Analysing current generation cryptographic techniques in securing a tamper correcting

application

Wayne Gartner

3rd September 2010

Introductions

• Wayne Gartner– Honours Student (2010)

• AsPro. Helen Ashman– Supervisor (Security Lab)

Outline of Presentation

• Abridged Background Story• Literature Review• Research Contributions• Methodologies• Results• Future Work

Background Story

• Current hash techniques can prove tampering has occurred– But can not fix the tampering

• Principle: Re-Instate tampered documents using pre-computed hashes– Implementing Binary or Quad Trees

Re-Instating Tampered Documents using pre-computed hashes

Works by breaking document into manageable pieces

Brute Force search for correct hash

Instead of looking for hash of entire document…– Look for the hash of the piece

Implementations include a character and a byte version

The Original Question

What are potential cryptographic techniques that can be implemented to secure the hash communication channel, without imposing unjustifiable overhead to the process?

Literature Summary – Tamper Correcting • Hash Trees:

– Ashman (2000); Moss & Ashman (2002); Williams & Emin Gun (2004)

• Tamper Correcting:– Hasan & Hassan (2007); Hassine

et al. (2009); Cong et al. (2008)

Literature Summary – Cryptography • Attacks:

– Giraud (2006); Ren-Junn et al. (2005); Aboud (2009)

• Implementations:– Chi-Fend et al. (2003); Liberatori et

al. (2007)

• Performance analysis:– Nadeem & Javed (2005); Yan &

Ming (2009)

Literature Summary – Cryptography • AES:

– Sanchez-Avilia & Sanchez-Reillol (2001)

• Blowfish:– Tingyuan & Teng (2009); Moussa

(2005)

• RSA:– Burnett & Paine (2001); Aboud et

al. (2008)

Literature Summary

• However, little published work has been done in:– Baselining a series of different

techniques under set variables– Comparing that data to a practical

implementation, and measuring assumed conclusions against actual results.

Research Contributions

• Test the Tamper Correcting prototype against different test criteria to determine strengths and challenges

• Baseline various different current generation cryptographic techniques under set conditions

• Merge the two streams of research, determining performance of both [Tamper correcting and cryptography] in a ‘real world’ application

Methodology

• Break testing into smaller cases– Isolate variables

• Cryptographic Technique• Key Size• Message Length• Binary or Quad Tree

• Each test runs 1,000 times– Mean, Median, High, Low,

Standard Deviation

Example Methodology

Purpose of Test: Determine performance speeds of Binary and Quad Tree implementations

Method: Run prototypes with input of the original document at the server side and the 20% tampered document on the client side.

Variables: Length of tampered document can be either 100, 1000 or 10,000 characters in length.

Constant: Document has been 20% Tampered

Results: Binary vs Quad Tree

0

200

400

600

800

1000

1200

1400

Tamper Degree

Quad Tree Binary Tree

Quad Tree 582.4512364 818.219442 948.3383437 997.3651745

Binary Tree 658.4599317 970.4891064 1094.092296 1145.247737

20% Tampered 50% Tampered 80% Tampered 100% Tampered

Results: Cryptographic Tests

Results: Cryptographic Tests

Results: Cryptographic Tests

Results: Application in action

Results: Application in action

Future Work

• Research Papers– Baselining of current generation

cryptographic techniques– Re-Instating tampered documents

using pre-computed hashes proof– Document Tampering as a

Stenographic technique

Future Work

• Performance Optimisation– Optimised performance of

sequential code– Run the code in parallel

(Distributed and Cloud computing)

• Visualisation Tool

Questions?