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    基于散列时间有效性的轻量级完整性监测方法

    Light-Weight Integrity Monitoring Based on Hashing Time Validity

    • 摘要: 实时监测节点完整性状态是资源受限节点安全保护的有效手段.分析针对资源受限节点的主要篡改攻击模式及对散列时间带来的影响,提出基于散列时间有效性检验的纯软件完整性监测手段.基于对散列时间有效性可检验条件分析,提出采用验证值伪造惩罚系数描述散列模块抗篡改能力,设计一种融入程序状态的轻量级散列算法,通过简化算法结构与融入程序状态,增大验证值伪造难度,提高验证值伪造惩罚系数.设计支持消息认证的监测协议防止消息伪造,基于验证值比较与散列时间有效性统计,判定节点完整性状态.实验结果表明:该方案以微小的节点开销为代价,获得了更高的散列时间有效性检验可靠性,增强了对散列时间与消息传输时间波动干扰的容忍能力,提高了资源受限节点防篡改攻击性能.

       

      Abstract: Real-time monitoring of node integrity is effective means to protect resource-restrained nodes. By identifying main tampering attack modes against resource-restrained nodes, and analysiing the influence on hashing time, pure-software integrity monitoring means based on inspecting hashing time validity is suggested. On the basis of analysing testability condition of hashing time validity, checksum forging punishment coefficient is proposed to indicate tamper-resisting performance of monitor mechanism, and a light-weight hashing algorithm of merging program states is put forward. By simplifying hashing structure and integrating program states into checksum, checksum forging is made more difficult. Damaged nodes have to spend much more time on extra work like restoring legal code and program states than on hashing if they want to aquire the correct checksum. Hence, the proposed mechanism imposes much greater checksum forging punishment on damaged nodes than other approaches like SWATT and Shah. In order to prevent message forging or tampering during transmission over communication networks, a monitoring protocol supporting message authentication is designed. For tolerating influence from hashing time fluctuation and checksum guess, node integrity state is evaluated from results of both checksum comparison and hashing time validity statistics. The experiments show that the proposed approach achieves high reliabiliy in examining validity of checksum and hashing time with small cost. Toleration ability against fluctuation disturbance on hashing time from node multi-tasking environment and communication networks is improved, and hence tamper-resisting performance of resource-constrained nodes is enhanced.

       

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