CoinDesk
Bitcoin Core developer Cory Fields has proposed a way for owners to trap future quantum attackers by putting their collateral at risk. In his example, an attempt to move 1 BTC from a vulnerable wallet would require another 1 BTC from a quantum-safe wallet, with both amounts locked for a waiting period such as 30 days.
Owners who prepared a hidden proof of ownership in advance could reveal it during that window, reclaim their bitcoin and take the attacker's collateral. Fields outlined the idea on the bitcoin-dev mailing list.
Why it matters
A sufficiently powerful quantum computer could derive a wallet's secret spending key from its public key. Some early Bitcoin payments exposed public keys, leaving their associated coins potentially vulnerable.
Fields' proposed traps offer an alternative to a debate over freezing vulnerable coins, which could also lock out owners who never upgraded. Attackers would not know which holdings were protected before putting up collateral.
The owner-claim mechanism would not protect lost coins. Fields also sketched an auction system for inactive holdings that would burn targeted coins and award an attacker's collateral to a winning bidder.
Market impact
The proposals are thought experiments, not implemented protections. They depend on quantum-safe wallets and enforcement rules that have yet to be written.
The collateral requirement would also apply to legitimate owners moving vulnerable bitcoin, because the blockchain could not distinguish them from attackers. A holder with 1 BTC in an old wallet would need matching funds under the example.
Frequently asked questions
-
How would a Bitcoin owner claim an attacker's collateral?
The owner would prepare hidden proof of ownership in advance and reveal it during the waiting period, reclaiming the bitcoin and taking the collateral.
-
How much collateral does Fields' example require?
Moving 1 BTC from a vulnerable wallet would require another 1 BTC from a quantum-safe wallet. Both amounts would be locked for a waiting period, such as 30 days.
-
Why are some early Bitcoin holdings potentially vulnerable?
Some early Bitcoin payments exposed public keys. A sufficiently powerful quantum computer could derive a wallet's secret spending key from its public key.
-
Would legitimate Bitcoin owners need to post collateral?
Yes. Under the proposed rules, legitimate holders moving vulnerable bitcoin would also need matching collateral because the blockchain could not distinguish them from attackers.
-
Are quantum landmines already protecting Bitcoin wallets?
No. Fields described the proposals as thought experiments that depend on quantum-safe wallets and enforcement rules that have yet to be written.
CryptoSlate
WuBlockchain
CoinTelegraph
WatcherGuru
TheBlock