Pre-emptive commit/reveal for quantum-safe migration (poison-pill)

The discussion revolves around a proposed method to enhance the security of Bitcoin transactions against potential quantum computing threats through a soft fork, rather than opting for a hard fork. The proposal introduces a novel framework that mandates new rules for spending certain Unspent Transaction Outputs (UTXOs) post-activation at a specific block height. This mechanism includes a two-tier announcement system for UTXOs identified as vulnerable. Initially, a "weak announcement" can be made without needing the private key, merely signaling the intent to spend a UTXO after a certain number of blocks have passed. This is followed by a "strong announcement," which necessitates a commitment proof linking back to an earlier, pre-fork commitment, thereby providing evidence of the UTXO's inclusion in the blockchain.

The essence of this approach lies in its ability to maintain backward compatibility while adapting to new security measures. By allowing UTXOs to be spent only after adhering to the announcement protocols, it ensures that pre-signed transactions remain valid but introduces a delay in their execution. More importantly, this strategy empowers users who have made commitments before the fork to secure their transactions against quantum attacks effectively. The strong announcement, with its requirement for a commitment proof, enables these users to assert priority over others, including potential attackers, during the specified window.

This proposed soft fork distinguishes itself by not altering the fundamental nature of transactions but by modifying the conditions under which vulnerable UTXOs can be spent. It ensures that all nodes, irrespective of their update status, will recognize transactions as valid, albeit subject to the new timing rules. This method thus offers a sophisticated blend of enhancing security against quantum computing threats while ensuring the network remains cohesive and transactions from the past retain their validity and integrity.