Publications

Xiaoyu Li, Yue Zhou

In most of the traditional quantum public-key cryptosystems the public key held by the key management center (KMC) is a group of quantum systems. The public key will be destroyed after a secret communication process. So users must reconstruct the public key with KMC after every communication process or keep many copies of public key in the beginning. It’s an obstacle for the quantum cryptosystem to apply in practice. A quantum public-key cryptosystem with reusable (public key privtate key) pair using the bell states is provided in this paper. Every user shares a set of entangled quantum systems in the Bell states with KMC as his or her (public key, private key) pair. Two users can acomplish secret comminications by the help of KMC. Moreover the states of the quantum systems turn back to their original states. The user’s (public key, private key) pair is unchanged so that they are reusable. It’s unnecessary for users to reconstruct the public key with KMC or save many copies of public key in KMC. So this public-key cryptosystem is of much lower management expenses. It’s easier to realized in practice than most of traditional quantum public-key cryptosystems.

Oded Goldreich

Jan Peřina

Xiaoyu Li, Yang Zhou

In most traditional quantum public-key cryptosystems, the public key held by the key management center (KMC) is a group of quantum systems. The public key is destroyed after a secret communication process, and so users must reconstruct the public key with the KMC after every communication process or hold many copies of the public key in the beginning. This requirement is an obstacle to the practical application of such quantum cryptosystems. This paper describes a quantum public-key cryptosystem with reusable keys using entangled states. Each user shares a set of entangled quantum systems with the KMC as that individual user’s (public key, private key) pair. Two users can exchange secret communications with the help of the KMC. Moreover, the states of the quantum systems revert to their original states. The user’s (public key, private key) pair is unchanged so that the keys are reusable. It is unnecessary for users to reconstruct the public key with the KMC or save many copies of the public key in the KMC. As a result, this public-key cryptosystem is much less expensive to manage and easier to realize in practice than most traditional quantum public-key cryptosystems.

Min Liang, Li Yang

Public-key cryptosystems for quantum messages are considered from two aspects: public-key encryption and public-key authentication. Firstly, we propose a general construction of quantum public-key encryption scheme, and then construct an information-theoretic secure instance. Then, we propose a quantum public-key authentication scheme, which can protect the integrity of quantum messages. This scheme can both encrypt and authenticate quantum messages. It is information-theoretic secure with regard to encryption, and the success probability of tampering decreases exponentially with the security parameter with regard to authentication. Compared with classical public-key cryptosystems, one private-key in our schemes corresponds to an exponential number of public-keys, and every quantum public-key used by the sender is an unknown quantum state to the sender.