[nathan_long]

Not necessarily... My pitiably incomplete understanding of something called "fully homomorphic encryption" is that it offers the possibility of letting someone else do operations (math, search, etc) on your encrypted data, giving you useful results, without them ever actually seeing the plaintext data.

My understanding is that this is still in the experimental stage.

[fauigerzigerk]

My understanding of encryption is probably no more complete than yours, but any operation that can give me useful search results necessarily reveals a lot about the content. That's the point of search after all.