Quantum computer recovers 15-bit elliptic curve private key

A research team used a quantum processor to recover a 15-bit elliptic curve private key in a laboratory proof-of-concept run. The team prepared an ECC key with a 15-bit private exponent and executed a quantum routine designed to solve the elliptic curve discrete logarithm problem. Measurement results were processed classically to produce a candidate private key, which matched the public key in the test instance.

The experiment used quantum subroutines related to Shor’s algorithm and ran on current noisy intermediate-scale quantum hardware. The 15-bit instance required far fewer qubits and gate operations than real-world keys would need.

Modern elliptic curve deployments typically use key sizes of 256 bits or larger. Scaling a quantum attack from a 15-bit key to production-strength keys would require many more qubits, substantially lower error rates, effective quantum error correction and longer coherence times. Those capabilities are not available in current error-prone quantum devices.

Standards organizations, including the U.S. National Institute of Standards and Technology, have been working on post-quantum cryptography standards and guidance. Proposed replacements include lattice-based and code-based algorithms. Researchers run scaled-down quantum demonstrations to test algorithms and hardware and to inform migration planning for cryptographic systems.