Sparrowvsrevolution writes "CryptDB, a piece of database software that MIT researchers presented at the Symposium on Operating System Principles in October, allows users to send queries to an encrypted SQL database and get results without decrypting the stored information. CryptDB works by nesting data in several layers of cryptography (PDF), each of which has a different key and allows a different kind of simple operation on encrypted data. It doesn't work with every kind of calculation, and it's not the first system to offer this sort of computation on encrypted data. But it may be the only practical one. A previous crypto scheme that allowed operations on encrypted data multiplied computing time by a factor of a trillion. This one adds only 15-26%."