4  Secure multiparty computation

Where we explain …

There are different solutions to prevent the reconstruction of raw data. One solution is to make sure that no party other than the data owner is actually able to see the intermediate data. One branch of techniques that can be used for this is Secure Multiparty Computation (MPC). With MPC, computations are performed collaboratively by multiple parties. Data is encrypted in such a way that other parties cannot see the original values, but values of multiple parties can still be combined ( e.g. added or multiplied). A classic technique from the field of MPC is secret sharing. With this technique data is encrypted, after which pieces of the encryption are sent to the other parties. No single party will be able to reconstruct the original value. Only when a certain minimum of parties work together (n-1 in many cases) the original value can be retrieved.

When combining multiple values using secret sharing, this will result in the parties owning new puzzle pieces that when put together will reveal the result of the computation.