Paradigm Unveils PACTs Proposal for Bitcoin’s Quantum Future
On May 1, Dan Robinson, a general partner at Paradigm Bitcoin, introduced a proposal for Provable Address-Control Timestamps (PACTs). This innovative system allows inactive Bitcoin holders to privately timestamp proof of key ownership before quantum computers emerge, potentially safeguarding Satoshi Nakamoto’s estimated 1.1 million BTC.
Summary
- PACTs operate in three phases: utilizing a secret salt, a BIP-322 ownership proof, and an OpenTimestamps commitment anchored on-chain, all while avoiding any public on-chain transactions.
- Should Bitcoin later deploy a quantum sunset soft fork, PACT holders can present a STARK zero-knowledge proof to recover their coins while keeping their keys confidential.
- Robinson stated that if Satoshi had to reveal keys during any mandated migration, it would mean “telling the world that they are alive and still in possession of their keys.”
Robinson introduced PACTs as a safeguard against what he refers to as the Satoshi Problem within the conversation around Bitcoin’s quantum threats. The official Paradigm post elaborated on the issue: if quantum computers emerge before Bitcoin adapts, historic addresses with exposed public keys could be vulnerable to theft.
If Bitcoin hastily implements a sunset soft fork to secure those addresses, inactive holders may face a forced and public migration of their coins. PACTs present a third option, allowing holders to silently timestamp proof of ownership in 2026, postponing any further action until a rescue mechanism is formalized.
As reported by crypto.news, around 1.7 million BTC are still held in address types that are exposed to quantum threats, including wallets linked to Satoshi, collectively valued at approximately $75 billion.
The proposal is built upon BIP-361, penned by Casa CSO Jameson Lopp, which outlines a gradual transition away from legacy signatures, post which unmigrated coins would be locked.
Bitcoin.com highlighted that Robinson pointed out the need for additional standardization in areas like multisig, complex scripts, and hardware wallet support, suggesting that Bitcoin may never adopt a quantum sunset.
As documented by crypto.news, discussions around Bitcoin’s quantum vulnerabilities have heated up in 2026, especially after Blockstream CEO Adam Back advocated for optional quantum-resistant upgrades at Paris Blockchain Week, opposing the forced wallet freezes presented in the BIP-361 approach that PACTs are intended to support.
Additionally, as noted by crypto.news, Naoris Protocol CEO David Carvalho raised concerns that dormant wallets, including Satoshi’s, would become “ripe for the picking” once quantum computers achieve adequate capability, warning that a quantum attack on Bitcoin could significantly undermine trust in the asset.