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

The discussion on implementing a tripwire mechanism for disabling Elliptic Curve (EC) spending post-quantum transition delves into various technical considerations and alternatives to on-chain proof. The primary suggestion revolves around the use of the signature or discrete logarithm of the Nothing-Up-My-Sleeve (NUMS) point as a sufficient proof, eliminating the need for trustless rewards or on-chain inclusion solely for historical record. This approach allows validator nodes to disable EC spending based on the detection of NUMS signatures in any part of the network, such as transaction pools or peer-to-peer messages, which could potentially offer more flexibility and rapid response compared to traditional block confirmations.

There are concerns regarding the possible early activation of these mechanisms by miners, motivated by increased transaction fees, especially as block subsidies decrease and hardware investments remain unrecovered. It's suggested that nodes should have the capability to reject premature activations, which might be attempted in bad faith. The method to technically measure and enact majority hash power support for disabling actions is also questioned, with worries about the responsiveness and reliability of such measures over typical blockchain epochs.

Further, the email touches on the decision against introducing a hybrid EC and Post-Quantum (PQ) cryptographic signature scheme under the SHRINCS proposal, citing several reasons. These include the complexity and potential fragility of implementing a new Schnorr-based signature combination, minimal gains in efficiency, redundancy given the standalone deployment of SHRINCS for post-quantum operations, and security concerns that outweigh the benefits of hybridization. Instead, the focus remains on utilizing simpler, more isolated cryptographic paths that are deemed adequate for future security needs without the added risks and complications of a hybrid system.