Giving teeth to expected EC disabling: P2XX(-T)(-ML)

The discussion revolves around the challenges and strategies associated with safeguarding Bitcoin against potential quantum computing (QC) threats. Pieter Wuille highlights a significant observation regarding the incentives for QC investors, pointing out that there is little reason to believe a quantum computer would be developed to break 192-bit curves without also targeting 256-bit curves. This is particularly relevant considering the substantial investment likely required for such technology and the probable reactions from the Bitcoin network to enhance security measures in response to any threat.

Wuille critiques the practicality of using smaller order curves as a defense mechanism. While the idea of using algebraically similar curves with subgroups was considered, it seems insufficient on multiple fronts. However, the concept of canaries—specifically those utilizing Nothing-Up-My-Sleeve (NUMS) points on a sequence of increasing curve sizes—is still deemed worthy of attention. The method involves checking specific transaction outputs for cryptographic evidence, which miners might be disincentivized to censor due to the loss of transaction fee revenue. This approach, detailed in an academic paper, offers a potentially valuable but limited alteration to how block validations are processed, suggesting modifications to the sigops budget might accommodate this extra computation.

Further discussions address the dynamics of consensus changes within the Bitcoin mining community, emphasizing the complexities when miners have the power to censor updates. The activation of such security measures appears dependent on individual miners' decisions, thereby posing risks of slow implementation or non-adoption by bad actors once proofs of QC capability become public.

Lastly, considerations extend to the handling of cryptographic proofs, particularly the risks associated with revealing discrete logarithm problems (DLP). The suggestion leans towards maximizing input variety for hash functions and combining results to secure the network further. This conservative stance aims to mitigate unintended consequences, likening the exposure of certain cryptographic processes to handling "toxic waste," where utmost caution is necessary to prevent widespread security vulnerabilities across the Bitcoin ecosystem.