Fun read about how the challenges were generated, available on the Internet Archive Wayback Machine. 1. 30,000 bytes were generated with a HWRNG on a laptop. 2. Those bytes seeded the B_GenerateKeyPair function in RSA BSAFE. 3. The private key was discarded. 4. The public key was exported. 5. The moduli was extracted and converted to decimal. 6. The laptop hard drive was destroyed. https://web.archive.org/web/20130921043454/http://emc.com/emc-plus/rsa-labs/historical/the-rsa-factoring-challenge-faq.htm#HowWereTheNumbersGenerated