Provably Secure Key-Aggregate Cryptosystem With Broadcast Aggregate Key


Cloud computing is a popular area of research for inventors. And it is very important in data sharing applications. On cloud the data being shared must be secure. The flexibility and the efficiency of the data are depending upon the security parameter. To achieve purpose we define new algorithms which are depending on public key cryptography and define constant size cipher text. By using these key we can decrypt cipher text. The other encrypted files except these ciphers remain private. We can able to save this aggregate key or can send it to others for further data sharing The survey depicts some encryption schemes introduced in this data privacy for securely and efficient sharing of confidential data over a secure channel. Recently research focus on aggregation of keys of the keys in signal aggregation key which is help on load of network Data sharing being important functionality in cloud storage implement show to securely, efficiently, and flexibly share data with others.



A internet is most widely used in many applications. In that cloud computing has wide scope of area, so that the data can be uploading or download from cloud and can access easily. Large numbers of users can use data and share on cloud but present on single physical machine. But this data is not secure as user not able to control all over distributed data. The need is to share data securely among users. The assistance provider uses various authentication methods to avoid the loss and leakage of data on cloud.



The basic key-aggregate cryptosystem (KAC) in using asymmetric bilinear pairings. We prove our construction to be semantically secure against a non-adaptive adversary in the standard model under appropriate security assumptions.KAC construction requires much fewer secure channels due to its combination with broadcast encryption, that makes aggregate key distribution among multiple users more efficient and practically realizable.



Data Confidentiality: 

Unauthorized users (including the cloud service provider), should not be able to access the data at any given time. Data should remain confidential in transit, at rest and on backup media.

 User revocation: 

The data owner must be able to revoke any user’s access rights to data without affecting other authorized users in the group.

Scalability and Efficiency: 

Perhaps the biggest challenge faced by data management on the cloud is maintaining scalability and efficiency in the face of immensely large user bases and dynamically changing data usage patterns.

Collusion between entities:

 Any data sharing service in the cloud must ensure that even when certain malicious entities collude, they should still not be able to access any of the data in an unauthorized fashion.In propose structure we are using two keys to encryption and decryption data which are secret key and its aggregate key. This structure is basically design on the basis of key aggregation encryption. The data holder creates a secrete key and public structure which is public key pair. User is responsible for data encryption and he may decides cipher text block associated with the plaintext file which want to be encrypted.


The data holder provides the public structure parameter via Setup and generates a public/master-secret3 key pair via KeyGen.Encrypt is use for message encryption by any one who also decides what cipher text class is associated with the plaintext message to be encrypted .


[1] IDC Enterprise Panel. It cloud services user survey, pt. 3: Whatusers want from cloud services providers, august 2008.

[2] Sherman SM Chow, Yi-Jun He, Lucas CK Hui, and Siu Ming Yiu.Spice–simple privacy-preserving identity-management for cloud environment. In Applied Cryptography and Network Security, pages 526–543. Springer, 2012.

[3] Cong Wang, Sherman S.-M. Chow, Qian Wang, Kui Ren, and Wenjing Lou. Privacy-preserving public auditing for secure cloud storage. Cryptology ePrint Archive, Report 2009/579, 2009.

[4] Sherman SM Chow, Cheng-Kang Chu, Xinyi Huang, JianyingZhou, and Robert H Deng. Dynamic secure cloud storage with provenance. In Cryptography and Security: From Theory to Applications, pages 442–464. Springer, 2012.

[5] Erik C Shallman. Up in the air: Clarifying cloud storage protections.Intell. Prop. L. Bull., 19:49, 2014.

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