title: Why am I getting this error on Heroku but not locally?
body: <p>TypeErrorserver/models/User.js:143
  Object # has no method 'pbkdf2Sync'</p>
  
  <p>The app works fine locally.</p>
  
  <pre><code>var crypto = require('crypto');
  
  encryptPassword: function(password) {
      if (!password || !this.salt) return '';
      var salt = new Buffer(this.salt, 'base64');
      return crypto.pbkdf2Sync(password, salt, 10000, 64).toString('base64');
  }
  </code></pre>