In wireless sensor networks (WSNs), security, efficiency, and energy consumption are still major challenges due to its open, large-scale, and resource-constrained nature. The 6LoWPAN protocol and many other lightweight cryptographic methods have been developed to improve the security and efficiency of WSNs with a reasonable amount of energy and resource utilization. However, they still suffer from limitations in terms of flexibility, key management, authentication, and the power resource management processes. This paper addresses these issues by designing FlexCrypt, an automated lightweight cryptographic scheme for WSNs. In the FlexCrypt scheme, a new dynamic clustering technique that supports mobility among the sensor nodes is developed. Moreover, the proposed scheme introduces a flexible lightweight cryptographic method to control the complexity of the encryption by automating the selection of encryption parameters based on the presently available resources of each sensor node to encrypt the data. In addition, a new lightweight key management and authentication method is designed to establish secure communication and the exchange of data and keys among the various WSN nodes. The proposed FlexCrypt scheme was evaluated using the Cooja simulator with Contiki OS. The results prove that the proposed scheme provides a significant improvement in terms of delay and encryption time in addition to power consumption and network lifetime compared to other ciphers that use fixed encryption parameters. It can effectively extend the network lifetime by 86%, 94% and 90% compared to the FlexenTech, AES and TEA ciphers, respectively. The security analysis demonstrates that the FlexCrypt scheme can resist various attacks such as brute-force, eavesdropping, man-in-the-middle and replay attacks.

在无线传感器网络（WSN）中，由于其开放，大规模和资源受限的性质，安全性，效率和能耗仍然是主要挑战。已经开发了6LoWPAN协议和许多其他轻量级加密方法，以通过合理量的能源和资源利用来提高WSN的安全性和效率。但是，它们仍然在灵活性，密钥管理，身份验证和电源管理过程方面受到限制。本文通过设计FlexCrypt（一种用于WSN的自动轻量级加密方案）解决了这些问题。在FlexCrypt方案中，开发了一种新的动态聚类技术，该技术支持传感器节点之间的移动性。而且，所提出的方案引入了一种灵活的轻量级加密方法，该方法通过基于每个传感器节点当前可用的资源来自动选择加密参数来控制加密的复杂性，从而对数据进行加密。另外，设计了一种新的轻量级密钥管理和身份验证方法，以在各种WSN节点之间建立安全的通信以及数据和密钥的交换。提议的FlexCrypt方案是使用带有Contiki OS的Cooja模拟器进行评估的。结果证明，与使用固定加密参数的其他密码相比，所提出的方案在功耗和网络寿命方面，在延迟和加密时间方面提供了显着的改进。与FlexenTech相比，它可以有效地将网络寿命延长86％，94％和90％，分别为AES和TEA密码。安全分析表明，FlexCrypt方案可以抵抗各种攻击，例如暴力攻击，窃听，中间人攻击和重播攻击。