Factoring \"short-sleeve\" RSA keys with polynomials
Summary
The Trail of Bits post reveals a polynomial-based attack that exploits specially formed RSA moduli with regular zero-bit patterns, enabling practical factoring of affected keys. It documents a real-world vulnerability in CompleteFTP caused by a mismatched RNG output, how the bug was reverse-engineered, the scope of impacted keys, and the mitigations added by the vendor. The article also discusses how this cryptanalytic approach could inform detection and defense for similar weak-key scenarios.