Active secure four-party computation with an honest majority

Secure multiparty computation (MPC) enables a set of parties to securely carry out a joint computation of their private inputs without revealing anything but the output. Protocols for semi-honest adversaries guarantee security as long as the corrupted parties run the specified protocol and ensure that nothing is leaked in the transcript. In contrast, protocols for malicious adversaries guarantee security in the presence of arbitrary adversaries who can run any attack strategy. Secret sharing plays an important role for maintaining privacy during the computation. In 2020, the authors Dalskov A., Escudero D., Keller M. introduced a new four-party honest-majority MPC protocol with active security that achieves comparable efficiency to equivalent protocols in the same setting, while having a much simpler design and not relying on functiondependent preprocessing. The authors did not provide a complete protocol. This paper provides a complete protocol for secure multiparty computation.