Quantum Computer Cracks 15-bit ECC Key; Bitcoin's 256-bit Security Still Intact, but Post-Quantum Migration Clock Speeds Up

CryptoSlate reports that Project Eleven awarded researcher Giancarlo Lelli the QDay Prize on April 24 after he derived a 15-bit elliptic-curve private key from a public key using publicly available quantum hardware. The result is the largest public demonstration so far and marks a 512-fold leap from a 6-bit proof-of-concept shown in September 2025. Lelli used a Shor's algorithm variant adapted to the elliptic curve discrete logarithm problem (ECDLP), the mathematical backbone of Bitcoin's signature system, running on hardware with roughly 70 qubits. No existing quantum machine is capable of compromising real Bitcoin wallets. Bitcoin's 256-bit elliptic-curve security remains well beyond current quantum capabilities. Even so, timelines are moving up: on March 31, Google reduced its resource estimates for ECDLP256 and pointed to post-quantum cryptography migration targets after 2029. Cloudflare soon echoed that stance, while the UK's National Cyber Security Centre (NCSC) has set migration milestones spanning 2028 to 2035. On-chain data suggests about 6.93 million BTC could be exposed to future quantum threats because their public keys are already visible. Within the Bitcoin community, proposals BIP 360 and BIP 361 aim to accelerate adoption of quantum-resistant output types. The hardest part remains execution—coordinating a network-wide transition in a decentralized system.