Hashed keys are actually fully quantum secure

The conversation between Antoine and Agustin on the Bitcoin Development Mailing List delves into the intricacies of enhancing security measures within the Bitcoin protocol. Antoine introduces a concept aimed at preventing attackers from exploiting old outputs by mandating that these can only be spent in conjunction with a QR output that is at least X blocks old and contains a specific commitment. This strategy is designed to eliminate the possibility of an attacker making premature commitments without access to the necessary private key, thereby securing the system against attempts to reverse deep chain alterations.

Furthermore, Antoine suggests that implementing this rule would likely necessitate upgrading the SegWit version, enabling developers to introduce modifications similar to the current Annex but potentially through varied approaches each with their distinct advantages and drawbacks. He acknowledges that while the finer details of these modifications are not immediately crucial, the possibility of their integration remains open.

Agustin, on his part, touches upon the procedural aspects of introducing these security enhancements. He concurs that a soft fork would be essential for deploying a QR signing algorithm, expressing optimism that such a change, aimed at safeguarding coins from irrevocable loss, would not stir controversy within the community. He outlines the technical requirements for the proposed changes, which include identifying inputs via secp256k1 verification and cross-referencing commitments among inputs while also verifying the depth of the spent inputs.

These exchanges underscore the ongoing efforts and discussions within the Bitcoin development community to fortify the cryptocurrency against vulnerabilities, emphasizing both the technical and procedural pathways to achieving enhanced security protocols.