Lightweight cryptography (LWC) is an interesting research area in the field of information security. Some limitations like: increased components usage, time consumption, power consumption and memory requirement mandate the need for lightweight cryptography. One of the proposed algorithms in this field is Speck which was designed by the National Security Agency (NSA) in June 2013. In this paper, we propose a new ultra-lightweight cryptographic algorithm based on Speck known as Speck-R. Speck-R is a hybrid cipher, combining ARX architecture with a dynamic substitution layer. The novelty in this paper resides in adding a key-dynamic substitution layer that changes according to a dynamic key. With this modification, the number of rounds can be reduced from 26 (in Speck) to 7 (in Speck-R). Thus, the main contribution of this paper consists in reducing the execution time of Speck by at least 18% on limited devices to reach a reduction of 77% while keeping a high level of security. To backbone Speck-R’s security, different security and statistical tests are exerted on Speck-R. In addition, a real hardware implementation on three different famous IoT devices is also presented where Speck-R outperformed Speck in terms of execution times. Finally, extensive tests show that Speck-R possesses the necessary criteria to be considered as a good cipher scheme that is suitable for lightweight devices.

轻量级密码术（LWC）是信息安全领域中一个有趣的研究领域。诸如以下的一些限制：增加的组件使用量，时间消耗，功耗和内存需求迫使需要轻量级加密。国家安全局（NSA）在2013年6月设计的Speck是该领域提出的一种算法。在本文中，我们提出了一种基于Speck的超轻量密码算法Speck-R。Speck-R是一种混合密码，结合了ARX体系结构和动态替换层。本文的新颖之处在于添加了根据动态密钥而变化的密钥动态替换层。通过这种修改，弹药的数量可以从26（在Speck中）减少到7（在Speck-R中）。从而，本文的主要贡献在于，在有限的设备上，Speck的执行时间减少了至少18％，从而减少了77％，同时又保持了较高的安全性。为了支撑Speck-R的安全性，对Speck-R进行了不同的安全性和统计测试。此外，还展示了在三种不同的著名IoT设备上的实际硬件实现，其中Speck-R在执行时间方面胜过Speck。最后，大量测试表明，Speck-R具有必要的标准，可以被认为是适用于轻量级设备的良好加密方案。还展示了在三种不同的著名IoT设备上的实际硬件实现，其中Speck-R在执行时间方面胜过Speck。最后，大量测试表明，Speck-R具有必要的标准，可以被认为是适用于轻量级设备的良好加密方案。还展示了在三种不同的著名IoT设备上的实际硬件实现，其中Speck-R在执行时间方面胜过Speck。最后，大量测试表明，Speck-R具有必要的标准，可以被认为是适用于轻量级设备的良好加密方案。