The project ProSecCo aims at developing new distributed quantum applications for tasks, which cannot be realized classically. Protocols for secure computations evaluate a function, which depends on local inputs of the participants. The protocols ensure the correctness of the results and do not expose inputs, which should remain secret. The commercial success of quantum technology will rely on such applications. Starting with a quantum security model incorporating realistic threats and faults, we will develop methods for building complex secure protocols from basic primitives. We aim to identify where security can be guaranteed by physics and, where it cannot, to identify reliable technological or computational security assumptions. We will develop new primitives and new applications, which involve entangled states and small scale quantum computations which are feasible in the near future and investigate their practicability in the presence of noise. The project ProSecCo aims at developing new distributed quantum applications for tasks, which cannot be realized classically. Protocols for secure computations evaluate a function, which depends on local inputs of the participants. The protocols ensure the correctness of the results and do not expose inputs, which should remain secret. The commercial success of quantum technology will rely on such applications. Starting with a quantum security model incorporating realistic threats and faults, we will develop methods for building complex secure protocols from basic primitives. We aim to identify where security can be guaranteed by physics and, where it cannot, to identify reliable technological or computational security assumptions. We will develop new primitives and new applications, which involve entangled states and small scale quantum computations which are feasible in the near future and investigate their practicability in the presence of noise.

OBJECTIVES

The idea is to use small scale distributed secure quantum computations to accomplish tasks which are impossible classically. Secure computations allow the participants to jointly compute a function on inputs they hold locally and ensure the correctness of the result and the privacy of the inputs. Everyday examples are authentication, voting schemes, or online auctions. The project will develop new distributed quantum applications and analyse their security against quantum faults/attacks. Such protocols will probably be among the first applications of quantum technology. A further scientific motivation is that new quantum protocols as well as new impossibility theorems will elucidate the borderline between tasks which can be securely implemented with quantum protocols but not classically, and tasks for which physical security guarantees are impossible - A key problem in the field.

DESCRIPTION OF WORK

We propose to develop new distributed quantum applications based on small scale quantum computations, clarify the underlying assumptions, develop methods for the construction of distributed secure computations from primitives, and investigate the practicability of such protocols. The workplan consists of three workpackages. The first (WP 1) investigates the framework in which distributed applications take place. To be able to show the advantages of quantum secure computations over classical solutions one needs a model of threat/security as well as a clear statement of possibly underlying assumptions. Also of interest are new computational assumptions, which take into account quantum computers. Such assumptions are not only important for cryptographic applications, but also exemplify the strengths and weaknesses of quantum computers. In the workpackage WP 2 methods are developed which allow us to combine secure subprotocols to a more complex secure application. This is relatively easy for classical protocols, but difficult in the quantum case where attacks/faults may entangle quantum information over several subprotocols. The proofs of the validity of such constructions rely on the models of security of WP 1.

New primitives as well as new applications will be developed in workpackage three WP 3. As these new applications will in general employ subprotocols the methods of WP 2 are especially useful here. Promising candidates for new primitives are in the area of quantum authentication, quantum coin tossing, new cheat sensitive protocols, and new protocols for secure assisted computations. Special attention in WP 3 and WP 4 is on the use of small-scale quantum computations in distributed applications. A lot of proposed quantum protocols use coherent interaction among few qubits. It is the aim of the project to propose new such applications and investigate the practicability of such small-scale quantum computations.