Signaturex 
Simple key/secret based authentication for APIs (documentation).
Totally based on https://github.com/mloughran/signature
Usage
You will need Elixir ~> 1.5 and Erlang ~> 20.0
Client side:
params = %{ q: "asdaf" }
signed_params = Signaturex.sign("key", "secret", :put, "/some/path", params)
params = Map.merge(signed_params, params)
query_string = URI.encode_query(params)
HTTPsomething.put("/some/path?" <> query_string)Server side:
Signaturex.validate("key", "secret", :put, "/some/path", params) # Will return true or false