency secondary market, many market participants such as retail investors, hairdressers, investment researchers, and VCs have turned their attitude towards this track from despair to hostility. But I want to say that the technological and narrative evolution of this track still maintain considerable vitality. In the current stablecoin super cycle, stablecoin infrastructure and DeFi financial abstraction layers based on Bitcoin programmability are popular in the primary market. After almost two years of paradigm competition and iterative optimization, the BitVM2+ZK Rollup solution represented by BoB Network and Goal Network is becoming the standard paradigm for Bitcoin L2. Two Bitcoin OG developers from the Hemi team of the Bitcoin L2 project have proposed a solution with a different approach: Proof of Proof (PoP) Hemi's PoP mechanism embeds Layer 2 consensus state data (L2 Keystones) into Bitcoin blocks, ensuring that any attempt to restructure Hemi state requires a 51% attack on the Bitcoin network. The core components of Hemi's architecture include Bitcoin Finals Governors (BFG) responsible for ensuring transaction finality, Bitcoin Secure Sequencers (BSS) responsible for secure sorting, PoP miners verifying transactions and embedding Bitcoin blocks, Challengers monitoring and verifying transaction correctness, and modified Geth nodes processing Ethereum transactions. Based on the above architecture, Hemi's block production process is as follows: BSS generates new Hemi blocks and broadcasts them → Block heads are sent to BFG → BFG forwards them to PoP miners to construct Bitcoin transactions → Miners return signed transactions to BFG and broadcast them to the Bitcoin network → BFG generates PoP transactions containing proofs → After about 9 Bitcoin confirmations (about 90 minutes), finality is achieved. The brilliance of this design lies in lending the PoW security of Bitcoin to Layer 2. Each L2 Keystone contains the complete state commitment of the Hemi network at a certain point in time. Currently, 1905824 Keystones have been processed, and the final confirmation of 2.78M Bitcoin security guarantee TX has been completed. Each Keystone is a secure anchor that firmly ties the state on Hemi L2 to Bitcoin, the most secure L1. Hemi's execution layer hVM virtual machine allows developers to create smart contracts that are compatible with both Bitcoin and Ethereum, supporting "Bitcoin aware applications" (hApps) while maintaining backward compatibility with existing EVM tools and wallets. The technical challenge of this design is enormous. Bitcoin uses the UTXO model, while Ethereum uses the account model; The scripting language of Bitcoin is non Turing complete, while EVM is Turing complete; The state representation, transaction format, and signature algorithm of the two are completely different. HVM needs to achieve seamless state synchronization and interaction while maintaining the native characteristics of both. HVM runs a complete Bitcoin node instance and synchronizes the Bitcoin network status in real-time. At the same time, it expands the opcode set of EVM and adds Bitcoin aware instructions. This means that smart contracts can directly query Bitcoin UTXOs, verify Bitcoin transactions, and even monitor the generation of Bitcoin blocks. We know that traditional cross chain bridges are essentially a custody scheme - assets are locked onto the source chain and corresponding representative tokens are issued on the target chain. The biggest DeFi attacks in history all originated from cross chain bridge vulnerabilities. Hemi Tunnels utilizes Bitcoin's proof of work to achieve faster final confirmation, reducing the typically one week confirmation time to a shorter and more secure window, thanks to the design of Hemi state anchoring to Bitcoin. The core innovation of this mechanism is that it does not rely on the traditional challenge period model. In Optimal Rollup, users need to wait for a 7-day challenge period to ensure asset safety. But Hemi Tunnels compresses this time window to the confirmation time of Bitcoin by directly anchoring Bitcoin PoW. From a security model perspective, the attack vector of Hemi Tunnels is much smaller than that of traditional cross chain bridges. Attackers cannot simply attack a smart contract to steal funds, but need to simultaneously attack the consensus mechanisms of both the Bitcoin network and the Hemi network. Hemi's challenger mechanism monitors and verifies the correctness of transactions and state proofs to ensure network integrity, adding an additional layer of security through monitoring and verifying transactions. The challenger mechanism draws inspiration from the design concept of Optimal Rollup, but has made significant improvements. In traditional OR systems, challengers need to pledge funds and bear the risk of being maliciously challenged. Hemi's challenger mechanism is more flexible, allowing anyone to run challenger nodes without the need for extensive staking. The advantage of this design is that it lowers the threshold for participation and increases the decentralization of the network. More challengers mean stronger security, as malicious behavior is easier to detect and prevent. The Hemi Bitcoin Kit unlocks the ability for smart contracts to access the state of Bitcoin. Developers can use the Hemi Bitcoin Kit to build native Bitcoin applications, such as staking, lending markets, and MEV markets, expanding the functionality of Bitcoin from a simple trading medium to a platform that supports complex DeFi operations. The technical implementation of Hemi Bitcoin Kit relies on a deep understanding of Bitcoin scripts. Although Bitcoin scripts are not Turing complete, they provide sufficient primitives to implement complex conditional logic. The Hemi Bitcoin Kit maps these primitives to smart contract interfaces, allowing EVM contracts to directly manipulate Bitcoin UTXO. The innovation of this design lies in the fact that it does not disrupt the native semantics of Bitcoin, but rather extends its functional boundaries through external smart contracts while maintaining Bitcoin script limitations. Finally, to summarize: Hemi processes transactions off chain and regularly embeds state snapshots into Bitcoin blocks through PoP, reducing the burden on Bitcoin and Ethereum. Off chain processing and Layer 2 design enable Hemi to handle higher transaction volumes. Hemi claims to support 50000 TPS and achieve 15ms final confirmation. However, the "15ms final confirmation" here refers to the confirmation time within the Hemi network, while the true Bitcoin final confirmation takes about 90 minutes. above.