title: Is ActiveSupport::MessageVerifier from Rails 3.2 production-ready?
body: <p>Part of our team is working to upgrade our large codebase from Rails 3.2 to 4.2.</p>
  
  <p>Before that is finished, I'd already like to use <code>ActiveSupport::MessageVerifier</code> for a new feature. The release notes for 4.1 <a href="http://guides.rubyonrails.org/4_1_release_notes.html#message-verifiers" rel="nofollow">included them</a> so I naturally assumed they were introduced in 4.1.</p>
  
  <p>I was trying to estimate the effort of backporting <code>ActiveSupport::MessageVerifier</code> to Rails 3. Going through <a href="https://github.com/rails/rails/commits/master/activesupport/lib/active_support/message_verifier.rb" rel="nofollow">its history</a>, I discovered that the <a href="https://github.com/rails/rails/commit/d460c9a25560f43e7c3789abadf7b455053eb686" rel="nofollow">original commit</a> has been included in Rails core since 2.3.0.</p>
  
  <p>Now I wonder:</p>
  
  <p><strong>Is it safe to use the <a href="https://github.com/rails/rails/blob/3-2-stable/activesupport/lib/active_support/message_verifier.rb" rel="nofollow">message verifier shipped in 3.2</a> in production?</strong></p>