Joken

Encodes and decodes JSON Web Tokens.

Supports the following algorithms:

• HS256
• HS384
• HS512

Supports the following claims:

• Expiration (exp)
• Not Before (nbf)
• Audience (aud)
• Issuer (iss)
• Subject (sub)
• Issued At (iat)
• JSON Token ID (jti)

Usage:

First, create a module that implements the Joken.Config Behaviour. This Behaviour is responsible for the following:

• encoding and decoding tokens
• adding and validating claims
• secret key used for encoding and decoding
• the algorithm used

If a claim function returns nil then that claim will not be added to the token. Here is a full example of a module that would add and validate the exp claim and not add or validate the others:

defmodule My.Config.Module do
  @behaviour Joken.Config

  def secret_key() do
    Application.get_env(:app, :secret_key)
  end

  def algorithm() do
    :H256
  end

  def encode(map) do
    Poison.encode!(map)
  end

  def decode(binary) do
    Poison.decode!(binary, keys: :atoms!)
  end

  def claim(:exp, payload) do
    Joken.Config.get_current_time() + 300
  end

  def claim(_, _) do
    nil
  end

  def validate_claim(:exp, payload, options) do
    Joken.Config.validate_time_claim(payload, :exp, "Token expired", fn(expires_at, now) -> expires_at > now end)
  end

  def validate_claim(_, _, _) do
    :ok
  end
end

Joken looks for a joken config with config_module. config_module module being a module that implements the Joken.Config Behaviour.

config :joken,
   config_module: My.Config.Module

then to encode and decode

{:ok, token} = Joken.encode(%{username: "johndoe"})

{:ok, decoded_payload} = Joken.decode(jwt)