MessageEncryptor is a simple way to encrypt values which get stored somewhere you don't trust.

The encrypted key, initialization vector, cipher text, and cipher tag are base64url encoded and returned to you.

This can be used in situations similar to the Plug.Crypto.MessageVerifier, but where you don't want users to be able to determine the value of the payload.

The current algorithm used is XChaCha20-Poly1305.

Example

iex> secret_key_base = "072d1e0157c008193fe48a670cce031faa4e..."
...> encrypted_cookie_salt = "encrypted cookie"
...> secret = KeyGenerator.generate(secret_key_base, encrypted_cookie_salt)
...>
...> data = "José"
...> encrypted = MessageEncryptor.encrypt(data, secret, "UNUSED")
...> MessageEncryptor.decrypt(encrypted, secret, "UNUSED")
{:ok, "José"}