TLS Certificate Optimization: The Technical Details behind “No Browser Left Behind”
Overview
Back in early December we announced our "no browser left behind" initiative to the world. Since then, we have served well over 500 billion SHA-1 certificates to visitors that otherwise would not have been able to communicate securely with our customers’ sites using HTTPS. All the while, we’ve continued to present newer SHA-2 certificates to modern browsers using the latest in elliptic curve cryptography, demonstrating that one does not have to sacrifice security to accommodate all the world’s Internet users. (If you weren’t able to acquire a SHA-1 certificate before CAs ceased issuing them on 2015/12/31, you can still sign up for a paid plan and we will immediately generate one to serve to your legacy visitors.)
Shortly after we announced these new benefits for our paid Universal SSL customers, we started hearing from other technology leaders who were implementing (or already had implemented) similar functionality. At first glance, the logic to identify incoming connections that only support SHA-1 seems straightforward, but as we spoke with our friends at Facebook, Twitter, and Mozilla, I realized that everyone was taking a slightly different approach. Complicating the matter even further was the fact that at CloudFlare we not only Continue reading



Amazon is still a speck on the horizon, though.

