No abstract

Cloud computing dynamically provides high quality cloudbased secure services and applications over the internet. The efficient sharing of secure cloud storage services (ESC) scheme which allows the upper-level user to share the secure cloud storage services with multiple lower-level users. In hierarchical identity-based architecture, the sender needs to encrypt a file only once and store only one copy of the corresponding ciphertext in a cloud. The lower-level user needs to decrypt a file which will increase the computational overhead, because the lower-level user does not perform any partial decipherment. In this paper, we propose a Trapdoor commitment scheme that enables a lower-level user to send a short trapdoor to the cloud service provider before retrieving files. This scheme allows the CSP to participate in the partial decipherment, so as to reduce computational overhead on the users without leaking any information about the plaintext. If a lower-level user wants to retrieve a file with limited bandwidth, CPU and memory, the trapdoor which will largely helps to reduce computational power.

Cloud Computing is one of the emerging basic necessities in the IT world and has shown immense growth over the years. The applications can be run remotely using other people's servers. This is done with a simple user interface or an application format. In general, Cloud is simply the Internet which in turn is a network of remote servers. 'Pay only for what you use' is the bottom line for computing in cloud environment. The Cloud is a pool of heterogeneous resources.