Introduction
The opinions expressed in this piece represent solely the author and do not reflect the views of crypto.news’ editorial team.
Smart Contract Platforms and Fee Assets
In the landscape of smart contract platforms, each employs a fee asset integral to its operations—Ethereum uses ETH, while Solana relies on SOL. However, the situation becomes complicated when it comes to Bitcoin (BTC).
If developers seek expressive applications built on Bitcoin, they often find themselves entwined with the economic models of external networks. For instance, on the Stacks platform, transaction fees are paid in STX. Even EVM-compatible Bitcoin layers claim to use BTC as a gas token, yet they typically deploy their own native assets that follow EVM standards—including an 18-decimal representation—all while existing within a Layer 2 environment.
In stark contrast, Bitcoin boasts a well-functioning fee market driven by user bids for block space charged in sat/vB, enabling miners to prioritize transactions based on fee rates.
OpNet: A New Approach
This introduces an intriguing possibility: what if a smart contract interaction could utilize Bitcoin transactions for execution, allowing payments directly in BTC without the need for separate gas tokens, while ensuring that the smart contract remains verifiably connected to the Bitcoin network? Enter OpNet, a project exploring this very concept.
Bitcoin excels at valuing block space, but lacks a comprehensive execution environment capable of charging for complex computations. Its scripting language, Bitcoin Script, is intentionally limited—stateless and not Turing-complete—making it incapable of unbounded computations, thus ensuring predictable validation across all nodes.
This limitation often necessitates executing Bitcoin smart contracts on external systems designed to meter computation and maintain their own fee structures, as seen on platforms like Stacks which charges fees in STX. For many, this is far from ideal.
Innovative Solutions with OpNet
Therefore, a solution that allows users to remain within Bitcoin’s native fee market while executing contracts externally would be preferable. Recognizing the intentional constraints of Bitcoin Script leads to innovative solutions that anchor computations in Bitcoin’s existing financial frameworks.
By harnessing a dedicated virtual machine tailored for deterministic execution of smart contracts—while Bitcoin serves primarily for timestamping, ordering, and pricing transactions—OpNet proposes a robust system where contract logic is executed through a WebAssembly-oriented virtual machine (OP-VM).
Notably, OpNet’s architecture eschews the introduction of a new fee asset; Bitcoin remains as the gas currency, simply fulfilling its role as a settlement layer. The model devised by OpNet fosters a simulate-then-spend approach rather than traditional execution chain methods, culminating in Bitcoin transactions to finalize computation.
Key Aspects of OpNet’s Framework
A contract request initially gets processed in simulation mode through an OPNet node that runs the contract without affecting the Bitcoin network. If state changes are necessary, the result is then translated into a Bitcoin transaction, authenticated, and sent through the network.
Two critical aspects arise from this framework. While OpNet maintains its compute metering, it does so using satoshis, thus preventing the introduction of a separate fee economy. Consequently, users engage with applications using familiar Bitcoin mechanics, where transaction costs are competitive in a bidding process for block space, and fees are dictated in sat/vB.
Contract calls transform seamlessly into standard Bitcoin transactions, eliminating the need for users to navigate a new gas token ecosystem. Furthermore, this approach leverages established Bitcoin workflows, including UTXO handling, connecting with providers, and the integration of offline signing.
Conclusion
Smart contracts reside within a Wasm runtime, programmed in AssemblyScript, designed to provide Solidity-like functionality without suggesting a transformation of Bitcoin Script into a fully operational virtual machine. The prevailing view that BTC cannot operate as a gas token often hinges on the misconception that the Bitcoin base layer must measure computation directly.
In reality, Bitcoin’s utility lies in expediting block space and transacting value, with computation safely executed by an external machine. By processing every state-altering interaction through standardized Bitcoin transactions, fees are expressed in familiar metrics and controlled within satoshis, facilitated by parameters at the end-user level like feeRate and maximumAllowedSatToSpend.
With these innovations, the prospect of using BTC as a gas is not just an idea, but a workable solution. By keeping transaction fees BTC-native throughout the entire process, while maintaining a contract runtime based on WebAssembly, the logic remains robust and expressive, all without shifting the fee currency.
