I have been recently working on TLS (Transport Layer Security) libraries, in particular GnuTLS and NSS. For the last few years there had been a lot of activities in upstream implementing the latest standard, which officially came out as TLS 1.3. While the protocol design drastically changed from TLS 1.2, applications usually don’t need to be modified to just enable TLS 1.3; that is a good thing. On the other hand, a new API set is added to support the new concepts in TLS 1.3, such as 0-RTT mode.
In January, I had a chance to talk at DevConf.cz (and later FOSDEM) to go through those new APIs (slides, recording), which I hope application developers might find useful. Note that the APIs are still changing as we continue adding remaining features to the libraries.