Analyzes the security of the signature scheme proposed by Fagen Li, Find its security loopholes by attacking, And for its security loopholes, a new digital signature scheme is given. Its security is based on the difficulty of RSA and DLP, and then repaired the loopholes in the Li and improve the security. Across four kinds of attack ways to analysis the scheme safety, Proved that the situation can not be solved simultaneously in the RSA and DLP. As compared with the Li scheme, The scheme improve the calculation steps and reduce computational complex and communication volume. The complexity of programs are superior to Li.

N-ethyl-3,6-Bisbenzoxazolyl was synthesized from carbazole and 2-Aminophenol.The structure was confirmed by 1H NMR,13C NMR and IR.The optical properties of this compound was systematically studied by UV-Vis absorption and fluorescence spectra.The results showed that this compound might be used as a blue emission material.