【摘要】 铁路信号安全协议-Ⅱ(railway signal safety protocol-Ⅱ, RSSP-Ⅱ)是我国列车控制系统CTCS-3的核心安全通信协议，在保障列车通信安全性与可靠性方面发挥着关键作用。然而，现有研究表明，RSSP-Ⅱ的消息鉴定安全层存在密钥恢复与伪造等安全漏洞，可能危及列车控制系统的稳定运行。针对上述安全问题，使用着色Petri网（colored Petri nets, CPN）形式化建模方法对RSSP-Ⅱ进行了分析，验证了RSSP-Ⅱ中存在安全漏洞，并提出了一种改进协议EN-RSSP(enhanced railway signal safety protocol)。该改进协议主要包含3个方面的增强措施。首先，通过可信第三方在安全信道中动态构建通信双方设备的临时密钥对；其次，基于椭圆曲线双线性对的离散对数困难特性，结合哈希函数实现会话密钥协商；最后，采用由会话密钥和通信双方设备的预共享密钥构成的双密钥加密体系对消息进行加密传输。此外，还在信息交互过程中引入了时间戳和CMAC(cipher-based message authentication code)消息认证码，以确保通信双方消息的保密性和完整性。通过CPN形式化分析工具对EN-RSSP(enhance-RSSP)和RSSP-Ⅱ进行安全评估，结果表明，改进后的协议不仅能有效抵御密钥恢复与伪造攻击，还可防范重放攻击，显著提升了系统的安全性。更多还原

【Abstract】 The railway signal safety protocol-Ⅱ(RSSP-Ⅱ), as the core security communication protocol of China’s train control system(CTCS-3), played a crucial role in ensuring the security and reliability of train communication. However, existing research revealed that RSSP-Ⅱ’s message authentication security layer(MASL) had security vulnerabilities like key recovery and forgery, which might endanger the train control system’s stable operation. To address these security issues, the formal modeling method of colored Petri nets(CPN) was employed to analyze RSSP-Ⅱ, and the existence of security vulnerabilities in it was verified. Consequently, an improved protocol, EN-RSSP(enhanced railway signal safety protocol), was proposed. The improvement primarily comprised three aspects. First, a temporary key pair for the communication devices of both parties was dynamically constructed through a trusted third party in a secure channel. Next, session key negotiation was achieved based on the difficulty of the discrete logarithm problem in elliptic curve bilinear pairing combined with a hash function. Finally, a dual-key encryption system made up of the session key and the pre-shared key of the communication devices of both parties was adopted to encrypt and transmit messages. Moreover, timestamps and CMAC(cipherbased message authentication code) were incorporated into the information exchange process to ensure the confidentiality and integrity of messages between devices. Security assessment of EN-RSSP and RSSP-Ⅱ was conducted using the CPN formal analysis tool. The results show that the improved protocol could not only effectively resist key recovery and forgery attacks, but also prevent replay attacks, thereby significantly enhancing the system’s security.更多还原