1. 1 SFS: Secure File Sharing For Dynamic Groups In Cloud Shruthi Suresh M-tech CSE RCET

2. OBJECTIVE To implement an effective mechanism for sharing of data in a multi-owner manner in dynamic cloud groups while preserving data and identity privacy. 2

3. INTRODUCTION Data storage is one of the primal services offered by cloud computing. Data storage and sharing in cloud possess substantial risk to confidentiality. Challenging issues in multi-owner data sharing in dynamic groups are : – Identity privacy – Implementation of multiple-owner manner – Effect of dynamic groups Basic solution for preservation of data is to encrypt it [2]. [2] S. Kamara and K. Lauter, “Cryptographic Cloud Storage,” Proc. Int’l Conf. Financial Cryptography and Data Security (FC), pp. 136- 149, Jan. 2010. 3

4. IDENTITY PRIVACY One of the major issue in data sharing If privacy is not assured, users will be doubtful to join the cloud Another issue is unconditional identity privacy – If a member of the group deceives others, this leads to the abuse of privacy – Real user identity of betrayal should be traceable 4

5. MULTIPLE-OWNER MANNER Every member should be able to alter their own data part More flexible than single-owner manner. Single-owner manner allows only the group manager to alter data [3] – Members can only read data [3] S. Yu, C. Wang, K. Ren, and W. Lou, “Achieving Secure, Scalable, and Fine-Grained Data Access Control in Cloud Computing,” Proc. IEEE INFOCOM, pp. 534-542, 2010. 5

6. DYNAMIC GROUPS The number of users keep changing Data security is very difficult Two major issues to be addressed are : – Newly approved users must be able to get all the files shared prior to their joining without contacting data owners – After each revocation, keys of remaining members in the group need not be updated 6

7. PLUTUS: SCALABLE SECURE FILE SHARING ON UNTRUSTED STORAGE [4] Facilitates secure file sharing on untrusted servers. Protects network integrity with file-sign/file-verify keys. Files are divided into filegroups and each group is encrypted with an exclusive fileblock key Disadvantages - Heavy key distribution - After each user revocation the file-block key needs to be updated and distributed again. [4] M. Kallahalla, E. Riedel, R. Swaminathan, Q. Wang, and K. Fu, “Plutus: Scalable Secure File Sharing on Untrusted Storage,” Proc. USENIX Conf. File and Storage Technologies, pp. 29-42, 2003. 7 RELATED WORKS

8. ACHIEVING SECURE, SCALABLE, AND FINE-GRAINED DATA ACCESS CONTROL IN CLOUD COMPUTING [3] Scalable and fine-grained data access control scheme KP-ABE technique is used [9] An access structure and the corresponding secret key are assigned to authorized users by data manager Disadvantages - Single-owner manner makes it less flexible - User keys needed to be updated after each revocation [3] S. Yu, C. Wang, K. Ren, and W. Lou, “Achieving Secure, Scalable, and Fine-Grained Data Access Control in Cloud Computing,” Proc. IEEE INFOCOM, pp. 534-542, 2010. 8

9. 9 SFS: SECURE FILE SHARING FOR DYNAMIC GROUPS IN THE CLOUD

10. A secure data sharing model for dynamic groups in a remote storage Dynamic broadcast encryption is used Authentication is done by Group signatures Supports effective user repudiation and new user registration Revocation can be attained without updating the private keys of other users [1] Xuefeng Liu, Yuqing Zhang, Member, IEEE, Boyang Wang, and Jingbo Yan Xuefeng Liu, Yuqing Zhang, Member, IEEE, Boyang Wang, and Jingbo Yan, “Mona: Secure Multi- Owner Data Sharing For Dynamic Groups In The Cloud”, Ieee transactions on parallel and distributed systems, vol. 24, no. 6, june 2013. 10

11. SECURE FILE SHARING FOR DYNAMIC GROUPS IN THE CLOUD 11 System model [1] Xuefeng Liu, Yuqing Zhang, Member, IEEE, Boyang Wang, and Jingbo Yan Xuefeng Liu, Yuqing Zhang, Member, IEEE, Boyang Wang, and Jingbo Yan, “Mona: Secure Multi- Owner Data Sharing For Dynamic Groups In The Cloud”, Ieee transactions on parallel and distributed systems, vol. 24, no. 6, june 2013.

12. SECURE FILE SHARING FOR DYNAMIC GROUPS IN THE CLOUD Cloud Operated by CSPs Not fully trusted Assume cloud to be honest but curious Group manager Parameters generation User registration User revocation Tracing real identity of a dispute data owner 12

13. SECURE FILE SHARING FOR DYNAMIC GROUPS IN THE CLOUD Group members A set of registered users Group memberships keeps on changing Disadvantage Lacks reliability and scalability 13 [1] Xuefeng Liu, Yuqing Zhang, Member, IEEE, Boyang Wang, and Jingbo Yan Xuefeng Liu, Yuqing Zhang, Member, IEEE, Boyang Wang, and Jingbo Yan, “Mona: Secure Multi- Owner Data Sharing For Dynamic Groups In The Cloud”, Ieee transactions on parallel and distributed systems, vol. 24, no. 6, june 2013.

14. CONCLUSION Several techniques have been proposed to address multi-owner data sharing in dynamic clouds Identity privacy and user revocation mechanisms are to be efficiently addressed An efficient method is SFS which includes solution for the above mentioned issues 14

15. FUTURE WORK Aims at achieving reliable and scalable framework of SFS Problems to be handled are – Failure of group manager – Hanging of group manager 15

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