NaCl (pronounced "salt") is a new easy-to-use high-speed software
library for network communication, encryption, decryption, signatures,
etc. NaCl's goal is to provide all of the core operations needed to
build higher-level cryptographic tools.

Of course, other libraries already exist for these core operations.
NaCl advances the state of the art by improving security, by improving
usability, and by improving speed.

WWW: https://nacl.cr.yp.to/