How to Understand AVM: A Turing-Complete Virtual Machine That Enables BTC to Achieve Dynamic "State Machines"?
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How to Understand AVM: A Turing-Complete Virtual Machine That Enables BTC to Achieve Dynamic "State Machines"?
AVM is a beneficial proactive exploration based on the expansion of BTC mainnet Script, capable of enabling some relatively simple smart contracts to be deployed on the Bitcoin mainnet.
Navigating Web3 tides with focused insightsAuthor: Haotian
How to understand the newly released AVM Virtual Machine whitepaper by @atomicalsxyz? Simply put: it simulates a Bitcoin virtual machine to enable the originally "stateless" Bitcoin mainnet to support smart contract systems, thereby achieving state recording and processing capabilities for more complex assets beyond BTC—similar to Turing-complete smart contracts. Here’s my take:
1) Bitcoin was originally designed as a peer-to-peer electronic cash system with limited Script data storage capability, basic OP Codes, and a verification logic for assets based on UTXO time locks and spending conditions.
Thus, the Bitcoin network can manage BTC assets in a "stateless" manner. Due to the constraints of the minimal UTXO model and predefined state transition rules, this stateless model can only handle limited management of the single BTC asset.
To introduce new assets on the Bitcoin network—such as BRC20, ARC20, or Runes—a more sophisticated dynamic "state machine" model is required to record asset storage, transactions, and state changes. How can this be achieved?
One approach is using external protocols and Layer-2 solutions to build the "state machine" off-chain, such as excellent scaling solutions like @NervosNetwork and @RoochNetwork, or native solutions like RGB and Lightning Network.
Another method involves directly extending Script functionality by adding new opcodes or storage space to handle creation and transfer of complex assets—approaches relying on BIP proposals such as Covenant and OP_CAT fall into this category.
These two methods are either too "active," making consensus difficult to achieve quickly, or too "passive," carrying significant uncertainty. The AVM Virtual Machine presents a special solution that lies between them—building a virtual machine execution environment directly on the Bitcoin mainnet.
2) How does it work? The AVM's core mechanism consists of three parts:
1. Bitcoin script simulation—essentially the Bitcoin instruction set—which achieves Turing-completeness via a dual-stack PDA (pushdown automaton);
2. Sandbox execution environment—the entire simulator runs in a controlled, isolated environment so that execution inside and outside the sandbox do not interfere with each other;
3. State hashing—enables participants to verify whether their indexer states are correctly synchronized, preventing potential attacks due to state inconsistency.
In simple terms: AVM leverages Bitcoin’s limited storage space and OP Code processing framework by introducing a special encoding and decoding method (a sandbox environment) within each Bitcoin mainnet transaction.
This sandbox comes equipped with its own indexer, sandbox parser (instruction set), global database, etc., capable of independently managing full-cycle asset storage and transaction state recording—effectively embedding a dynamic "state machine" within the BTC mainnet, enabling complex smart contract processing, state synchronization, and verification.
3) With AVM, the Bitcoin mainnet theoretically gains basic smart contract functionality, opening possibilities for Bitcoin to manage multiple complex assets and support DApps with intricate state logic—equivalent to giving the Bitcoin network some self-contained ecosystem-building capability.
This is undoubtedly a significant advancement—on par with innovations like RGB, Lightning Network, and other excellent Layer-2 protocol solutions in terms of BTC scalability. It may even surpass other approaches in native integration.
However, AVM relies on Bitcoin Script for encoding/storage and OP Codes for transaction execution, meaning it is constrained by Bitcoin’s mainnet performance—such as block size limits and block interval times.
Imagine a DeFi project built on AVM that can process only seven transactions per minute, with ten-minute waits between state transitions—even if theoretically sound, such smart contracts remain severely constrained. Moreover, developing complex contracts using Bitcoin Script instruction sets is far more complicated and challenging than writing smart contracts in Ethereum’s Solidity or similar languages.
Furthermore, the AVM whitepaper merely outlines a coherent internal virtual machine execution model; how it will actually deploy, operate, and maintain stability in real-world applications remains unknown.
In summary,
Overall, I view AVM's development and implementation as a valuable proactive exploration based on BTC mainnet Script extension. It could indeed facilitate the deployment of relatively simple smart contracts on the Bitcoin mainnet and enhance Bitcoin’s role and value in both Layer-2 ecosystems and hybrid on-chain/off-chain architectures like BitVM.
Yet, like all other BTC scaling solutions, AVM has its trade-offs. Its legitimacy and appeal will ultimately depend on post-launch ecosystem growth. A rational, cautiously optimistic stance is recommended.
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Haotian | CryptoInsight
