The Internet of Things (IoT) has become an integral part of people’s daily lives with various applications such as smart homes, wearables, and industrial automation. However, these devices are often resource-constrained regarding computing power, memory, and energy. This makes deploying traditional cryptographic systems challenging, as they require significant computational resources and can lead to significant power consumption. To address this challenge, lightweight cryptographic systems have been developed that balance security and resource efficiency. This paper provides an overview of some of the most promising light cryptographic systems for IoT applications, including symmetric-key ciphers, hash functions, message authentication codes and public-key cryptosystems. The design principles and security properties of these systems and their practicality for IoT devices were discussed. The challenges associated with deploying lightweight cryptographic systems were also examined,mpotential solutions were proposed. Overall, this paper provides a comprehensive overview of impact of light cryptographic systems to IoT devices and its applications which aims to guide developers and researchers in selecting appropriate cryptographic keys for their IoT applications.