Paradigm researcher Dan Robinson published a proposal called PACTs (Provable Address-Control Timestamps).
Robinson argues if quantum computing ever becomes a real threat to Bitcoin, the network may need to respond with an emergency soft fork that freezes spending from vulnerable addresses. Freezing vulnerable addresses would stop quantum attackers from draining wallets, but it would also lock out the legitimate owners.
PACTs would attempt to solve this by using zero-knowledge proofs to let holders secretly timestamp their knowledge of a private key. The timestamp is generated offchain and anonymously, without revealing address ownership or moving any funds. If a freeze ever happened, a holder who generated a PACT beforehand could use it to prove they knew the private key before any quantum computer could have derived it, separating them from an attacker.
Robinson says dormant Bitcoin addresses would be the most exposed under this scenario. Wallets belonging to early miners, long-term holders, and what he estimates as Satoshi Nakamoto's 1.1 million BTC haven't moved in years. Their owners may not be monitoring developments or in a position to upgrade.
He frames PACTs as a preparatory measure rather than a complete solution. From his paper: adopting PACTs now "would help give holders as much time as possible to secure their coins against an emergency sunset, while allowing us to leave the more difficult decisions, including whether a sunset is necessary or desirable, until later."
The catch: holders would need to generate a PACT before quantum computers arrive or before any emergency fork kicks in. Anyone who doesn't act in time would risk permanently losing access to their coins under this framework.
Robinson argues if quantum computing ever becomes a real threat to Bitcoin, the network may need to respond with an emergency soft fork that freezes spending from vulnerable addresses. Freezing vulnerable addresses would stop quantum attackers from draining wallets, but it would also lock out the legitimate owners.
PACTs would attempt to solve this by using zero-knowledge proofs to let holders secretly timestamp their knowledge of a private key. The timestamp is generated offchain and anonymously, without revealing address ownership or moving any funds. If a freeze ever happened, a holder who generated a PACT beforehand could use it to prove they knew the private key before any quantum computer could have derived it, separating them from an attacker.
Robinson says dormant Bitcoin addresses would be the most exposed under this scenario. Wallets belonging to early miners, long-term holders, and what he estimates as Satoshi Nakamoto's 1.1 million BTC haven't moved in years. Their owners may not be monitoring developments or in a position to upgrade.
He frames PACTs as a preparatory measure rather than a complete solution. From his paper: adopting PACTs now "would help give holders as much time as possible to secure their coins against an emergency sunset, while allowing us to leave the more difficult decisions, including whether a sunset is necessary or desirable, until later."
The catch: holders would need to generate a PACT before quantum computers arrive or before any emergency fork kicks in. Anyone who doesn't act in time would risk permanently losing access to their coins under this framework.
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