Add plug to validate signed http requests.

lib/pleroma/plugs/http_signature.ex

@@ -0,0 +1,19 @@
+defmodule Pleroma.Web.Plugs.HTTPSignaturePlug do
+  alias Pleroma.Web.HTTPSignatures
+  import Plug.Conn
+
+  def init(options) do
+    options
+  end
+
+  def call(conn, opts) do
+    if get_req_header(conn, "signature") do
+      conn = conn
+      |> put_req_header("(request-target)", String.downcase("#{conn.method} #{conn.request_path}"))
+
+      assign(conn, :valid_signature, HTTPSignatures.validate_conn(conn))
+    else
+      conn
+    end
+  end
+end