A Post Quantum Migration Proposal

In an insightful discussion on the challenges of Bitcoin migration in the face of quantum computing threats, a novel dual-signature approach is proposed to mitigate the risks associated with the transition. The approach aims to address the limitations of forced migration by offering a more flexible and user-centric solution. By not setting a permanent loss deadline for users who miss initial migration windows, this method ensures that individuals still have the opportunity to move their funds by providing both traditional and quantum-resistant signatures.

The dual-signature strategy presents a phased security upgrade path. Initially, users can continue operating under the existing ECDSA framework, albeit with acknowledged quantum vulnerabilities. As a next step, they can opt for dual signatures, leveraging both ECDSA and quantum-resistant mechanisms, thereby marrying backward compatibility with enhanced security. The final aim is for users to fully transition to quantum-only signatures, moving away from ECDSA entirely. This gradual transition is designed to be driven by market forces rather than enforced by protocol deadlines, allowing for a more organic adoption process based on exchange requirements and user preferences.

A proposed implementation pathway for Bitcoin includes several phases, beginning with the enablement of quantum-resistant output types, followed by the introduction of dual-signature validation for new transactions. Subsequently, "transition transactions" would allow for the spending of UTXOs with exposed public keys through additional quantum proofs. The final phase involves increasing economic incentives for users to migrate to quantum resistance, such as fee discounts and priority processing, without imposing a hard cutoff date after which funds become permanently inaccessible.

This conversation underscores a critical reassessment of how Bitcoin addresses the quantum computing challenge, pivoting from a focus on eliminating migration problems to enhancing migration flexibility and safety. It contrasts the traditional forced migration approach, which prioritizes network security, with a dual-signature model that emphasizes user sovereignty and optional migration. The dialogue suggests exploring a hybrid strategy that combines elements of both approaches: employing a sunset policy for coins that are clearly abandoned, while offering dual-signature support for active but unmigrated funds. This nuanced perspective advocates for solutions that preserve user autonomy and choice, even in the face of increased implementation complexity, aligning with Bitcoin's ethos of decentralization and individual ownership.