Bitcoin bridging has long been a technical and philosophical challenge, while other blockchain networks have embraced interoperability with relative ease. This difficulty arises from Bitcoin’s intentionally strict consensus rules and limited scripting language, which makes crosschain transactions cumbersome despite the demand for decentralized bridges. Over the years, Bitcoin Virtual Machine (BitVM) protocols have been developed to address these limitations. Still, they come with trade-offs, including increased complexity and reduced decentralization.
Bitcoin Virtual Machine (BitVM) protocols are designed to enhance Bitcoin’s capabilities by addressing its scripting language limitations. These protocols aim to improve the network’s ability to execute complex computations required for crosschain transactions. However, this enhancement comes at a cost: increased complexity and reduced decentralization. This trade-off has led many to question whether these advancements are worth the potential risks.
In an exclusive interview with Cointelegraph, Sergio Lerner, a science specialist at RootstockLabs, discussed the limitations of past approaches and the potential of Bitcoin (BTC) bridging for the broader decentralized finance (DeFi) space. Related articles delve into topics such as Bitcoin’s scripting language, its limited computational capabilities, and the challenges posed by BitVM protocols.
Bitcoin’s scripting language, while reliable and secure, was not built to support the complex computations necessary for validating crosschain transactions. Bitcoin did not have a language expressive enough to support [decentralized bridges], which has historically limited efforts to build fully decentralized and trust-minimized bridges. While earlier approaches relied on trusted parties or external committees to monitor and validate disputes on the network, Lerner noted that these methods introduced new security assumptions and reduced Bitcoin’s decentralization.
Lerner emphasized that any system relying on trusted parties or external committees risks compromising security unless those parties act honestly. This is a significant limitation compared to two-party protocols based on BitVMX, such as payment channels, which do not require external committees for validation. In contrast, BitVM-based systems depend on at least one committee member acting honestly to maintain security.
BitVM protocols often depend on trusted parties or external committees to monitor and validate disputes on the network. This introduces new security assumptions and reduces Bitcoin’s decentralization. Lerner explained that a limitation of every BitVM protocol is that it needs covenants for Bitcoin, and without covenants, they must emulate them with a committee that co-signs a set of transactions. This requires at least one committee member to act honestly to maintain system security.
This limitation does not exist in two-party protocols based on BitVMX, such as payment channels, which do not require external committees for validation. Instead, these systems rely solely on the agreement between two parties to ensure security and functionality. Lerner highlighted that BitVMX is currently the cheapest and most resource-efficient disputable computing protocol for Bitcoin, making it a candidate for building validating bridges for the network.
Despite its challenges, Lerner emphasized that BitVMX offers an alternative method for Bitcoin bridging, enabling participation in broader blockchain applications. RootstockLabs science specialist Sergio Lerner stated that BitVMX is "currently the cheapest and most resource-efficient disputable computing protocol for Bitcoin," making it a promising option for building validating bridges on the network.
However, Lerner acknowledged the need for rigorous testing and careful deployment to avoid risks. He emphasized that any team rushing to deploy a BitVM-based system without proper testing runs the risk of compromising users’ funds. This caution underscores the importance of due diligence when adopting new technologies in the blockchain space.
In conclusion, while Bitcoin’s scripting language and limited computational capabilities have historically posed significant challenges for crosschain transactions, advancements like BitVMX offer promising solutions to these limitations. However, the trade-offs associated with these protocols—increased complexity, reduced decentralization, reliance on committees or external parties—pose questions about their feasibility and practicality in the broader context of decentralized finance (DeFi). As Bitcoin continues to evolve, its ability to bridge disparate blockchain networks will play a crucial role in unlocking its full potential as a global digital currency.
