title: Using MD5 in symfony2 security.yml for legacy users
body: <p>I have a legacy system which contains md5 hashed passwords. I have tested these to be correct and they do not use a salt.</p>
  
  <p><strong>security.yml</strong></p>
  
  <pre><code>security:
      encoders:
          Namespace\MyBundle\Entity\User:
              algorithm: md5
  providers:
      entityUsers:
          entity: { class: NamespaceBundle:User, property: username }
  </code></pre>
  
  <p>In my User entity I have implemented UserInterface and made sure the <strong>salt is set to the empty string</strong>.</p>
  
  <p>But I get a <strong>bad credentials</strong> error when trying to authenticate.</p>
  
  <p>I have tried switching security.yml to plaintext and entered the hash and the system works fine. </p>
  
  <p>Surely md5 should just work?</p>