Factoring “short-sleeve” RSA keys with polynomials

Researchers discovered a class of weak RSA/DSA keys called "short-sleeve" keys whose biased limb bit patterns enable fast factoring by converting moduli into polynomials with small coefficients; one pattern was traced to a CompleteFTP key-generation bug in older .NET code that produced recoverable keys. The team recovered 603 RSA and 74 DSA private keys generated by vulnerable CompleteFTP versions, released detection and remediation tools, and described a polynomial-based cryptanalytic technique and guidance for identifying and mitigating affected keys.