Public key recovery for EC leaves in P2MR (BIP-360)

The discussion revolves around a modification in the Schnorr challenge where there's a suggestion to commit to H(Q) rather than Q itself, which would facilitate key recovery. This alteration appears to address concerns related to security and functionality within cryptographic systems.

In relation to Bitcoin's protocol enhancements, Pay to Witness Public Key Hash (P2WPKH) is noted for its security feature that protects against quantum attacks by not revealing an EC public key until a transaction is made. This characteristic stands in contrast to Taproot's approach, where similar protections are absent. However, the proposed Pay to Taproot Hash (P2TRH) aims to incorporate this beneficial attribute into Taproot, enhancing its security against potential quantum threats.

An innovative concept introduced is the "relative expiry for the key spend" on P2TRH coins. This idea entails disabling the key spend path after a coin has been held for a certain period, such as one year, making it only possible to execute transactions via the script path. This mechanism provides a preventive measure against quantum attacks by ensuring that even if a quantum computer could compromise the EC keys from the mempool, the coins would remain secure due to the expired EC path, allowing only the post-quantum secure script path to be used for transactions. This strategy offers a fallback that does not rely on an EC-disabling fork and adds an extra layer of security to the system.