New Bitcoin Quantum Proposal Provides a Solution for Proving Control Without Transferring Funds

The concern of quantum computing has long been a challenge for Bitcoin, with a significant issue being the potential theft of millions of bitcoin stored in old wallets with exposed public keys. This includes the estimated 1.1 million bitcoin owned by the pseudonymous creator Satoshi Nakamoto, valued at around $84 billion. One possible solution is a soft fork that would phase out the use of legacy address types, forcing holders to move their funds to quantum-safe formats before attackers can access their private keys. However, this approach poses a problem for long-dormant holders like Satoshi, who would need to publicly reveal their presence or risk losing access to their assets. To address this issue, Dan Robinson from Paradigm has proposed a concept called Provable Address-Control Timestamps (PACTs), which enables holders to generate a proof of ownership without spending their coins. This proof can be timestamped and stored privately, allowing holders to reveal their ownership only when they need to spend their coins. The proposal involves generating a random salt and using a standard for signing messages from a Bitcoin address without spending from it. The salt and proof are then bundled together and timestamped through a free service called OpenTimestamps. If Bitcoin were to activate a soft fork that freezes quantum-vulnerable coins, the protocol could include a rescue path that accepts a zero-knowledge proof showing the holder created their commitment before quantum hardware existed. This approach addresses a specific gap in the existing proposal by including a rescue path for wallets derived through the deterministic key generation standard introduced in 2012. However, the proposal requires Bitcoin to adopt a verification protocol that remains secure against quantum computers, which would need a separate soft fork with broad community consensus. The verification infrastructure does not currently exist in Bitcoin and would require significant new development. Ultimately, the proposal provides a way to make the debate around the freeze proposal less binary, offering a potential solution that balances the need to protect against quantum theft with the need to respect dormant property rights.