  An authentic digital signature scheme based on the correlation of
Greenberger-Horne-Zeilinger (GHZ) states was presented. In this scheme, by
performing a local unitary operation on the third particles of each GHZ
triplet, Alice can encode message M and get its signature S. Bob performs CNOT
operation on the combined GHZ triplets can recovery the message M and directly
authenticates Alice's signature S. Our scheme was designed to use quantum
secret key to guaranteed unconditional security, as well as use quantum
fingerprinting to avoid trick attacks and reduce communication complexity.
