We propose a new double-server blind quantum computation protocol based on the Greenberger–Horne–Zeilinger (GHZ) state. In this protocol, the correlation of the GHZ triplets has been utilized to deal with the existing double-server blind quantum computation protocol’s limitation, in which two servers cannot communicate with each other. Moreover, although the two servers in this protocol can obtain different parts of the particles in different GHZ states, they cannot match every GHZ state particle correctly, and this is because the positions of the particles are kept secret. Therefore, the protocol is still secure, in which two servers can communicate with each other. Furthermore, the client can make authentication requests to the trusted center, determining if the first server is honest or not by calculating measurements of part of the GHZ particles. After analyzing the security of the protocol, the protocol is found to be unconditionally secure.
We propose a new double-server blind quantum computation protocol based on the Greenberger–Horne–Zeilinger (GHZ) state. In this protocol, the correlation of the GHZ triplets has been utilized to deal with the existing double-server blind quantum computation protocol’s limitation, in which two servers cannot communicate with each other. Moreover, although the two servers in this protocol can obtain different parts of the particles in different GHZ states, they cannot match every GHZ state particle correctly, and this is because the positions of the particles are kept secret. Therefore, the protocol is still secure, in which two servers can communicate with each other. Furthermore, the client can make authentication requests to the trusted center, determining if the first server is honest or not by calculating measurements of part of the GHZ particles. After analyzing the security of the protocol, the protocol is found to be unconditionally secure.
Blind quantum computation (BQC) enables a client without enough quantum power to delegate his quantum computation to a quantum server, while keeping the input data, the algorithm and the result unknown to the server. In the studies of practical BQC protocol, an important problem is how to reduce the quantum requirement of the client. Multi-server BQC protocols have been proposed to solve this problem. We review the double-server and triple-server protocols [Li et al., Phys. Rev. A 89, 040302(R) (2014)], and propose a modified double-server BQC protocol with a trusted center. In our protocol, the servers are allowed to communicate mutually, and the client is completely classical. Furthermore, our double-server protocol can be modified into a single-server protocol by simply combining the two servers. Compared with the triple-server protocol, our double-server and single-server protocols are more simple and the client is not required to have the ability to access quantum channel. So our protocols are more practical when quantum computer is applied in the `cloud' model.
In blind quantum computation (BQC) protocol, the quantum computability of servers are complicated and powerful, while the clients are not. It is still a challenge for clients to delegate quantum computation to servers and keep the clients' inputs, outputs and algorithms private. Unfortunately, quantum channel noise is unavoidable in the practical transmission. In this paper, a novel BQC protocol based on maximally entangled Greenberger-Horne-Zeilinger (GHZ) states is proposed which doesn't need a trusted center. The protocol includes a client and two servers, where the client only needs to own quantum channels with two servers who have full-advantage quantum computers. Two servers perform entanglement concentration used to remove the noise, where the success probability can almost reach 100% in theory. But they learn nothing in the process of concentration because of the no-signaling principle, so this BQC protocol is secure and feasible.
Secure multi-party extremum, as a significant offshoot of secure multi-party computation, has extensive applications in various domains, including healthcare, financial transactions, market analysis, sports events, etc. Nevertheless, most existing secure multi-party extremum protocols rely on computational hard problems and are thus vulnerable to quantum algorithms. This paper presents a quantum secure multi-party extremum protocol that is built upon the correlations of Greenberger–Horne–Zeilinger (GHZ) states. Within this protocol, multiple participants, with the aid of a semi-honest third party, can obtain the maximum and minimum values of their secret inputs. GHZ states act as the information carriers and are transmitted among the participants and the third party. Their unique correlations ensure the secure transmission of quantum particles. The analysis demonstrates that the proposed protocol is capable of not only warding off common external attacks but also resisting internal attacks launched by dishonest participants and the semi-honest third party. Moreover, the protocol boasts correctness and high scalability.
Blind quantum computation is a new secure quantum computing protocol where a client, who does not have enough quantum technologies at her disposal, can delegate her quantum computation to a server, who has a fully fledged quantum computer, in such a way that the server cannot learn anything about the client's input, output, and program. If the client interacts with only a single server, the client has to have some minimum quantum power, such as the ability of emitting randomly rotated single-qubit states or the ability of measuring states. If the client interacts with two servers who share Bell pairs but cannot communicate with each other, the client can be completely classical. For such a double-server scheme, two servers have to share clean Bell pairs, and therefore the entanglement distillation is necessary in a realistic noisy environment. In this Letter, we show that it is possible to perform entanglement distillation in the double-server scheme without degrading the security of blind quantum computing.
After quantum computers come out, governments and rich companies will have the abilities to buy these useful quantum computers, meanwhile they are familiar with these technologies proficiently. If a client wants to perform quantum computing but she does not have quantum computers with relevant quantum technologies. She can seek help from the server and pay his salary, but she does not want to leak anything to the server. Blind quantum computing (BQC) give a good method for the client to realized her quantum computing. In this article, we propose a new BQC protocol of quantum fourier transform (QFT) performed on multi-qubit states with a trusted, a client and a server, where the trusted center can generate resource states, the client can delegate her quantum computing to a server who can perform universal quantum computing without knowing anything about the client's inputs, algorithms and outputs. We first give the BQC protocols of three-qubit QFT with the equivalently quantum circuits, Greenberg-Horne-Zeilinger(GHZ) entangled states and W entangled states as examples. Further, we extend them to multi-qubit QFT on multi-qubit with the equivalently quantum circuits. At last, we give the analyses and proofs of the blindness and correctness.
With the development of quantum computers, traditional communication security based on classical computers can no longer guarantee unconditional security. At the same time, a series of encrypted communication solutions that rely on quantum mechanical properties have been spawned. This article focuses on the field of quantum signatures, based on the entangled Greenberger–Horne–Zeilinger state, combining group signatures (any member of the group can sign on behalf of the group) and blind signatures (the signer cannot know the accuracy of the signature content) proposed a new quantum group blind signature scheme that utilizes quantum key distribution to achieve unconditional security. By splitting the original message, the scheme strengthens the relevance of the signature participants and makes the signature to have stronger binding. Then, the security of the scheme against internal and external attacks is analyzed. In this scheme, a pleasing efficiency has been achieved, and the non-repudiation of signatures has been enhanced. At the same time, disputed signatures can be traced back to the signer.