Paradigm Researcher Proposes Quantum-Resistant Bitcoin Protection Method

Paradigm’s Quantum Protection Proposal

Dan Robinson, a researcher at Paradigm, has outlined a new model designed to protect dormant bitcoins, including those potentially belonging to Bitcoin’s creator Satoshi Nakamoto, from future quantum computing threats. The proposal introduces “Provable Address-Control Timestamps” (PACTs), a mechanism that would allow Bitcoin holders to prove they controlled a wallet before quantum computing advances to the point of deriving private keys.

How PACTs Work

The PACTs model leverages a timestamping system already embedded in blockchain functionality. Holders would generate a proof demonstrating control of their Bitcoin and timestamp it on the blockchain, creating an ownership record that could protect against future quantum attacks. This proof could later be unlocked, allowing users to reclaim their funds on a quantum-resistant version of Bitcoin.

According to Robinson, “This does not require Bitcoin to decide today whether a sunset is necessary,” and the approach gives users a way to prepare early, letting them “plant a seed now” in case protections are needed later.

Comparison with Alternative Proposals

Other quantum-resistance proposals exist, such as BIP-361 proposed by Casa’s chief security officer Jameson Lopp and other researchers. These alternatives typically establish a multi-year migration window for wallets, exchanges, and custodians to upgrade to quantum-resistant technology before “sunsetting” legacy signatures. After this period, any coins that failed to migrate would become unspendable.

However, this approach creates a distinct problem for dormant holders: moving funds would reveal that the owner is still active and could potentially link the wallet to others they control. The PACTs model aims to circumvent this dilemma by allowing users to prove ownership without broadcasting it on-chain.

Quantum Computing Threat Context

As quantum computing advances, crypto users and developers must plan defenses in parallel. According to Lopp and other BIP-361 researchers, more than one-third of all bitcoins in circulation could be exposed to quantum attacks due to visible public keys.

Real-world demonstrations are beginning to show incremental progress. An independent researcher recently derived a 15-bit elliptic curve key using quantum hardware, described as the largest such attack to date, though Bitcoin relies on stronger 256-bit encryption.

Timelines for “Q-Day”—when quantum computers can break modern cryptography—vary widely. Google researchers recently suggested a transition to post-quantum cryptography could be needed by around 2029, while others estimate practical attacks may still be years or decades away.

FAQ

What are Provable Address-Control Timestamps (PACTs)? PACTs are a mechanism that allows Bitcoin holders to generate and timestamp a proof of wallet control on the blockchain. This creates a record of ownership that could be used to recover funds on a quantum-resistant version of Bitcoin in the event of a future quantum threat, without requiring the holder to move their coins immediately.

How do PACTs differ from BIP-361? BIP-361 proposes a multi-year migration window during which users must move their coins to quantum-resistant addresses, after which legacy signatures would be “sunset.” PACTs, by contrast, allow users to prove ownership without broadcasting it on-chain, avoiding the privacy risk of revealing dormant holders are still active and potentially linking wallets together.

When might quantum computers threaten Bitcoin? Timelines vary. Google researchers suggested a transition to post-quantum cryptography could be needed by around 2029, though other experts estimate practical quantum attacks on Bitcoin may still be years or decades away. Bitcoin currently uses 256-bit encryption, which is significantly stronger than the 15-bit keys recently broken in laboratory demonstrations.