Researchers from UC San Diego and the French Institute for Research in Computer Science demonstrated a method to forge RSA signatures without extracting private keys from hardware security modules. The findings were submitted to the IACR Cryptology ePrint Archive on September 20.
The attack involved disabling the FIPS mode of a hardware module to sign unformatted data. By requesting approximately 4 billion signatures using a test key, the team performed calculations to replicate the signing process without ever accessing the internal key directly.
The study focuses on the RSA scheme, which differs from the ECDSA algorithms used by Bitcoin and Ethereum. The authors noted that standard RSA implementations use padding that prevents this specific vulnerability, suggesting no immediate operational threat to most systems.
The researchers utilized a 1,024-bit key for their demonstration. They argue that this result serves as evidence for the necessity of transitioning away from RSA-based encryption toward post-quantum cryptographic standards.
While the team explored RSA vulnerabilities, separate research from Caltech suggests that 10,000 to 20,000 qubits could potentially threaten elliptic-curve signatures used in Bitcoin. Google has targeted 2029 for completing its own migration to post-quantum security.
