finance
Researcher Cracks 15-Bit Key on Quantum Hardware, 512 Times Larger Than Prior Record
An independent researcher used public quantum hardware to break a 15-bit elliptic curve key, winning a one-bitcoin prize and marking the largest such demonstration. This development underscores risks to bitcoin's cryptography, with 6.9 million coins exposed to potential future quantum attacks. Bitcoin lags Ethereum in preparing quantum-resistant upgrades, according to recent analyses.
Apr 25, 6:00 AM·3m read1 source
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Independent researcher Giancarlo Lelli broke a 15-bit elliptic curve key on publicly accessible quantum hardware, 512 times larger than the previous public demonstration in September 2025. Lelli won Project Eleven’s one bitcoin Q-Day Prize for the feat.
CoinDesk reported that while this is far from threatening bitcoin’s 256-bit elliptic curve security, it highlights advancing quantum capabilities relevant to cryptocurrencies.
Google's paper this month showed a quantum attack could be run with far fewer resources than previously estimated, in a window that races against bitcoin's own block times. The paper indicated that such attacks could break the cryptography protecting bitcoin wallet ownership.
Quantum computers cannot disrupt bitcoin mining or the blockchain ledger itself, but they could eventually break the cryptography that protects bitcoin wallet ownership.
9 million bitcoin, about one-third of everything ever mined, sits in wallets whose public keys are already permanently visible onchain. This includes Satoshi Nakamoto’s early holdings and any coins spent from since 2021’s Taproot upgrade, which are exposed to future quantum attacks because their public keys are visible on-chain.
Satoshi Nakamoto holds roughly 1 million bitcoin, untouched since the network's early days, in the exposed category.
9 million exposed bitcoin is from the network's first years, stored in an address format that published the public key by default. Any bitcoin wallet that has ever been spent from reveals the key for whatever remains. The 2021 Taproot upgrade activated and expanded the exposure problem by publishing the key protecting remaining bitcoin when spent since activation.
