This document summarizes a student's research report on improving data privacy for cloud computing documents. The student proposes a method using a red-black tree and partial document encryption to update encrypted documents efficiently. An experiment tests the encryption and processing times of modifying documents of different sizes using 3DES and AES algorithms. The method shows improvements over fully re-encrypting documents for small modifications. Future work aims to further optimize efficiency and develop a collaboration service.

1. Performance Improvement and Analysis for Data
Privacy of Cloud Computing Documents
指導教授：葉生正
作者：林俊淵
報告者：劉孝皇

2. Outline
• 緒論
• 文獻探討
• 研究方法
• 實驗環境與數據分析
• 結論及未來展望

3. 緒論 - Cloud Computing
• Cloud Computing Technologies, use virtualization and
automation technologies to create and popularize
computer in a variety of computing resources
• Cloud Computing Services, obtaining services from a
remote network connection
Software-as-a-Service (SaaS)
SaaS
Platform-as-a-Service (PaaS)
PaaS
Infrastructure-as-a-Service (IaaS)
IaaS

4. Cloud computing - Definition

5. Cloud Collaboration

6. Data Outsourcing
• Security issues
• Confidentiality, (data encryption and access control)
• Integrity, (hashing and CRC)

7. 研究動機

8. 研究目的
• The document which is large scale but needs to edit few
parts
• When modified, it does not have to encrypt the whole
document but only the modified parts

9. 文獻探討 (1/2)
• Cong Wang (2010), ”Privacy-Preserving Public Auditing for
Data Storage Security in Cloud Computing”, INFOCOM, pp. 1-9.

10. 文獻探討 (2/2)
• J. Hur and D. Noh, "Attribute-Based Access Control with Efficient Revocation in Data
Outsourcing Systems," IEEE Transactions on Parallel and Distributed Systems, 2010.
• Q. Liu, et al., "Efficient Sharing of Secure Cloud Storage Services," , IEEE
International Conference on Computer and Information Technology, 2010, pp. 922-
929.
• S. Ning, et al., "A privacy-preserving approach to policy-based content dissemination,"
in Data Engineering (ICDE), 2010, pp. 944-955.

11. Red-Black tree
• Red-Black tree was invented in 1972 by Rudolf Bayer. It
is a type of self-balancing binary search tree
Operation Time complexity in worse case
Search O(log n)
Insert O(log n)
Delete O(log n)
• Properties
• Every node is either red or black
• The root is black
• Every leaf is black
• If a node is red, both its children are black
• Each path from the root to a leaf contains the same number of
black nodes

12. 研究方法

13. Distribution
Access

14. Rebuilding
(p,{align:center};si:1;ei:9),(b;si:1;ei:4),
Content Stylesheet
Encryption

15. Update TreeMap ~Insertion~
Tree Node {
int : key
StringBuilder : content
}

16. Update TreeMap ~Insertion~
cont.
Step. 1
Step. 2
Step. 3
Step. 4

17. Update TreeMap ~ Remove~
Tree Node {
int : key
StringBuilder : content
}

18. Update TreeMap ~ Remove~
cont.
Step. 1
Step. 2
Step. 3
Step. 4

19. Environment
• Windows 7 64bit
• Intel Core 2 Quad CPU Q8200 @2.33Ghz
• 4.00 RAM
• Windows XP 32bit (Run on VM)
• Core 2 @2.33Ghz
• 2.00GB RAM
• Programming language : Java (JDK 1.6)

20. 3DES & AES Encryption/Decryption time

21. Document size 1MB 4MB 8MB 12MB
3DES Encrypt 187.4 618.6 1131.4 1721.8
Random Insert/Remove AES Encrypt 112.8 327.8 628 915.8

22. Processing time

23. Processing time

24. Future work
• In this study, although it pays the extra cost of establish and
maintain the red-black tree, our method is more efficient if a
large document was modified a small part
• Improve the efficiency
• 3DES is 31.04%
• AES is 23.94%
• In the future, I want to improve this study and develop a
collaboration service