Cryptographic Combinatorial Clock-Proxy Auctions

We present a cryptographic protocol for conducting efficient provably correct. and secrecy-preserving combinatorial clock-proxy auctions. The "clock phase" functions as a trusted auction despite price discovery: bidders subunit encrypted bids, and prove for themselves that they meet activity rules, and call Compute total demand and thus verify price increases without revealing any information about individual demands. In the sealed-bid "proxy phase", all bids are revealed the auctioneer via, time-lapse cryptography and a branch-and-bound algorithm is used to solve the winner-determination problem. Homomorphic encryption is used to prove the correctness of the solution, and establishes the correctness of the solution to any interested party. Still all NP-hard optimization problem, the use of homomorphic encryption imposes additional computational time on winner-determination that is linear in the size of the branch-and-bound search tree, and thus roughly linear in the original (search-based) computational time. The result is a solution that avoids, in the usual case, the exponential complexity of previous cryptographically-secure combinatorial auctions.