From Auditable Quantum Authentication to Best-of-Both-Worlds Multiparty Quantum Computation with Public Verifiable Identifiable Abort

We construct the first secure multiparty quantum computation with public verifiable identifiable abort (MPQC-PVIA) protocol, where PVIA security enables outside observers with only classical computational power to agree on the identity of a malicious party in case of an abort. Moreover, our MPQC is the first quantum setting to provide Best-of-Both-Worlds (BoBW) security, which attains full security with an honest majority and is secure with abort if the majority is dishonest. At the heart of our construction is a generic transformation called Auditable Quantum Authentication (AQA) that publicly identifies the malicious sender with overwhelming probability. Our approach comes with several advantages over the traditional way of building MPQC protocols. First, instead of following the Clifford code paradigm, our protocol can be based on a variety of authentication codes. Second, the online phase of our MPQC requires only classical communications. Third, our construction can achieve distributed computation via a carefully crafted protocol design, which can be adjusted to an MPQC that conditionally guarantees output delivery.