title: Password hashing - how to upgrade?
body: <p>There's plenty of <a href="https://stackoverflow.com/questions/2768248/is-md5-really-that-bad">discussion</a> on the best algorithm - but what if you're already in production?  How do you upgrade without having to reset on the user?</p>
  
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  <p>EDIT/DISCLAIMER: Although I originally wanted a "quick fix" solution and chose orip's response, I must concede that if security in your application is important enough to be even bothering with this issue, then a quick fix is the wrong mentality and his proposed solution is probably inadequate.  </p>