Searching an Encrypted Document Collection with Solr4, MongoDB and JCE by Sujit Pal.
From the post:
A while back, someone asked me if it was possible to make an encrypted document collection searchable through Solr. The use case was patient records – the patient is the owner of the records, and the only person who can search through them, unless he temporarily grants permission to someone else (for example his doctor) for diagnostic purposes. I couldn’t come up with a good way of doing it off the bat, but after some thought, came up with a design that roughly looked like the picture below:
With privacy being all the rage, a very timely post.
Not to mention an opportunity to try out Solr4.