Post-Quantum commit / reveal Fawkescoin variant as a soft fork

The discourse delves into the intricacies of enhancing Bitcoin's Taproot mechanism with quantum-resistant (QR) features, focusing on a method where an output commits to the hash of a public key within a Taproot leaf. This commitment is concealed until it is revealed at the time of spending. A notable condition for spending these outputs is that they must be included in a transaction alongside a legacy Elliptic Curve (EC) output, with the requirement that the QR output has aged a minimum number of blocks. The dialogue underscores a potential vulnerability associated with commitments that only tie to a public key without including the transaction details. Such a scenario could allow attackers to duplicate the commitment, compromising its uniqueness and security.

Further examination reveals a nuanced suggestion to mitigate this issue by embedding a QR or Post-Quantum Cryptography (PQC) signing scheme within the Taproot leaf, thereby invalidating keypath spending and leveraging the hash function's resistance to quantum attacks. The conversation explores the concept of "taproot2," an idea that maintains structural similarity to the original Taproot but employs a PQC scheme instead of the standard BIP340 protocol, which could offer enhanced security against quantum threats.

A critical aspect of the proposed solution is the hidden nature of the commitment. It's emphasized that the true advantage lies not in the obscurity of the commitment act but in the concealment of the specific commitment value, which safeguards against quantum computational attacks aimed at uncovering the secret values within the commitment. The discussion acknowledges the challenge of implementing a PQC scheme from the outset but recognizes the necessity of such an approach to ensure future-proof security against evolving quantum threats. The dialogue concludes with a reflection on the practical feasibility of enumerating the UTXO set to verify the integrity of addresses against potential quantum-enabled adversaries, highlighting the ongoing efforts to fortify Bitcoin against such futuristic challenges.

This exchange sheds light on the complexities and considerations involved in evolving Bitcoin's security mechanisms to withstand quantum computing advances, illustrating the community's proactive stance on addressing potential vulnerabilities through innovative cryptographic solutions.