This document summarizes a seminar presentation on secure data sharing for dynamic groups in multi-owner cloud environments. The presentation covered cloud computing fundamentals and challenges with identity privacy. It proposed a system called MONA that allows any group member to securely store and share encrypted data files on an untrusted cloud. Key features of MONA include dynamic group management such that new users can access previous data, anonymous yet traceable access control, and efficient user revocation. The presentation discussed the system architecture, models, modules including registration, login and file sharing, relevant algorithms, applications, advantages, and future work concerning reliability.

1. DEPARTMENT OF COMPUTER ENGINEERING
PADMABHOOSHAN VASANTDADA PATIL INSTITUTE OF TECHNOLOGY,
BAVDHAN,PUNE-411021
AY-2015-2016
A Seminar
On
“Secure Data Sharing For Dynamic Groups in Multi-Owner Using Cloud”
By
Mr. Sagar A. Dhanake
Under guidance of
Prof.V.S.Nandedkar

2. CONTENTS
.
1. Cloud Computing
2. Introduction
3. Motivation
4. Literature Survey
5. Problem Definition
6. System Architecture
7. System Models
8. Modules
9. Algorithms
10.Applications
11. Advantages
12. Conclusion
13. Future Scope
14. References

3. Cloud Computing???
.
Cloud computing is the access to computers and their functionality
via the Internet or a local area network. Users of a cloud request this
access from a set of web services that manage a pool of computing
resources.
The user cannot actually see or specify the physical location and
organization of the equipment hosting the resources they are
ultimately allowed to use. That is, the resources are drawn from a
“cloud” of resources when they are granted to a user and returned to
the cloud when they are released.
A “cloud” is a set of machines and web services that implement
cloud computing.

4. INTRODUCTION
.
Cloud computing is providing the identity privacy as one of its
obstacles without this user may not show interest to use the cloud
systems. Here unconditional identity is giving a chance to privacy
Problems.
The data owners store the encrypted data files in untrusted storage
and distribute the corresponding decryption keys only to authorized
users.
It also maintains the revocation list that gives the information
about the current group members. Changes of membership make
secure data sharing highly difficult. Key management is also become
difficult for every change of membership in the list.
To solve the above challenging issues here introduced the MONA,
Multi-owner data sharing-any one of the group member can securely
share and store the data with others by the untrusted cloud.

5. INTRODUCTION (Conti…)
Dynamic group management-This scheme is able to support
dynamic groups efficiently. Specifically, new granted users can
directly decrypt data files uploaded before their participation
without contacting with data owners.
Secure sharing and privacy preserving access control to users
is providing. So that when ever dispute occurs data owners real
identities will be revealed by group manager.
Also provide secure and privacy-preserving access control to
users, which guarantees any member in a group to anonymously
utilize the cloud resource.
It can provide strict security analysis, and perform extensive
simulations to demonstrate the efficiency of our scheme in terms
of storage and computation overhead.

6. MOTIVATION
Cloud computing is providing the basic characteristics such as
low maintenance and resource sharing.
In multiple-owner any one of the group member can share,
store or modify the data. So that all the members can enjoy the
storing and sharing of data across the cloud.
A group signature scheme allows any member of the group to
sign messages while keeping the identity secret from verifiers.
User revocation is performed by the group manager via a
public available revocation list (RL).
To transmit encrypted data to a set of users so that only a
privileged subset of users can decrypt the data.

7. LITERATURE SURVEY
SrNo Title Journal Description
1. A Dynamic
Secure Group Sharing
Framework in Public
Cloud Computing
IEEE Transactions on Cloud
Computing, vol. 2, No. 4,
Oct-Dec 2014
In this paper proposed a
dynamic secure group sharing
framework in public cloud
computing environment.
2. 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
In this paper design a secure
data sharing scheme, Mona, for
dynamic groups in an untrusted
cloud.
3 A Cloud Security
Framework for Data
Sharing in Dynamic
Gruoups
IJESR/October 2014/ Vol-
4/Issue-10/652-658.
In this paper design a secure
data sharing scheme, a user is
able to share data with others in
the group without revealing
identity privacy to the cloud.
4 Mona: Secure Multi-
Owner Data
Sharing for Dynamic
Groups in the Cloud
IJERA, January 2015 In this paper user is able to
share data with others in the
group without revealing
identity privacy to the cloud
and supports efficient user
revocation and new user
joining.

8. PROBLEM DEFINITION
Problem Statement
Secure multi-owner data sharing scheme, it implies that any user
in the group can securely share data with others by the untrusted
cloud. Support dynamic groups efficiently. Specifically, new
granted users can directly decrypt data files uploaded before
their participation without contacting with data owners.

