This is a ppt made by shrihari ,in this encryption with privacy preserving in clouds is described! It will be helpfull for those who are doing projects on cloud!

1. Attribute Based Encryption
with Privacy Preserving In
Clouds
Presented By:
Shrihari C S
1CG11IS080

2.  Introduction
 Existing System
 Secure cloud storage model
 Proposed work
 Secure Hash Algorithm
 Paillier Algorithm
 Conclusion
OVERVIEW

3. INTRODUCTION
 A new decentralized access control schema.
 Distributed access control so that only users with
valid attributes can access them.
 Support the creation, modification and reading the
data stored in the cloud

4. EXISTING SYSTEM
 The existing access control in cloud are centralized in
nature.
 This scheme uses a symmetric key approach.
 This approach does not support the authentication.

5. SECURE CLOUD STORAGE MODEL

6. PROPOSED WORK
A. Creation of KDC
Create KDC
KDC Password KDC Password
Add User

7. B. KDC Authentication
KDC User
User Registration process
Data Stored in
Database

8. C. Trustee and User Accessibility
Database
Request Token
User id
Trustee Verifying
Provide Token

9. D. Creation of access policy
Access policies
KDC
Cloud
Token
Creation of access policy
C
C

10. KDC
User Token
Public key Private key
File Download
G. File Accessing

11. File Recovery Technique
Recovery File
Corrupted File
F. File Restoration

12. F. Secure Hash Algorithm

13. H. Paillier Algorithm
Key generation
Step 1: Choose two large prime numbers p and q randomly and
independently of each other such that gcd (pq, (p-1)(q-1))=1.
This property is assured if both primes are of equal length.
Step 2: Compute n=pq and λ=lcm(p-1,q-1).
Step 3: Select random integer g where gZ*n2.
Step 4: Ensure n divides the order of g by checking the existence
of the following modular multiplicative inverse
μ= (L(gλ mod n2))-1mod n.
where function L is defined as L(u)= (u-1)/n.

14. Encryption
• Let m be a message to be encrypted where m Zn.
• Select random r where r Z*n.
• Compute cipher text as: c= ek (x; r ) = gm.rn mod n2
Decryption
• Cipher text: cZ*n2.
• Compute message: m=dk(y)= (L(yλ mod n2 ))/((L(gλ
mod n2 )) mod n.
Contd …

15. CONCLUSION
• A decentralized access control technique with anonymous
authentication.
• Provides user revocation.
• The cloud does not know the identity of the user who stores
information, but only verifies the user’s credentials.
• One limitation is that the cloud knows the access policy for
each record stored in the cloud.

16. Future Work
 In future, using SQL queries for hide the attributes and
access policy of a user.
 Files stored in cloud can be corrupted. So for this issue
using the file recovery technique to recover the corrupted
file successfully and to hide the access policy and the user
attributes

17. THANK YOU