The exponential rise in software computing and internet technologies have broadened the horizon of cloud computing applications serving numerous purposes like business processes, healthcare, finance, socialization, etc. In the last few years the increase is security breaches and unauthorized data access has forced industry to achieve computationally efficient and robust security system. The increase in multimedia data communication over different cloud applications too demands an efficient security model, which is expected to have low computational complexity, negligible quality-compromise and higher security robustness. Major conventional security-systems like cryptography and steganography undergo high computational overhead, thus limiting their potential towards cloud-communication where each data input used to be of large size and a gigantic amount of multimedia data is shared across the network. To alleviate above stated problems and enable a potential solution, in this paper a highly robust Lightweight Feistel Structure based Substitution Permutation Crypto Model is developed for multimedia data security over uncertain cloud environment. Our proposed model applies substitution permutation crypto concept with Feistel structure which performs substitution-permutation over five rounds to achieve higher confusion and diffusion. To retain higher security with low computation, we applied merely 64-bit block cipher and equal key-size. MATLAB based simulation revealed that the proposed lightweight security model achieves better attack-resilience even maintaining low entropy, high-correlation, and satisfactory computation time for multimedia data encryption. Such robustness enables our proposed security model to be applied for real-world cloud data security.

软件计算和互联网技术的指数级增长扩大了可用于多种目的的云计算应用程序的范围，例如业务流程，医疗保健，财务，社交等。在最近几年中，由于安全漏洞和未经授权的数据访问，迫使行业必须实现计算高效且健壮的安全系统。通过不同的云应用程序进行的多媒体数据通信的增长也需要一种有效的安全模型，该模型具有较低的计算复杂度，可忽略的质量妥协和较高的安全性。主要的常规安全系统（例如密码术和隐写术）会承受较高的计算开销，因此限制了它们在云通信中的潜力，在云通信中，每个数据输入过去都是大型的，并且在网络上共享大量的多媒体数据。为了缓解上述问题并提出潜在的解决方案，本文针对不确定云环境下的多媒体数据安全性，开发了一种高度健壮的基于轻量Feistel结构的置换置换加密模型。我们提出的模型采用Feistel结构的置换置换密码学概念，该置换算法在五轮中执行置换置换，以实现更高的混淆和扩散。为了以较低的计算量保持较高的安全性，我们仅应用了64位分组密码和相等的密钥大小。基于MATLAB的仿真表明，所提出的轻量级安全模型甚至可以保持较低的熵，较高的相关性以及令人满意的多媒体数据加密计算时间，从而具有更好的抗攻击能力。这种鲁棒性使我们提出的安全模型可以应用于实际的云数据安全。