Summary: In recent years, with the rapid development of chaotic technology, many chaotic image cryptosystems based on pixel/bit-level techniques have been investigated. However, the drawbacks of a cryptosystem are as follows: (1) the security and efficiency are merely based on an investigation into standard test images and are not suitable for certain unique images in which the existence of “1s” or “0s” is significant; (2) the processing of bits requires more chaotic variables that elevate the computational complexity; (3) computational redundancy occurs when encrypting certain unique images. The first comprehensive analysis of different types of existing bit/pixel-level permutation techniques is carried out to show the inapplicability of such algorithms for popular cloud computing technology. To address the aforementioned security pitfalls of the state-of-the-art approaches and promote efficiency, an improved scrambling algorithm (ISA) and a reverse diffusion based on a dynamic keystream allocation strategy (DKAS) have been proposed. The present study adopts a spatiotemporal mixed linear-nonlinear coupling with the logistic-sine system (SMLNLC-LSS) for chaotic orbit generation. This system uses coveted cryptographic properties contrasted with the existing chaotic systems. The employed strategies such as ISA and reverse diffusion strongly enhance the relationship between the plaintext and encryption process to fortify the breaking of the proposed algorithm under known attacks. Because the ISA and DKAS mechanism share the same keystream, the efficiency of the proposed algorithm is effectively improved. Extensive security evaluation methods such as statistical, sensibility, visual-assessment, and efficiency analyses were imposed on the proposed methodology. The corresponding results accentuate the efficiency of the image cryptosystem while maintaining the superior security performance provided by the assurance of the desirable cryptographic properties.