The rationale for a homomorphic encryption system (FHE = fully homomorphic encryption):
“Homomorphic” is a mathematical term meaning that if you do two things to a bit of data – say, encrypt it and process it – the order in which you do them won’t matter. In other words, in FHE, data can be processed after it is encrypted, as well as before. This means that a Gmail user could someday send an encrypted search query to the servers in the cloud, and those severs could carry out that query even though the query and the e-mails are completely inscrutable to them. Only the user who holds secret key can ever decrypt the original data, the query, or the query results.
For another example, imagine how FHE could help the proprietor of an online movie streaming service – call it Hackbuster Video– protect the privacy of customers while still giving them all the features they want. A customer’s request for a new movie would be encrypted, as would the movie itself, meaning that Hackbuster would not know what movie the customer was watching. Despite the privacy, the Hackbuster’s servers could still charge the correct amount, offer playback features such as pause and rewind, and even still make recommendations of similar movies, all without ever being privy to the movies involved.
From: Encryption that allows privacy and access to co-exist earns top dissertation award
Craig Gentry solved this problem (he has a law degree as well) in his dissertation at Stanford.
Not quite ready for prime time due to performance issues but definitely a step in the right direction.
Of interest to topic mappers because of the need for secure interaction with remote topic map facilities.
Additional resources of interest:
Craig Gentry’s dissertation: A fully homomorphic encryption scheme.
Craig’s “easy” version for ACM members: Computing Arbitrary Functions of Encrypted Data. (CACM, March 2010)
Fields Institute Presentation (slides) http://av.fields.utoronto.ca/slides/08-09/crypto/gentry/download.pdf
Fields Institute Presentation (audio) http://www.fields.utoronto.ca:8080/ramgen/08-09/crypto/gentry.rm