GoKawiilResearchers find new method to forge RSA signatures without factoring keys
Cryptographer Nadia Heninger and colleagues have published research describing a novel technique that forges valid RSA digital signatures without first factoring the private key, a method previously assumed to be the only path to breaking RSA. The approach cuts the computational resources needed by orders of magnitude compared to earlier attacks, though it still requires far more computing power than most attackers could muster.
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Cryptography expert Karsten Nohl says the result, if confirmed through peer review, would be a conceptual breakthrough because it challenges the long-held assumption that breaking RSA signatures requires factoring large integers. The finding currently poses little practical risk to standard implementations, but it could push researchers to reassess RSA's theoretical security margins, especially for smaller key sizes like 1024-bit, and may accelerate scrutiny ahead of an eventual quantum-computing threat.
- A new attack forges RSA signatures without factoring the private key, a first in cryptography research.
- The method reduces computational cost by orders of magnitude versus prior factoring-based attacks, though it remains impractical for most attackers.
- Experts like Karsten Nohl call it a potential conceptual breakthrough pending peer review, while stressing no immediate real-world threat exists.
Source: arstechnica.com, 2026-09-24
Published there as: “There's a new way to break RSA that's faster than anything we've seen before”
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