The requirements of information security at intervals a corporation have undergone major changes in last many decades. Before widespread use of information process instrumentation the safety of information felt to be valuable to a corporation was provided primarily by physical and administrative means. Cloud storage is gaining quality recently Cloud computing depends on sharing of resources to attain coherence and economies of scale just like a utility (like the electricity grid) over a

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... exploitation the cloud storage, users store their information on the cloud while not the burden of information storage and maintenance and services and high-quality applications from a shared pool of configurable computing resources Cryptography is maybe the foremost necessary side of communications security and is turning into progressively necessary as a basic building block for laptop security. As information sharing is a vital practicality in cloud storage. during this work we have a tendency to show that a way to firmly, with efficiency and flexibly share information with others in cloud storage. we have a tendency to describe new cryptosystem that turn out cipher text of constant size such decipherment rights are often appointed on them. we are able to create them compact as single key by aggregation of any set of secret key .this compact key handily sent others or are often store in an exceedingly very restricted secure storage. our scheme gives first efficient public key encryption scheme for flexible hierarchy.