Internet-of-Things (IoT) is massively growing and introducing several benefits that are able to transform the world. Also, cloud computing has become significantly important due to its ability to handle large sets of data. IoT and cloud computing present a stalwart combination that can enrich several analytics and applications. Nevertheless, cloud data security and users privacy can have gaps. Especially when the IoT and cloud systems deal with a dynamically behaving users within a centralized and costly environment. Therefore, there is an urgent need for a dynamic access control scheme that considers the users’ behavior while making the access control decisions within a reasonable time. In this paper, we introduce a Multi-Dimensional Access Control (MD-AC) scheme for dynamically authorizing and revoking users in the cloud with multiple authorities. The experimental results indicate that MD-AC can evaluate access requests within reasonable and acceptable processing times. By considering very hard experimental conditions and numerous transactions, the average encryption and decryption times are 18 and 10 ms respectively. Furthermore, the proposed scheme is validated and compared with recent state-of-art schemes. The results demonstrate that the proposed scheme is fast and robust against different well-known attacks. Moreover, MD-AC can be used for keeping the privacy of IoT services over the cloud environment.

物联网（IoT）大规模增长，并引入了能够改变世界的多种好处。此外，由于云计算具有处理大量数据的能力，因此变得非常重要。物联网和云计算构成了强大的组合，可以丰富一些分析和应用程序。但是，云数据安全性和用户隐私可能存在差距。尤其是当物联网和云系统在集中且昂贵的环境中处理动态行为的用户时。因此，迫切需要一种动态访问控制方案，该方案应考虑用户的行为，同时在合理的时间内做出访问控制决策。在本文中，我们引入了多维访问控制（MD-AC）方案，用于动态授权和撤消具有多个权限的云中的用户。实验结果表明，MD-AC可以在合理且可接受的处理时间内评估访问请求。通过考虑非常艰苦的实验条件和大量事务，平均加密和解密时间分别为18 ms和10 ms。此外，对提出的方案进行了验证，并与最新的技术方案进行了比较。结果表明，该方案对不同的知名攻击具有快速，鲁棒性。此外，MD-AC可用于在云环境中保持IoT服务的隐私。通过考虑非常艰苦的实验条件和大量事务，平均加密和解密时间分别为18 ms和10 ms。此外，对提出的方案进行了验证，并将其与最新的最新方案进行了比较。结果表明，该方案针对不同的知名攻击具有快速，鲁棒的性能。此外，MD-AC可用于在云环境中保持IoT服务的隐私。通过考虑非常艰苦的实验条件和大量事务，平均加密和解密时间分别为18 ms和10 ms。此外，对提出的方案进行了验证，并与最新的技术方案进行了比较。结果表明，该方案针对不同的知名攻击具有快速，鲁棒的性能。此外，MD-AC可用于在云环境中保持IoT服务的隐私。