9. SYSTEM ARCHITECTURE

10. SYSTEM MODELS
The system model consists of five different entities:-
Cloud Server
Group Manager
Group Member
Key Distribution
Revocation

11. MODULES
Registration
Login
Group Signature
File Upload
File Download
User Deletion

12. ALGORITHMS
1. Signature Generation
A group signature scheme allows any member of the group to
sign messages while keeping the identity secret from verifiers.
Besides, the designated group manager can reveal the identity of
the signature’s originator when a dispute occurs, which is
denoted as traceability.
Input: Private key (A,x), system parameter (P,U,V,H,W) and data M.
Output: Generate a valid group signature on M.
Steps:-
1. Let us consider private key (A,x) and system parameters as (P,U,V,H,W) where data is
referred as M.
2. Select random numbers , , r ,r, rx,ry,r1,r2 zq*.
3. Set 1=x and 2=x .
4. Now compute the following values as,
5. The first encryption set of values are as follows set C=f(M,T1,T2,T3,R1,R2,R3,R4,R5)
6. Now, consider another set of random numbers for further encryption process as
(C,C,Cx,C1,C2).
7. After the complete encryption process the result is =(T1,T2,T3,C,S,S,Sx,S1,S2).

13. ALGORITHMS Continue…
2. Signature Verification
Here user have to verify the group signature key and file key’s
with the triple DES decryption process.
Input: Private key (A,x), system parameter (P,U,V,H,W) and data M.
Output: Generate a valid group signature on M.
Steps:
1. Here the input parameters are (H0,H1,H2) and the group signature
=(T1,T2,T3,C,S,S,S2) and a set of revocation keys A1,....,Ar.
2. Here they set the temp file with the following set temp=e(T1,H1)e(T2,H2).
3. for i =1 to n
if e(T3-Ai,H0)=temp
4. Here if, it can get the two values are equal it returns a valid message and otherwise it
returns invalid message.

14. ALGORITHMS Continue…
3. Revocation Verification
User revocation is performed by the group manager via a
public available revocation list (RL), based on which group
members can encrypt their data files and ensure the confidentiality
against the revoked users.
Input: System parameter (P,U,V,H,W), M and a signature
Ϭ = (T1,T2,T3,c,sα,sβ,sx,sβ1,sβ2)
Output: True or False.
Steps:
1. Here the input is the encrypted form of the data which was generated in the Signature
generation process. The input parameters are System parameters(P,U,V,H,W),M and the
signature =(T1,T2,T3,C,S,S,Sx,S1,S 2).
2. Here they compute the following values.
3. After completing the generation of variables. I have to calculate the following function
f(M,T1,T2,T3,R1',R2',R3',R4',R5').
4. Here if the generated function is equals to the c (first encrypted result in encryption
process) then it returns the result as true otherwise it will show the result as false.

15. APPLICATIONS
 Data Confidentiality
 Access Control
 Anonymity and Traceability
 Efficiency
 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.

16. ADVANTAGES
Any user in the group can store and share data files with others by
the cloud.
The encryption complexity and size of cipher texts are
independent with the number of revoked users in the system.
User revocation can be achieved without updating the private keys
of the remaining users.
It provide the services as a low maintenance cost and high quality
services.
Save the investments data.
Maintain the data as a sensitive data without accessing any
unauthorized users.

17. CONCLUSION
This work designs a secure data sharing scheme, for dynamic
clusters in an untrusted cloud. A user is able to share data with
others in the group without revealing identity privacy to the cloud.
Additionally, it supports efficient user revocation and new user
joining. Moreover, the storage overhead and the encryption
computation cost are constant. Extensive analyses show that this
proposed scheme satisfies the desired security requirements and
guarantees efficiency as well.

18. FUTURE SCOPE
In future for solving the reliability and scalability issues we further
introduce the back-up group manager. In case of any failures of
group manager the back up group manager handles those problems.
So that the reliability and scalability increases.

19. REFERNCES
[1] Xuefeng Liu, Yuqing Zhang, BoyangWang, and Jingbo Yan "Mona: Secure Multi-
Owner Data Sharing for Dynamic Groups in the Cloud", IEEE TRANSACTIONS VOL.
24, NO. 6, JUNE 2013.
[2] Kaiping Xue, Member, IEEE and Peilin Hong, Member, IEEE, A Dynamic Secure
Group Sharing Framework in Public Cloud Computing IEEE Transactions on Cloud
Computing, vol. 2, No. 4, Oct-Dec 2014.
[3] K. Janardhan, M. Narendra "Mona: Secure Multi-Owner Data Sharing for Dynamic
Groups in the Cloud", International Journal of Engineering Research and Applications
(IJERA), Jan.2015.
[4] Ameena Mehar , M.S.V.V. Ramesh, D.D.D.Suribabu “A CLOUD SECURITY
FRAMEWORK FOR DATA SHARING IN DYNAMIC GROUPS”, IJESR/October
2014/ Vol-4/Issue-10/652-658.
[5] M. Kavitha Margret, Secure Policy Based Data Sharing for Dynamic Groups in the
Cloud ,IJARCET , Volume 2, Issue 6, June 2013.
[6] Hitesh S, P Ramesh Naidu "CLOUD SECURITY FRAMEWORK FOR MULTI-
OWNER DATA AUTHENTICATION", International Journal of Research In Science and
Engineering, Volume: 1 Special Issue: 2.

20. Thank You!!!!