title: Prevent image hotlinking in Google Image Search
body: <p>Just recently, Google has introduced a new interface of their Image Search. From January 25 2013 on, full size images are shown directly inside Google, without sending visitors to the source site. I came across a site, that apparently has developed a sophisticated approach to prevent users from grabbing images from Google by introducing some sort of watermark <strong>dynamically</strong>. To see this, please search on the new Google Image Search interface for images by "fansshare.com". This link should be working: <a href="https://www.google.com/search?hl=en&amp;tbo=d&amp;tbm=isch&amp;q=jessica%20biel%20gq&amp;oq=&amp;gs_l=&amp;biw=1183&amp;bih=708&amp;sei=3VkXUcLdFsnHswbd4oHIDQ#hl=en&amp;tbo=d&amp;tbm=isch&amp;sa=1&amp;q=site%3afansshare.com&amp;oq=site%3afansshare.com&amp;gs_l=img.3...0.0.2.10846.0.0.0.0.0.0.0.0..0.0...0.0...1c..2.img.AWfe_f3vWxE&amp;bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&amp;bvm=bv.42080656,d.Yms&amp;fp=da7d521736767550&amp;biw=1183&amp;bih=708">Google Image Search</a>. If not, simply enter "site:fansshare.com" in Google search input filed. Be sure to be on the new search interface, though.</p>
  
  <p>How does fansshare.com achieve this? I couldn't figure it out ...</p>
  
  <p><strong>Update:</strong></p>
  
  <p>fansshare.com adds a GET param to all of their image URLs, like <em>?rnd=69</em>. Example image URL:
  <a href="http://fansshare.com/media/content/570_Jessica-Biel-talks-Kate-Beckinsale-Total-Recall-fight-5423.jpg?rnd=62">http://fansshare.com/media/content/570_Jessica-Biel-talks-Kate-Beckinsale-Total-Recall-fight-5423.jpg?rnd=62</a></p>
  
  <p>This image URL works for a few calls or seconds, after which a redirect takes place to a cached, watermarked image:
  <a href="http://fansshare.com/cached/?version=media/content/570_Jessica-Biel-talks-Kate-Beckinsale-Total-Recall-fight-5423.jpg&amp;rnd=5810">http://fansshare.com/cached/?version=media/content/570_Jessica-Biel-talks-Kate-Beckinsale-Total-Recall-fight-5423.jpg&amp;rnd=5810</a></p>
  
  <p><strong>Edit:</strong></p>
  
  <p>We have finally managed to fully mimic FansShare's hotlink protection and we've published our findings in the following, extensive blog post:</p>
  
  <p><strong><a href="http://pixabay.com/en/blog/posts/hotlinking-protection-and-watermarking-for-google-32/">http://pixabay.com/en/blog/posts/hotlinking-protection-and-watermarking-for-google-32/</a></strong></p>