Secure Multi-Cloud data sharing using Key Aggregate Cryptosystem for scalable data sharing.

Abstract-In Cloud Computing data sharing and security is important functionality. We describe public key encryption.efficient delegation of decryption which of stable size of cipher text is to possible. The new thing is that one can any aggregate set of secrete keys and make them compact as a single key. That can encompass the power of all keys aggregated. The new produced Aggregated Key can be send via email or mobile OTP or small memory storage device to the client. Ensuring the security of cloud computing is second major factor and dealing with because of service availability failure the “single cloud ” providers demonstrated less famous failure and possibility malicious insiders in the single cloud. A movement towards “Multi-Clouds”, In other words "Inter-Clouds " or "Cloud-Of-Clouds " as emerged recently. This works aim to reduce security risk and better flexibility and efficiency to the user