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Paradigm researcher Dan Robinson published a proposal on May 1 that could let dormant bitcoin holders, including wallets believed to be associated with Satoshi Nakamoto, silently prove address control before quantum computers become capable of cracking cryptographic keys.
The proposal, titled Provable Address-Control Timestamps (PACTs), describes a three-step method that uses existing Bitcoin tools to timestamp cryptographic proof of wallet ownership. Robinson said the approach requires no on-chain transaction and does not broadcast any public signal.
Under the method, a holder would store a secret salt, a BIP-322 message signature, and an OpenTimestamps proof file, then wait. The stored materials are intended to support a later “rescue” if Bitcoin adopts a quantum-related emergency mechanism.
Robinson framed PACTs as a hedge against a dilemma for Bitcoin if cryptographically relevant quantum computers (CRQCs) arrive before the protocol adapts. In that scenario, addresses with exposed public keys could become vulnerable to theft. If Bitcoin instead implements a sunset soft fork to freeze those addresses, dormant holders could be forced into a public coin migration.
For wallets believed to belong to Satoshi Nakamoto, a forced migration could also reveal whether the pseudonymous creator is alive, active, and still holding keys. Researchers estimate those wallets hold approximately 1.1 million BTC, worth more than $75 billion at current prices.
Robinson said PACTs would generate a 256-bit secret salt and use BIP-322 full message signing to prove control of a vulnerable scriptPubKey. The resulting commitment hash would then be timestamped using OpenTimestamps.
According to the proposal, OpenTimestamps batches hashes into a Merkle tree and embeds the root in a Bitcoin OP_RETURN output. Robinson described OpenTimestamps as a free, trustless Bitcoin-based timestamping service, noting that Bitcoin’s 2008 white paper positioned it as a distributed timestamp server.
Robinson said that if Bitcoin later implements a sunset soft fork, a PACT holder could submit a STARK zero-knowledge proof showing they knew the salt and control proof before a cutoff date established prior to CRQC capability. The rescue transaction would be bound to prevent replay, while the underlying keys and salt would remain hidden.
The proposal builds on draft BIP-361, which addresses quantum-vulnerable legacy addresses, and references earlier forum discussions by Jeremy Rubin on similar concepts.
Robinson acknowledged that the design is illustrative and would require review from cryptographers, Bitcoin developers, and the broader community.
He also highlighted practical limits: the proposal does not extend cleanly to multisig wallets, complex scripts, or custodial accounts, which would require additional standardization work.
Risks remain. Robinson said Bitcoin may never implement a quantum sunset, and even if it does, this specific rescue path may not be included. He advised holders not to rely solely on PACTs until a rescue protocol clears consensus. Still, he argued the cost of creating one is low enough to justify acting once a standard format is agreed upon.
After publication, Bitcoin developers and quantum researchers discussed the proposal on X, focusing on STARK integration timelines, the feasibility of a soft fork adding zero-knowledge proof verification, and whether the privacy protections would hold in practice.
Robinson said adopting a PACT standard now would give long-term holders maximum time to secure coins before any emergency fork, allowing harder decisions—such as whether a quantum sunset is warranted—to be addressed later.
He credited Eli Ben-Sasson, Jameson Lopp, Neha Narula, Nic Carter, and others in the acknowledgments.
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