s2n-tls API

The API exposed by s2n-tls is the set of functions and declarations that are in the s2n.h header file. Any functions and declarations that are in the s2n.h file are intended to be stable (API and ABI) within major version numbers of s2n-tls releases. Other functions and structures used in s2n-tls internally can not be considered stable and their parameters, names, and sizes may change.

Read Error Handling for information on processing API return values safely.

The VERSIONING.rst document contains more details about s2n's approach to versions and API changes.

API Reference

s2n-tls uses Doxygen to document its public API. The latest s2n-tls documentation can be found on GitHub pages.

The doxygen documentation should be used in conjunction with this guide.


To understand the API it may be easiest to see examples in action. s2n-tls's bin directory includes an example client (s2nc) and server (s2nd).

Note: s2nc and s2nd are intended for testing purposes only, and should not be used in production.