Zero-knowledge proofs and the total-knowledge status quo

There are also sorts of processes out there that are really about proof but rarely stated this way.  When you call the bank and verify your identity your mother's maiden name, they are not interested in the name per se but the proof that you know it.  Record linkage processes behind the scenes essentially operate on proof, done in the CPU of a computer, that a collection of records all refers to the same person in real life - just what a person's name is doesn't matter, but how it corresponds to other names in other records.  It's not a term in wide circulation, but you might call these total-knowledge proofs in that the information about the names is exposed.

There is a cryptographic technique called a zero-knowledge proof that allows these linkages and verifications to be performed without giving away anything about the data in question.  They are a natural fit for the P.I.I. (personally identifiable information) held by businesses about consumers, as this information is rarely of interest in it's own right but is instead used for the sort of matching and identification mentioned.  Capnion's position is that these zero-knowledge methods should replace their total-knowledge counterparts throughout the economy, eliminating the need for many businesses to ever hold unencrypted data on consumers.