The path to general computation on Bitcoin (with OP_CAT)

The discussion about Bitcoin scripts and their statefulness, along with the potential for incorporating more complex functionalities such as covenants, presents a nuanced view of how Bitcoin might evolve to handle these advanced features. The email highlights that while Bitcoin scripts are fundamentally not stateful, achieving a semblance of statefulness is possible through the use of indexers and trackers. This approach would necessitate significant changes in how Bitcoin nodes operate, particularly regarding the storage and management of state information.

A key point raised concerns the implementation of OP_CAT and its implications for Bitcoin's security and functionality. The sender expresses concern over the potential dangers of allowing recursive covenants through OP_CAT, which could introduce complexities and vulnerabilities into the system. The concept of covenants, as defined by Peter Todd, involves restrictions on how a transaction output can be spent, ensuring that transactions conform to pre-defined rules. This mechanism enables stateful computation over Unspent Transaction Outputs (UTXOs), leveraging Bitcoin script operations to facilitate transitions between states (Peter Todd's covenant-dependent layer 2 review).

Furthermore, the email questions the motivation behind discussing smart contracts (SCs) within the Bitcoin ecosystem, especially given the sender’s involvement with Starknet, which already handles a significant value and offers a platform for SCs. The skepticism extends to what appears to be a promotional push for OP_CAT, suggesting that the consensus among developers regarding its adoption remains uncertain. The mention of OP_CTV introduces another layer to the conversation, hinting at its potential to unlock new use cases without the risks associated with recursive covenants. The sender seems to caution against hastily integrating stark proofs onto Bitcoin, pointing out the risks involved.

In conclusion, the email encapsulates a critical perspective on the ongoing debate around the introduction of stateful scripts and covenants in Bitcoin. It underscores the technical challenges, security concerns, and the broader implications of such advancements on the ecosystem. While acknowledging the potential for innovation, the sender remains cautious about the direction of these developments and their impact on Bitcoin's foundational principles.