(ArgumentError) incorrect padding while running mix local.hex

Question

I'm new to Elixir. In a local folder, I'm trying to run mix local.hex, but it throws this error:

** (ArgumentError) incorrect padding
    (elixir) lib/base.ex:676: Base.do_decode64/2
    (mix) lib/mix/local.ex:91: Mix.Local.find_matching_versions_from_signed_csv!/2
    (mix) lib/mix/tasks/local.hex.ex:30: Mix.Tasks.Local.Hex.run/1
    (mix) lib/mix/cli.ex:58: Mix.CLI.run_task/2
    (elixir) lib/code.ex:363: Code.require_file/2

Here is my mix.exs:

defmodule MyPlug.Mixfile do
  use Mix.Project

  def project do
    [
      app: :my_plug,
      version: "0.0.1",
      elixir: "~> 1.2",
      deps: deps
    ]
  end

  def application do
    [applications: [:cowboy, :plug]]
  end

  defp deps do
    [{:cowboy, "~> 1.0.0"},
     {:plug, "~> 1.0"}]
  end
end

OS: Ubuntu 14.04 LTS
Erlang version: Erlang/OTP 18
Elixir version: 1.2.3

Appreciate your response on what could be wrong here.

Answer 1

For anyone else that may find this question, the answer, which was supplied by the person who asked the question is that in this case his firewall was blocking S3. When he unblocked S3 he was able to do mix local.hex.

Adding the answer and marking it as community wiki.