  In this paper, an efficient arbitrated quantum signature scheme is proposed
by combining quantum cryptographic techniques and some ideas in classical
cryptography. In the presented scheme, the signatory and the receiver can share
a long-term secret key with the arbitrator by utilizing the key together with a
random number. While in previous quantum signature schemes, the key shared
between the signatory and the arbitrator or between the receiver and the
arbitrator could be used only once, and thus each time when a signatory needs
to sign, the signatory and the receiver have to obtain a new key shared with
the arbitrator through a quantum key distribution protocol. Detailed
theoretical analysis shows that the proposed scheme is efficient and provably
secure.
