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

A notable proposal involves a post-quantum commit/reveal scheme that leverages the Taproot mechanism to secure EC outputs from quantum computer (QC) attacks. This scheme allows users to create a QR output that commits to a hash of a pubkey within a Taproot leaf, which remains hidden until it's time for spending. The advantage of this approach is its efficiency and the lack of necessity for nodes to track a new commitment store, as commitments remain concealed within the Tapleaf until spend time. Importantly, this method enables pre-commitment to the pubkey hash well before transaction details are finalized, offering flexibility in transaction preparation without compromising on security.

Further insights into securing Bitcoin against QCs question the immediate need for such measures, considering the uncertain timeline for the development of QCs capable of breaking current cryptographic defenses. However, the consensus leans towards proactive steps to ensure Bitcoin's resilience against these theoretical advances. One idea floats a soft fork to introduce a post-quantum signature scheme while phasing out secp256k1 based outputs, balancing readiness for QC threats with the risks of premature obsolescence of current cryptographic standards.

A proposed commit/reveal scheme aims to protect against both known and unknown public keys under potential QC attack scenarios, suggesting a soft fork implementation for enhanced security. This strategy involves creating transactions that include a unique commitment to the transaction ID, which must be verified by nodes after a specific delay period to prevent preemptive attacks by QCs. Issues like reorgs, spam, and the handling of multisig and Lightning Network outputs present challenges but also areas for innovative solutions.

The dialogue also touches upon operational concerns, including the practicality of implementing OP_RETURN outputs to carry commitments and strategies to mitigate spam and system abuse. Discussion of multi-input transactions and future-proofing against evolving QC capabilities underscores the ongoing evolution of Bitcoin's security posture.

In summary, the conversation among Bitcoin developers highlights a nuanced understanding of the threats posed by quantum computing, proposing forward-looking solutions that balance immediate practicality with long-term security objectives. The integration of post-quantum cryptographic mechanisms through soft forks, and the exploration of commit/reveal schemes tailored to Bitcoin's unique transaction model, reflect a proactive approach to safeguarding the network against emerging technological challenges.