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

Sergio Demian Lerner and Boris Nagaev have engaged in a discussion about innovations in post-quantum commit/reveal schemes with a focus on enhancing Bitcoin's security against quantum computing threats. Lerner's proposal introduces a novel approach where a user generates a QR output that commits to a hash of a public key inside a Taproot leaf, which remains concealed until it is revealed at the time of spending. This innovative method allows for the commitment to be made well in advance of the transaction without revealing the transaction ID, thereby offering users greater flexibility in managing their transactions.

One of the standout features of Lerner's scheme is its efficiency and simplicity, as it eliminates the need for nodes to maintain a separate commitment store. This is possible because the commitment is hidden within a Tapleaf until it is spent, ensuring that it remains invisible to both observers and potential attackers. The requirement that the QR output must be a certain number of blocks old before spending leverages existing Bitcoin Core functionalities that track coin age, thus aligning with current consensus rules without necessitating additional storage or validation mechanisms.

Moreover, Lerner's approach promotes a more efficient utilization of block space. By allowing multiple Elliptic Curve (EC) coins to be spent together with a single QR output that holds EC public key commitments in Taproot leaves, it significantly reduces the blockchain space required for such transactions. If EC coins originate from the same address and therefore share the same EC public key, they can reuse the same commitment, further optimizing the process.

The conversation between Lerner and Nagaev reflects ongoing efforts within the Bitcoin development community to prepare for the advent of quantum computing. Through the exploration of such post-quantum cryptographic methods, developers aim to safeguard Bitcoin's security and integrity in the face of potential future challenges. The detailed discussion can be followed through the provided link, offering insights into the technical nuances and potential advantages of Lerner's proposed scheme.