A Post Quantum Migration Proposal

The discussion revolves around an innovative proposal to address the vulnerabilities of certain coins in the face of potential quantum computing threats. The idea involves temporarily locking these vulnerable coins during what is referred to as phase B, with a plan to make them spendable again at a future block height X, projected to be 5-10 years later. This strategy would provide additional time to refine the zk-STARK proof system intended for phase C, while still offering protection against a quantum computing breach, especially for those who may delay their protective actions. The flexibility of this plan also allows for the possibility of merging phases B and C into a single deployment should the development of phase C outpace the advancement of quantum computing or if quantum progress lags behind expectations.

A significant aspect of the proposal is its approach to handling transactions to and from vulnerable addresses. Instead of permanently blocking these transactions, which could result in confiscatory outcomes such as the loss of funds due to pre-signed transactions like Lightning force-closes being rendered invalid, the suggestion is to implement temporary restrictions. This change aims to leave open the possibility for future recovery schemes without necessitating a hard fork, thus avoiding permanent loss of access to funds for legitimate owners and mitigating potential ethical concerns associated with permanent blocks.

The conversation also touches on the ethical implications of this strategy, highlighting the dilemma faced by individuals unable to move their funds before the implementation of these changes, such as young heirs with time-locked inheritances. The debate underscores the challenge of balancing the risk of loss due to quantum attacks against the temporary inconvenience and uncertainty brought about by the proposed restrictions.

Furthermore, the email addresses technical considerations related to P2QRH (Pay to Quantum Resistant Hash) addresses and their interaction with the proposed phases. There's a query about whether phase B's restrictions on Elliptical Curve (EC) spending would extend to P2QRH Unspent Transaction Outputs (UTXOs), potentially leading to funds being locked until phase C if users mistakenly send money to P2QRH addresses requiring EC signatures. The discussion suggests that restricting all EC spending across script types during phase B could simplify the transition, ensuring that users can reclaim their Bitcoin once phase C is initiated. To facilitate this, the standardization of P2QRH address derivation and the strong recommendation against creating P2QRH addresses without a post-quantum spending path are advised. The proposal includes a technical solution wherein any EC check signature operation would fail unless preceded by a Post-Quantum (PQ) check signature operation within the same script, leveraging a flexible hybrid signature scheme to enable secure transactions under the new system.