Study On Securely Outsourcing Multiple Modular Exponentiations In Cloud Computing

The development of virtualization technology, distributed storage, broadband Internet access, processors technology, automated management and fast, inexpensive servers have all combined to make cloud computing a compelling paradigm. Cloud computing, the long-standing vision of computing as a utility, enables convenient and on-demand network access to a centralized pool of configurable computing resources. One of the most attractive benefits of the cloud computing is the so-called outsourcing paradigm, where the resource-constraint devices can outsource their large computation workloads to the cloud servers in a pay-per-use manner. This vast process power is usually got with a distributed, large-scale server cluster and server virtualization software. Cloud computing is about moving services, computation and/or data, for cost and business advantage, off-site to an internal or external, location-transparent, centralized facility or contractor. By making data available in the cloud, it can be more easily and ubiquitously accessed, often at much lower cost, increasing its value by enabling opportunities for enhanced collaboration, integration, and analysis on a shared common platform. However, cloud computing and web services run on a network structure so they are open to network type of attacks. For the purpose of information security such as confidentiality, integrity, availability and controllability etc., outsourcing algorithms are widely used in cloud computing. This paper studys the securely outsourcing the mutiple modular exponentiations in cloud computation systematicly and the main points are as follows:1.The paper studied the existing modular exponentiation-based outsourcing schemes at home and abroad. We analyse three secure outsourcing schemes using one untrusted cloud server model, which can enable user to securely outsource exponentiations to single cloud server. The first one is a secure outsourcing scheme for fixed base-variable exponent modular exponentiations, the second is for variable base-variable exponent modular exponentiations, and the third is a secure outsourcing scheme for simultaneous modular exponentiations. The paper summarizes the disadvantages of the existing schemes and makes some improvemets.2.The paper then proposes an improved multiple modular exponentiations in secure outsourcing scheme based in the one-malicious version of two untrusted program model(i.e., “one-malicious model” for the simplicity). By the research of secrue outsourcing modular exponentiations, the scheme that this paper proposed improves the three schemes mentioned above. By invoking new subroutine, the original scheme wsa entended by the scheme that this paper proposed, which can not only achieve efficiency and secrecy in encryption and decryption but checkability and security in outsourcing schemes.3.Against the security definitions for modular exponentiations, through rigorous sercrity analysis, this paper proves that the algorithm for mutiple modular exponentiations is secure under different types of inputs.