Cloud computing is a fastest growing technology. It allows business organizations to use or access different applications, store information without access their personal files. While considering the power, stability and the security of cloud one can't ignore different threats to user's data on cloud storage. File access assure in real technique to the file protection due to untrusted cloud servers. In cloud storage system file entrance mechanism is more challenging issue. This system in consequence produces redundant copies of similar files or involves a completely reliable cloud server. Attacks from adversary user are difficult to stop in cloud storage.