Databases hold vast amounts of personal information including some very sensitive tidbits, creating headaches for the companies that must curate them. Now, sophisticated tools and technologies are making it possible for database developers to have their cake and, to stay in metaphor, not count the calories by keeping the information private.
The solutions depend upon a clever application of math. Some of the simplest mechanisms are just modern versions of secret codes, essentially digital versions of the classic decoder wheel. Others are more complex extensions that push the math to deliver more flexibility and accountability. Many are practical versions of ideas that have been circulating in labs for decades but are finally stable enough to be trusted.