ZeroDB [http://www.zerodb.io/] is an end-to-end encrypted database. 
Data can be stored on untrusted database servers without ever exposing the 
encryption key. Clients can execute remote queries against the encrypted data
without downloading it or suffering an excessive performance hit.

Brief description of the protocol: http://blog.zerodb.io/a-peek-under-the-hood/.

Based on ZODB