  In this paper, we present an (n, n) threshold quantum secret sharing scheme
of secure direct communication using Greenberger-Horne-Zeilinger state. The
present scheme is efficient in that all the Greenberger-Horne-Zeilinger states
used in the quantum secret sharing scheme are used to generate shared secret
messages except those chosen for checking eavesdropper. In our scheme, the
measuring basis of communication parties is invariable and the classical
information used to check eavesdropping needs only the results of measurements
of the communication parties. Another nice feature of our scheme is that the
sender transmit her secret messages to the receivers directly and the receivers
recover the sender's secret by combining their results, different from the QSS
scheme whose object is essentially to allow a sender to establish a shared key
with the receivers. This feature of our scheme is similar to that of quantum
secret direct communication.
