Quantum Public-Key Cryptosystem Based on Super Dense Coding Technology

In this paper we provide a quantum public-key cryptosystem based on super dense coding technology. A user Alice shares a set of Einstein-Podolsky-Rosen (EPR) pairs with a key management center (KMC) in which the particles hold by Alice are the private key and the particle hold by KMC are the public key. By the help of the key management center any other user can send encrypted message to Alice. Any one including KMC except Alice can't recover the message. On the other hand digital signature can also be achieved by this public-key cryptosystem. In the cryptosystem one EPR pair can be used to encrypt two bits of the plain text. So it's efficient. Finally we prove that our cryptosystem is robust against possible attacks.