behe

Apple App Store Server Notifications v2 validation

Background

I recently had to upgrade our backend's handling of App Store Server Notifications to the new v2 version. The old version had pretty basic security by only having a supplied password in the response that you verified with what you had configured it to be in App Store Connect. The new version on the other hand is now in JWS (JSON Web Signature) signed with an Apple X.509 certificate chain. Since it was not straight forward to figure out how to verify this certificate chain and signature I wanted to write down how I was able to do it in Elixir:

The following steps are needed to verify the notifications:

behe

defmodule ATGCCount do
  def count(sequence), do: cnt(String.to_char_list(sequence),0,0)
  def cnt([65|t],at,gc), do: cnt(t,at+1,gc)
  def cnt([84|t],at,gc), do: cnt(t,at+1,gc)
  def cnt([71|t],at,gc), do: cnt(t,at,gc+1)
  def cnt([67|t],at,gc), do: cnt(t,at,gc+1)
  def cnt([62|_],at,gc), do: {at,gc}
  def cnt([],at,gc), do: {at,gc}
  # def cnt(_,0,0), do: {0,0}
  def cnt([_|t], at, gc), do: cnt(t,at,gc)

behe

# Put this is your .profile, .bashrc or similar to automatically reload your .rvmrc after git checkouts

git() { command git "$@" ; if [[ "$@" == *checkout* ]]; then [[ -s .rvmrc ]] && . .rvmrc; fi }

behe

"""
  http://elixirquiz.github.io/2014-08-11-fizzbuzz.html
"""
defmodule FizzBuzz do
  def up_to(n) do
    1..n
    |> Enum.to_list
    |> Enum.map(&transform/1)
    |> Enum.join " "
  end