Salchicha

A pure-ish Elixir cryptography tool for the Salsa20 and ChaCha20 ciphers.

Installation

The package can be installed by adding salchicha to your list of dependencies in mix.exs:

def deps do
  [
    {:salchicha, "~> 0.3"}
  ]
end

Usage

iex()> key = Salchicha.generate_secret_key()
iex()> nonce = Salchicha.generate_nonce()
iex()> "Hello, World!"
       |> Salchicha.secretbox(nonce, key)
       |> Salchicha.secretbox_open(nonce, key) 
       |> IO.iodata_to_binary()
"Hello, World!"

Background

The purpose of this library is to have a lightweight, NaCl/libsodium compatible tool for symmetric key encryption/decryption that doesn't depend on any other packages or NIFs.

KCl is an impressive pure-elixir NaCl/libsodium library we had previously used for Discord Voice encryption in nostrum. While adding support for newer encryption modes, I opted to remove :kcl in favor of leveraging what was available via erlang's native :crypto module and implementing the rest more adroitly. In this library the functions have been made more general-purpose and have analogues in the NaCl/libsodium API.

NaCl/libsodium (and KCl) has a lot of other functionality for public key cryptography via EC25519, which erlang's :crypto module already supports. I may add some of that here in the future but in the meantime I've just brought over the XSalsa and XChaCha functions.