A Post Quantum Migration Proposal

The discussion revolves around the proposal regarding Bitcoin's security in the face of potential quantum computing threats. The concern primarily focuses on how to protect bitcoins that are vulnerable to quantum attacks, especially those in dormant addresses which are speculated to be largely lost due to various reasons such as deceased owners. The suggestion to delay the implementation of phase B is highlighted, emphasizing the need for flexibility in time horizons to accommodate unforeseen advancements or delays in quantum computing technology. This approach aims to afford users ample time to upgrade their security measures against quantum vulnerabilities.

Commit/reveal protocols emerge as a possible solution for safeguarding quantum-vulnerable funds. However, these protocols face significant challenges in practical application. They are difficult to communicate to the average user and are only applicable to addresses whose public keys have not been previously exposed. This limitation complicates their implementation, rendering them an impractical choice for securing a broad range of existing unspent transaction outputs (UTXOs), including all Pay-to-Taproot (P2TR) UTXOs. Consequently, despite their potential, commit/reveal protocols are deemed not worth the engineering and research efforts required for their adoption due to these constraints.

A notable aspect of the discussion is the technical consideration of implementing phase C, which involves unlocking funds through zk-STARK proof without necessitating a hard fork—a process typically associated with major updates or changes in blockchain protocols. This can be achieved by integrating phases B and C into a single upgrade, thereby maintaining continuity in consensus rules regarding the spending of pre-quantum addresses. Such a unified approach ensures that there is no interval during which users with mnemonic-seed wallets would be unable to access their funds, thus obviating the need for any hard forks. This method underscores a strategic pathway to enhance Bitcoin's resilience against quantum threats while minimizing disruption to its operational framework.