PACTs: Timestamped Proofs for Recovering Quantum-Vulnerable Bitcoin
Summary
The document proposes Provable Address-Control Timestamps (PACTs) as a way for Bitcoin holders to preserve a possible route to spend from addresses that might later be disabled because quantum computers can derive their exposed public keys. The concern is that a sunset could force dormant holders to move coins publicly, while doing nothing could leave them vulnerable to theft. Existing deterministic-key rescue methods may not cover early addresses such as those attributed to Satoshi.
To create a PACT, a holder signs a standardized message proving control of an address, commits to that proof using a secret salt, and timestamps the opaque commitment through Bitcoin-based timestamping. If a future fork adopts PACT rescue rules, the holder could submit a post-quantum zero-knowledge proof that the commitment predates the threat, without revealing the original proof or when it was made. This is a design sketch, not a formal protocol; the document notes implementation is uncertain, and multisig, complex scripts, custodians, and hardware wallets need further standardization. The timestamping interaction may also expose network metadata, and holders must securely retain recovery artifacts.
Key ideas
- PACTs timestamp a salted commitment to proof of control without publishing an onchain transaction from the holder.
- A future protocol fork could accept a post-quantum zero-knowledge proof to rescue eligible sunsetted outputs.
- Timestamping may preserve options for early Bitcoin addresses that deterministic-key rescue methods cannot cover.
- PACTs do not guarantee recovery because Bitcoin may not adopt a sunset or the proposed rescue mechanism.
- Support for multisig and complex wallet arrangements requires additional design and standardization.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.