Factoring Legacy RSA Public Keys of a 1990s Certificate Authority
Researcher M. Pherrin has successfully executed the factorization of the RSA public keys belonging to a legacy Certificate Authority (CA) operating in the 1990s. By utilizing the General Number Field Sieve (GNFS) algorithm—likely via the CADO-NFS implementation—the researcher recovered the private prime factors (p, q) from the CA's public modulus (n). This achievement demonstrates that legacy RSA bit-lengths, previously considered computationally secure, are now susceptible to modern distributed computing resources. The successful factorization highlights a critical risk in Public Key Infrastructure (PKI) environments where antiquated root certificates or legacy-supported domains may still reside in trust stores, potentially allowing for the unauthorized issuance of forged X.509 certificates.