I am going to build a site using Google App Engine. My public site contains thousands of pictures. I want to store these pictures in the Cloud: Google Storage or Amazon S3 or Google App Engine BlobStore. The problem is image hotlinking.
As for Google Storage, I googled and I cant find a way to prevent image hotlinking. (I like its command line tool gsutil very much though)
Amazon S3 has "Query String Authentication" which generates expiring image urls. But this is very bad for SEO, isnt it? Constantly changing the URL would have quite negative affects as it takes upwards of a year to get an image, and its related URL, into Google Images. I am rather sure changing this URL would have an immediate negative affect when GoogleBot comes around to say hi. (UPDATE: A better way to preven image hotlinking in Amazon S3 by referrer is using Bucket Policy. Details here: http://www.naveen.info/2011/03/25/amazon-s3-hotlink-prevention-with-bucket-policies/)
Google App Engine BlobStore? I have to upload the images via Web Interfaces manually and
it generates changing urls too. (update: Due to my ignorance about Blobstore, I just made a mistake. By using Google App Engine BlobStore, you can use whatever url to serve the image you want.)
What I need is simple referrer protection: Only show the image when the referrer is my site.
Are there some better ways to prevent image hotlinking. I dont want to file bankruptcy due to the extremely high cost of cloud bandwidth.
UPDATE:
Still difficult to choose from the three, each of them have pros and cons. BlobStore seems to be the ultimate choice.