Internet-of-Things (IoT) is an advanced intelligent infrastructure, which is formed by using multiple self-organizing devices. Here, the devices are utilized to examine the network and transfers the important information over internet. In this huge network, the unknown devices can create various attacks, thus the security and privacy of data is the major concerns. The major limitation in the IoT network is the devices are battery powered, so they can store low inbuilt resources. Thus, it is necessary to identify more resource optimized and security related solutions to address the problems generated in the network. In addition, the resources of the devices are consuming in higher speed due to the complex cryptography algorithms to maintain. Further, it is necessary to identify the suitable cryptography procedure for an automated IoT network along with data integrity. Therefore, this article aims to introduce the detailed survey on various cryptographic methods with their operational behavior such as asymmetric key cryptography (AKC) and symmetric key cryptography (SKC). This survey mainly focused on the cryptographic methods with respect to various attacks such as forgery and chosen-cipher text, denial of service; replay man-in-the middle, key reset, device capture and brute force attacks. Hence, the lightweight cryptography (LWC) is the prominent solution to mitigate all these attacks by using the deep learning methods and can maintain the higher security standards with the lower resource utilization in IoT environment.