How CDNs Generate Certificates. Thomas Ptacek (now at Fly) describes in intricate detail the challenges faced by large-scale hosting providers that want to securely issue LetsEncrypt certificates for customer domains. Lots of detail here on the different ACME challenges supported by LetsEncrypt and why the new tls-alpn-01 challenge is the right option for operating at scale.
Recent articles
- My Lethal Trifecta talk at the Bay Area AI Security Meetup - 9th August 2025
- The surprise deprecation of GPT-4o for ChatGPT consumers - 8th August 2025
- GPT-5: Key characteristics, pricing and model card - 7th August 2025