How do I secure my Amazon S3 photos but still make them available via URLs?

I'm planning on making my (family) photo collection available online. I want to use S3 and build an ASP.NET site that will display the photos. I don't want the website to pull down the S3 content and return it to the browser. I want browsers to be able to go directly to S3 without affecting my ASP.NET bandwidth.

It is possible to build URLs for each photo if I set the S3 permission to public, but I only want the photos to be accessible by visitors to my website, not anyone who has the URL.

Any ideas greatly appreciated!

From stackoverflow

• You can generate temporary URLs to secured resources on S3.

  See the bottom of http://docs.amazonwebservices.com/AmazonS3/2006-03-01/index.html?RESTAuthentication.html