Researcher Factors 512-bit RSA Keys from a 1990s Certificate Authority
Original: I've factored the RSA keys of a Certificate Authority from the 90s
Why This Matters
Demonstrates that legacy PKI roots can be fully compromised with commodity hardware, underscoring the urgency of deprecating weak cryptographic standards.
Security researcher Matthew McPherrin successfully factored two 512-bit RSA root certificate keys from defunct Canadian CA E-Certify, originally shipped with Netscape 4.51 in March 1999, using a Ryzen 9 5950X desktop over 29–32 hours with CADO-NFS software.
Matthew McPherrin, a security researcher, factored the RSA private keys of two root certificates issued by the long-defunct Canadian Certificate Authority E-Certify, which were bundled with Netscape 4.51 in March 1999. The two certificates — one trusted for SSL and one for S/MIME — used 512-bit RSA keys, a size already considered dangerously weak even at the time: RSA-155 (also 512-bit) was publicly factored later that same year in 1999. McPherrin used the open-source CADO-NFS factoring tool on a consumer-grade AMD Ryzen 9 5950X desktop, completing the SSL root in 32 hours and the S/MIME root in 29 hours. He retrieved archived Netscape and Internet Explorer installers from archive.org and used Claude Code to extract the embedded root certificates. Internet Explorer never shipped 512-bit SSL roots, making E-Certify roots unique to Netscape. The E-Certify roots were removed by Netscape in 2002 and expired in October 2003. McPherrin reconstructed the private keys and built a custom legacy TLS server in Go to verify that certificates signed with the recovered keys would be accepted by Netscape 4.51. The private keys and tools have been published on GitHub at github.com/mcpherrinm/ancientroots. Today, 2048-bit RSA is the minimum standard, and post-quantum migration is already underway.