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

The discussion revolves around the concept of implementing a quantum canary, specifically using a 192-bit curve as a tripwire in the Bitcoin consensus mechanism. Pieter Wuille explores various facets of this approach, noting its simplicity compared to a full tripwire system which might involve more complex dependencies and potentially disrupting consensus rules that align poorly with Bitcoin's core design principles. He mentions the idea of integrating a Zero-Knowledge Proof (ZKP) verifier within the Bitcoin consensus to validate proofs without necessitating additional complex implementations. However, he acknowledges the practical challenges and potential resistance from engineers concerning the integration of such specific, one-off consensus rules.

Further insights include a comparison of the security thresholds for secp192r1 and secp256k1 curves against quantum computing attacks, invoking data from a Google research paper on quantum computing's impact on cryptographic systems. According to the paper, breaking a 192-bit curve would require significantly fewer qubits than a 256-bit curve, suggesting a narrower security margin between these thresholds than previously anticipated. This implies that a quantum computer capable of breaking the secp192r1 might also soon after break the secp256k1, thereby questioning the effectiveness and timing of a 192-bit canary in signaling quantum threats.

Additionally, another programmer, conduition, critiques the necessity of linking the canary mechanism to other complex cryptographic processes like DLEQAG proofs or specific Bitcoin transactions. He suggests a more streamlined approach where breaking the secp192r1 curve alone could suffice to trigger a network-wide alert, proposing the publication of a simple cryptographic statement on-chain. This method would bypass the complications associated with broader consensus changes while still providing an early warning system against quantum advancements.

These exchanges underscore a broader debate within the Bitcoin development community about how best to anticipate and mitigate potential quantum threats without overcomplicating the existing blockchain infrastructure or prematurely alarming the network. The conversation highlights both technical and strategic considerations in enhancing Bitcoin’s quantum resilience. For further details, references to the discussed Google paper can be found here, and the QCAP thread is accessible here.