Hashed keys are actually fully quantum secure

In addressing the complexities of ensuring cryptographic security in a post-quantum era, the discussion revolves around innovative methods for securing transactions on the Bitcoin blockchain against potential quantum computing threats. The initial proposal highlighted the concept of using elliptic curve (EC) signatures on static messages as a form of commitment within a quantum-resistant address framework. This approach was suggested to safeguard transactions by committing to a hashed signature of a static message, thus leveraging the inherent security of EC cryptography while preparing for quantum computational capabilities.

However, an alternative and simpler method was proposed, focusing on committing to public keys rather than signatures. This strategic shift is aimed at minimizing vulnerabilities that could be exploited by quantum computers. The essence of this strategy lies in the concealment of commitments until the moment of transaction revelation, which is crucial in any commit/reveal scheme. This preventive measure is essential to counteract the potential of quantum computing attackers, who could otherwise exploit exposed commitments to undermine the security of transactions.

The technical discourse further explores the implementation mechanics, suggesting the possibility of integrating a mechanism akin to Taproot. This would allow for commitments to be discreetly embedded within a quantum-resistant (QR) output script or alternatively, wrapped in a Pay-to-Script-Hash (P2SH) structure that employs a hypothetical quantum-resistant checksig opcode. Such methodologies are envisioned to encapsulate committed data within an 'inscription-like envelope' that remains sealed until the reveal transaction is executed.

To enhance the scalability of this security framework, the conversation suggests the adoption of accumulators. This approach would enable a single QR output to verify ownership of multiple legacy addresses through a commitment to a collective hash or a Merkle tree root of public keys. This method significantly increases efficiency by reducing the necessity for individual QR Unspent Transaction Outputs (UTXOs) for each locked Elliptic Curve (EC) UTXO, thereby streamlining the process of rescuing multiple locked EC outputs with a singular QR output.

This dialogue, forming part of the wider Bitcoin Development Mailing List discussions, underscores the ongoing efforts among developers to fortify the Bitcoin network against the burgeoning threat posed by quantum computing advancements. Through collaborative innovation, these strategies aim to preemptively secure the blockchain ecosystem, ensuring its resilience in the face of evolving computational challenges.