Garbled Quantum Computation

Abstract

Abstract:The universal blind quantum computation protocol (UBQC) enables an almost classical client to delegate a quantum computation to an untrusted quantum server (in the form of a garbled quantum circuit) while the security for the client is unconditional. In this contribution, we explore the possibility of extending the verifiable UBQC, to achieve further functionalities following the analogous research for classical circuits (Yao 1986). First, exploring the asymmetric nature of UBQC (the client preparing only single qubits, while the server runs the entire quantum computation), we present a "Yao"-type protocol for secure two-party quantum computation. Similar to the classical setting, our quantum Yao protocol is secure against a specious (quantum honest-but-curious) garbler, but in our case, against a (fully) malicious evaluator. Unlike the previous work on quantum two-party computation of Dupuis et al., 2010, we do not require any online-quantum communication between the garbler and the evaluator and, thus, no extra cryptographic primitive. This feature will allow us to construct a simple universal one-time compiler for any quantum computation using one-time memory, in a similar way to the classical work of Goldwasser et al., 2008, while more efficiently than the previous work of Broadbent et al., 2013.

Multiparty Delegated Quantum Computing

“…It remains to study whether the proposed protocol remains secure against a dishonest coalition between clients and the Server or if there is an unavoidable leakage of information. One equivalent way of studying this problem would be by extending the results of [8] in the multiparty setting, where both the parties and the Server have inputs in the computation. An even more interesting question is whether we can enhance our protocol to include verifiability in a similar way that is done in [9].…”

“…This means that we only prove security against two adversarial models, against a dishonest Server, and against a coalition of dishonest clients. Security in the more general scenario where a Server and some clients collaborate to cheat, remains as an open question (however see [8] for a relevant model with only one client, where the Server is also allowed to provide an input).…”

On the Possibility of Classical Client Blind Quantum Computing

“…More specifically, it could be used in protocols where each party needs to make sure that all the other parties are honest. Three major examples of such applications would be the following: two-party quantum computation [37,38], multiparty quantum computation [39] and quantum one-time programs [40]. Indeed, most of these protocols suffer from the fact that one party could try to cheat by sending malicious states instead of the honest single qubit states.…”

“…The verifiable blind quantum computation protocols in [30,31] or the two-party quantum computation protocols in [37,38], require the honest party to prepare single qubit states from the set of states {|0 , |1 , |+ kπ/4 }. While the QFactory primitive can output the |+ kπ/4 states, in order to make the honest party fully classical, we need to change the construction of QFactory in order to also be able to output the |0 and |1 states, and maintain the same guarantees in privacy as in the QFactory.…”

Verification of Quantum Computation:An Overview of Existing Approaches

“…the prover returns a quantum state to the verifier). Such a situation is particularly useful when composing verification protocols [19,[49][50][51]]. 14 One could imagine this happening if, for instance, the prover provides random responses to the verifier instead of performing the desired computation C. Definition 3 (δ-correctness) Consider a delegated quantum computation protocol between a verifier and a prover.…”