"Cloud storage could be a storage of information on-line in cloud that is accessible from multiple and connected resources. Cloud storage will offer smart accessibility and reliability, sturdy protection, disaster recovery, and lowest price. Cloud storage having vital practicality i.e. securely, with efficiency, flexibly sharing information with others. New public-key cryptography that is named as Key-Aggregate Cryptosystem (KAC) is introduced. Key-aggregate cryptosystem turn out constant size cipher texts specified economical delegation of decoding rights for any set of cipher text area unit attainable."