中文摘要：

安全协议未采用适当的密码系统来实现，会使最终的安全协议存在密码系统相关缺陷．对该类缺陷进行形式化分析时，不能使用完善的密码系统假设，这是安全协议形式化分析研究中的一个难点,以CKT5逻辑为基础，以对称密码算法为重点，将序列密码算法和分组密码算法的特性，以逻辑推理规则的形式引入到CKT5逻辑框架中，使得扩展后的逻辑能够用于分析安全协议密码系统相关缺陷,并用实例说明了如何使用扩展逻辑来分析密码系统相关缺陷.

英文摘要：

A security protocol implemented with an improper cryptosystem may have cryptosystem-related flaws. It is difficult to analyze this kind of flaws because the perfect encryption hypothesis cannot be used. CKT5 logic is extended. Focused on the symmetric key cryptography ,the properties of the stream cipher and the block cipher are introduced into the logical framework of CKT5 in the form of logical inference rules, which make the extended logic to be capable to analyze the cryptosystem-related flaws. An examole is given to illustrate how to use the extended logic to analyze the cryptosystem-related flaws.