Reverse Engineering data from Lucene/Solr Indexes

I am investigating whether it is feasable to deploy search servers to the cloud and one of the questions I had revolved around data security. Currently all of our fields (except a few used for faceting) are indexed and not stored (except for the ID, which we use开发者_运维知识库 to retrieve the document after search has completed).

If for some reason the servers within the cloud were compromized, would it be possible for that person to reverse engineer our data from the indexes even without the fields being stored.

Depends on the security level you need and the sensitivity of the document content...

With a configuration you describe it wouldn't be possible to rebuild the original as a "clone"... BUT it would be possible to reverse enough information to gain a lot of knowledge about the content... depending on the context this could be damaging...

An important point:

If you use the cloud based servers to build the index and they get compromized THEN there would be no need for "reversing" depending on your configuration: at least for any document you index after the servers get compromized because for building the index the document gets sent over as it is (for example when using http://wiki.apache.org/solr/ExtractingRequestHandler)...

As Yahia says, it's possible to get some information. If you're really concerned about this, use an encrypted file system, as Amazon suggests.