title: Restrict site access to QR scans only
body: <p>I saw a few questions out there already about ensuring site access comes from QR code scans, but they seemed to be focused on analytics purposes (tracking where traffic was coming from), whereas my interest is in security/privacy.</p>
  
  <p>I want to set up a site that can only be accessed when a provided QR code is scanned. In other words, I don't want the URL that the QR code possesses to be able to just be manually typed/pasted in for site access via other means.</p>
  
  <p>I've been googling this issue for a bit with no luck whatsoever. I'm trying to think of a way with referring URLs or other means to ensure that a person arrived at the site by actually scanning the provided QR code.</p>
  
  <p>EDIT: The solution would need to be scanner-independent as well (i.e. I cannot force users to download and use a specific QR scanner app) and cross-platform (Android + iOS + WinMo + BlackBerry, etc.).</p>
  
  <p>Now I submit the issue to you wonderful folks.</p>