BearSSL is an implementation of the SSL/TLS protocol (RFC 5246) written
in C. It aims at offering the following features:

- Be correct and secure. In particular, insecure protocol versions and
choices of algorithms are not supported, by design; cryptographic
algorithm implementations are constant-time by default.

- Be small, both in RAM and code footprint. For instance, a minimal server
implementation may fit in about 20 kilobytes of compiled code and 25
kilobytes of RAM.

- Be highly portable. BearSSL targets not only "big" operating systems
like Linux and Windows, but also small embedded systems and even special
contexts like bootstrap code.

- Be feature-rich and extensible. SSL/TLS has many defined cipher suites
and extensions; BearSSL should implement most of them, and allow extra
algorithm implementations to be added afterwards, possibly from third
parties.

WWW: https://bearssl.org/