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vitorenesduarte / spdz

Implementation of the online phase of SPDZ - a MPC protocol - relying on a trusted dealer to generate the data needed from the preprocessing phase
GNU General Public License v3.0
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Save MAC Shares with values and check MACs after N openings #5

Closed vitorenesduarte closed 9 years ago

vitorenesduarte commented 9 years ago

To protect the parties against malicious parties the shared MACs of all opened values need to be checked for correctness, and this must be done in a way so that neither the MAC key nor the MAC value itself is revealed. This is done using the protocol described in here.

vitorenesduarte commented 9 years ago

Initial commit eb8ff56fdca0dbddb8a861d80bd717fd3d7c1c35. Missing:

vitorenesduarte commented 9 years ago

This describes what was to be done.

Not as easy as it sounded.

vitorenesduarte commented 9 years ago

Ideas stolen from here.

vitorenesduarte commented 9 years ago

POC of this protocol.

vitorenesduarte commented 9 years ago

Questions: 1 - each players has a share of the Fixed MAC Key α. But in the extended representation (ER) is created βi's for all players. Can these be the α shares of each player? Why? 2 - if not, can these βi's be the same for all ER? 3 - the [[u]] used as ei, can be the same for all Batch-MAC-Check?

vitorenesduarte commented 9 years ago

3 - No, if that was a possibility, we might as well have this value opened before evaluating the circuit.