Joken Signer Config

Lightweight way to organize and choose Joken signer configuration based on the contents of individual jwt tokens.

What this solves

The most common use case will probably be in letting your app know which secrets, public keys, and algorithms to use for certain issuers.

Lets say you are building an app that needs to verify a number of jwt tokens from various issuers. Each issuer might need a different algorithm and secret. Or maybe you are willing to accept a limited set of algorithms from a specific issuer that you might not be willing to do with another.

What it does

Given a list of %Joken.Signer.Configs that look like this

      my_list_of_configs = [
        %Joken.Signer.Config{
          headers: %{ alg: "HS256" },
          claims: %{ iss: "some_issuer" },
          signer: fn _ -> Joken.hs256("my_secret") end
        },
        %Joken.Signer.Config{
          headers: %{ alg: "HS256" },
          claims: %{ iss: "some_other_issuer" },
          signer: fn _ -> Joken.hs512("some_other_secret") end
        },
        #...more Signer Configs...
      ]

and a jwt token with contents like this

    my_token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzb21lX2lzc3VlciIsInVzZXIiOiJKYW5lIERvZSJ9.07Od3YbENjGG9yAgErAEJe8CAvguIOG7JhcXs91nyk8"
    
    # headers
    # {
    #   "alg": "HS256",
    #   "typ": "JWT"
    # },
    
    # claims
    # {
    #   "iss": "some_issuer",
    #   "user": "Jane Doe"
    # }

We can call on Joken.Signer.Config to find the correct signer

    Joken.Signer.Config.get(my_list_of_configs, my_token)

    %Joken.Signer{
      jwk: %{"k" => "bXlfc2VjcmV0", "kty" => "oct"},
      jws: %{"alg" => "HS256"}
    }

Installation

If available in Hex, the package can be installed by adding joken_signer_config to your list of dependencies in mix.exs:

def deps do
  [
    {:joken_signer_config, "~> 0.1.0"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/joken_signer_config.