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 and 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 a 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. Therefore, the main target for ensuring security is to develop 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 protocols for achieving security in mobile cloud computing. In proposed protocol, the plain text is divided into two parts, the first part is encrypted using encryption scheme and the second part encrypted using another encryption scheme. These two schemes have occurred simultaneously so that the time required for making encryption to all plain texts is small because the two schemes are parallel. We can obtain much security with a little time in this proposed protocol. The proposed protocol achieves the security services such as authentication, confidentiality, integrity, non-repudiation and availability. The results show the superiority of NHCP algorithms over other algorithms in terms of the encryption and decryption times, processing time, and throughput.

encryption algorithms, cloud security, data security, information security, mobile cloud computing.