Quantum computer breaks 15-bit elliptic curve cryptographic key

The Bitcoin community continues to debate whether cryptographically relevant quantum computers are imminent or decades away.

Project Eleven, a quantum security research company, awarded a prize to researcher Giancarlo Lelli for using a quantum computer to break a 15-bit elliptic-curve key — a small-scale version of the same cryptography used in Bitcoin, which relies on far larger 256-bit keys.

Lelli was able to derive a private key from the public key paired to it, using a “variant” of Shor’s algorithm, an integer factorization algorithm for quantum computers, according to Project 11’s announcement on Friday.

Bitcoin’s keys are 256 bits long, representing a “large” gap from the 15-bit key Lelli was able to crack, Project 11 said. However, the gap between Bitcoin’s 256-bit keys and the number of bits a quantum computer can factor has “fallen sharply” since 2025. Project 11 added.

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