Three-Party Integer Comparison and Applications
Jie Ma, Bin Qi, Kewei Lv · 2021
Secure integer comparison enables two parties to compare their inputs without revealing the exact value of those inputs. In this paper, we highlight three-party integer comparison (TPIC), where a judge, with no private input, wants to know the comparison result, while two competitors hold secret integers to do privacy-preserving comparison. A TPIC protocol enables the judge to actively obtain the result rather than passively learning it from one of the competitors. We give two TPIC constructions considering mixed adversaries, who have different capabilities. One is secure against semi-honest competitors with low computation and communication cost, while the other is secure against malicious competitors. In both, the judge is semi-honest. As applications of TPIC, we present a joint bidding scheme and a practical auction with brief security proofs and analysis. In comparison, our auction scheme is more efficient with lower cost, making it feasible in practice rather than a theoretical design. The proposed TPIC protocols and application schemes run on top of blockchain requiring a constant number of rounds.