Public quantum computer cracks 15-bit elliptic curve key, wins 1 BTC bounty

Independent researcher Giancarlo Lelli used a publicly accessible quantum computer to derive a 15-bit elliptic-curve private key, in what Project Eleven calls the largest quantum attack on elliptic-curve cryptography to date; Lelli was awarded a 1 BTC bounty under Project Eleven's Q-Day program. The result, while noteworthy, operates far below the 256-bit security used by Bitcoin and shouldn't be considered a threat to real-world crypto yet. It follows a 6-bit break demonstrated in 2025 by Steve Tippeconnic on IBM's 133-qubit quantum computer, which Project Eleven says Lelli's 15-bit result expands by a factor of 512. Project Eleven argues the gap from 15-bit to 256-bit keys is shrinking as an engineering challenge, while security experts remain divided on how quickly quantum hardware could scale. The article also notes about 6.9 million bitcoin wallets have visible on-chain public keys, highlighting urgency for migration to post-quantum cryptography.