摘要：目前．我国进入股改阶段的上市公司总市值已经过半．股权分置改革取得了实质性突破．我国股市企盼已久的全流通时代即将来临。本文阐述了在这种形势下适时推出股指期货对推动我国股市发展所具有的战略性意义以及在推出股指期货时应该考虑的合约设计．风险监管体系的建立等方面应该注意的问题。

摘要：在Crypto’05上,Boneh等人提出了两个广播加密方案.他们的工作具有令人振奋的结果:用户的私钥以及广播的密文均为固定长度,与接收者的数目无关.在他们的文章中给出了一个开放性问题,也就是希望能够为他们的广播加密方案设计一个叛逆者追踪算法,并通过对该追踪算法和他们的广播加密方案进行结合,得到一个有效的追踪及撤销系统.文中对该开放性问题给予了否定的回答.具体地说,给出了一种方法,使得3个或3个以上的叛逆者可以合谋出一个针对他们的广播加密方案的盗版解密器,并且还证明了不可能存在追踪算法来找出这些叛逆者.我们的盗版解密器可以类似地应用于Lee等人在ISPEC’06上提出的广播加密方案.

摘要：To deal with the key-exposure problem in signature systems, a new framework named parallel key-insulated signature (PKIS) was introduced, and a concrete PKIS scheme was proposed. Compared with traditional key-insulated signature (KIS) schemes, the proposed PKIS scheme allows a frequent updating for temporary secret keys without increasing the risk of helper key-exposure. Moreover, the proposed PKIS scheme does not collapse even if some (not all) of the helper keys and some of the temporary secret keys are simultaneously exposed. As a result, the security of the PKIS scheme is greatly enhanced, and the damage caused by key-exposure is successfully minimized.