Return preconfigured AS::MessageVerifier

railties/CHANGELOG.md

+*   The `Rails.application.message_verifier` now returns ActiveSupport::MessageVerifier
+    preconfigured with `:digest` and `:serializer` values set to `config.action_dispatch.cookies_digest`
+    and `config.action_dispatch.cookies_serializer` accordingly.
+
+    *Łukasz Strzałkowski*
+
 *   Add `after_bundle` callbacks in Rails templates. Useful for allowing the
     generated binstubs to be added to version control.
 

railties/lib/rails/application.rb

@@ -200,7 +200,7 @@ def key_generator
     def message_verifier(verifier_name)
       @message_verifiers[verifier_name] ||= begin
         secret = key_generator.generate_key(verifier_name.to_s)
-        ActiveSupport::MessageVerifier.new(secret)
+        ActiveSupport::MessageVerifier.new(secret, digest: config.action_dispatch.cookies_digest, serializer: config.action_dispatch.cookies_serializer)
       end
     end