I'VE FACTORED THE RSA KEYS OF A CERTIFICATE AUTHORITY FROM THE '90S

Summary from the TLDR Dev newsletter

Matthew McPherrin found two 512-bit E-Certify root certificates shipped with Netscape in 1999 and factored each key on a desktop in about 30 hours. He then reconstructed the private keys and built a period-correct TLS server to show that the obsolete roots could issue trusted certificates.