摘要：Although Cloud Computing is a great innovation in the world of computing, there also exist downsides of cloud computing. These most important challenges are Security & Privacy of data on the cloud, check availability of data on the cloud. For these problems, Data storage security refers to the security of data on the storage media. Security is an important factor in cloud computing for ensuring clients data is placed on the secure mode in the cloud. The third party must not be stealing Data so authentication of client becomes a mandatory task. Security is very essential for applications where the sensitive data is transmitted. On the other hand, the encryption methods with minimal key size and minimal computations have to be selected as energy efficiency is also limitation of mobile applications. Therefore, there is a great need of encryption method with high levels of security and with minimal key size. Traditional Symmetric or Asymmetric encryption algorithms can be used for cloud computing to provide three cryptographic primitives, integrity, confidentiality and authentication. There are many drawbacks for Symmetric encryption algorithms such as key maintenance is a great problem faced in symmetric encryption methods and less security, level is the problem of asymmetric encryption methods even though key maintenance is easy. And there are many drawbacks of Asymmetric encryption algorithms such as those algorithms consume a significant amount of computing resources such as CPU time, memory, and battery power. There for, the main target for ensuring security is to developed new hybrid cryptography protocol. This new security protocol using combination of both symmetric and asymmetric cryptographic techniques is proposed by merging both symmetric and asymmetric techniques by a way that avoids the disadvantages of the existing hybrid protocols. We developed Five new hybrid cryptography protocol for achieving security in Mobile Cloud Computing. In proposed proto col the plain text divided into two parties, the first part is encrypted using encryption scheme and the second part encrypted using anther encryption scheme. These two schemes have occurred simultaneously so that the time required making encryption to all plain text is small because two schemes done in parallel way. We can obtain much security with a little time in this proposed protocol. The Proposed protocol has been proposed to achieve the security services such as Authentication, Confidentiality, Integrity, Non-Repudiation and Availability. The results show the superiority of NH CP algorithms over other algorithms in terms of the encryption and decryption time, processing time, and throughput
关键词：Encryption Algorithms; Cloud Security; Data Security; Information Security; Mobile cloud computing
