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The Hydrogen library is a small, easy-to-use, hard-to-misuse cryptographic library.


  • Consistent high-level API, inspired by libsodium. Instead of low-level primitives, it exposes simple functions to solve common problems that cryptography can solve.
  • 100% built using just two cryptographic building blocks: the Curve25519 elliptic curve, and the Gimli permutation.
  • Small and easy to audit. Implemented as one tiny file for every set of operation, and adding a single .c file to your project is all it takes to use libhydrogen in your project.
  • The whole code is released under a single, very liberal license (ISC).
  • Zero dynamic memory allocations and low stack requirements (median: 32 bytes, max: 128 bytes). This makes it usable in constrained environments such as microcontrollers.
  • Portable. Supports Linux, *BSD, MacOS, Windows, and the Arduino IDE out of the box.
  • Can generate cryptographically-secure random numbers, even on Arduino boards.
  • Attempts to mitigate the implications of accidental misuse, even on systems with an unreliable PRG and/or no clock.

This crate implement low-level Rust bindings, that don't require any external dependencies.

The libhydrogen crate provides a high-level idiomatic interface.

Libhydrogen documentation