# Fields' Bitcoin Proposal Would Require Equal Collateral for Vulnerable Coins

By Simon Yoon

Canonical URL: https://www.tokenpost.com/news/technology/51086
Published: 2026-11-07T20:55:06.000Z
Updated: 2026-11-07T20:55:06.000Z
Section: Technology

> The thought experiment would lock vulnerable coins and an equal BTC deposit for a waiting period of up to 30 days, including when owners make legitimate transfers.

Bitcoin Core developer Cory Fields has sketched a way to deter future quantum attacks on older Bitcoin holdings: anyone attempting to move coins from a vulnerable wallet would first lock an equal amount of BTC as collateral. The proposed mechanism would also apply to legitimate owners, who could face the same cost when making a transfer.

A sufficiently powerful quantum computer could derive the private key needed to spend coins from a public key. Some early Bitcoin payment formats exposed public keys on-chain, potentially putting coins held in those wallets at risk if that kind of attack becomes viable.

In Fields' example, an attempt to take 1 BTC would require the attacker to put up another 1 BTC from a post-quantum-safe wallet. Both amounts would then be locked for a waiting period, such as 30 days. Before quantum attacks became viable, the original owner could establish a separate post-quantum proof of ownership.

If an attacker tried to move the vulnerable coins, the owner could present that proof during the waiting period, reclaim the original BTC and take the attacker's collateral. The proof would give the owner a way to demonstrate control without relying on the key an attacker might derive from the exposed public key.

The proposed mechanism would not distinguish a thief from a legitimate owner. Someone moving their own 1 BTC would also need to lock another 1 BTC, under the example's terms. Owners without spare BTC could therefore be unable to move funds from older wallets, even if they still control them.

Fields also outlined a separate idea for coins presumed lost, including holdings attributed to Satoshi Nakamoto. Participants would place sealed bids tied to a vulnerable wallet. If someone tried to steal its coins, a smart contract associated with the winning bid would destroy the targeted coins and award the attacker's locked collateral to the winner.

Fields described both mechanisms as thought experiments. They depend on post-quantum-safe wallets being available, and he has not settled how the rules would be enforced.