Deploying TLS 1.3 at scale with Fizz, a performant open source TLS library

What this post added

This post details the development and deployment of Fizz, a C++ TLS library, to implement TLS 1.3 at scale. It highlights Fizz's features such as asynchronous I/O, scatter/gather I/O for zero-copy operations, and support for 0-RTT early data with replay protection. The post also discusses the security benefits of Fizz's explicit state machine design and the challenges faced during deployment, including middlebox interference, and the solutions implemented. Fizz has secured over 50% of Meta's internet traffic and is open-sourced.