libsodium

A modern, easy-to-use software library for encryption, decryption, signatures, and password hashing.

Libsodium is a portable fork of NaCl that provides a high-level API for critical cryptographic operations. It eliminates common pitfalls by using a misuse-resistant design (no manual nonce management or cipher mode selection required). Developers rely on its core primitives like Curve25519 for key exchange, ChaCha20-Poly1305 for authenticated encryption, and Argon2 for password hashing. The library is written in C, supports over 10 programming languages via bindings, and runs natively on everything from ARM-based IoT devices to x86_64 servers.

https://libsodium.org