integrate with ccs

app/helpers/uploads_helper.rb

@@ -0,0 +1,9 @@
+module UploadsHelper
+  def ccs_build_sig(url)
+    return nil unless Danbooru.config.ccs_server.present?
+
+    ref = ImageProxy.fake_referer_for(url)
+    digest = OpenSSL::Digest.new("sha256")
+    OpenSSL::HMAC.hexdigest(digest, Danbooru.config.ccs_key, "#{url},#{ref}")
+  end
+end