I've factored the RSA keys of a Certificate Authority from the 90s

In a recent exploration of the security of RSA cryptography, an individual has factored the RSA keys of a Certificate Authority from the 1990s. RSA's security relies on the difficulty of factoring large semiprime numbers, but the definition of "large" is significant. By the 90s, there were no standards or minimum requirements for RSA keys, leading to the factoring of small RSA keys on modest desktop computers.

The individual downloaded archives of old root certificates from Internet Explorer and Netscape, which were then factored using the CADO-NFS algorithm on a Ryzen 9 5950X desktop. This process took 32 hours for the E-Certify RSA 512 Gold Server and 29 hours for the E-Certify RSA 512 Gold Client. The public keys of these root certificates can be used to reconstruct the private key, allowing for the issuance of certificates that would work in Netscape 4.51.

The factored private keys and tools are available in a GitHub repository, along with instructions for setting up a custom old-timey TLS server. The individual also factored a code signing CA from Internet Explorer 3.02.