libsodium

Sodium is a new, easy-to-use software library for encryption, decryption, signatures, password hashing and more.

It is a portable, cross-compilable, installable, packageable fork of NaCl, with a compatible API, and an extended API to improve usability even further.

Its goal is to provide all of the core operations needed to build higher-level cryptographic tools.

Sodium supports a variety of compilers and operating systems, including Windows (with MingW or Visual Studio, x86 and x64), iOS, Android, as well as Javascript and Webassembly.