1. A new chaotic algorithm for image encryption
Authors: Haojiang Gao, Yisheng Zhang, Shuyun Liang,
Dequn Li
Source: Chaos, Solitons & Fractals, Volume 29,
Issue 2, July 2006, pp
Speaker: Chia-Hsuan Lin
Date: /7/13

2. Outline
Introduction
Proposed scheme
Experimental results
Conclusions

3. Introduction
Encryption
Decryption
Lena
encrypted image

4. Flowchart Secret key XOR and Output many times of NCA map 5 pixels
encrypted image
5 pixels of Lena

5. Logistic map

6. NCA (New Chaotic Algorithm)
tangent function
power function
Iteration property of the NCA map

7. NCA map
Satisfy
λ may be defined as
(experimental analysis)
NCA map

8. Encryption algorithm(1/2)
Block diagram of the chaotic encryption algorithm

9. Encryption algorithm(2/2)
Secret key
(x0 ,α,β)=( , 1.1, 5)
987 mod 256=219, 654 mod 256=142, 321 mod 256=65, mod 256=12, 345 mod 256=89
5 pixels
200
210
220
225
230
XOR
219
142 65 12 89
5 pixels 19 92
157
237
191

10. Experimental results(1/2)

11. Experimental results(2/2)
Encryption
Decryption with wrong key

12. Conclusions
The encryption algorithm is secure.

13. Logistic map X0
0.3 X1 X2 X3 X4 X5 X6 X7
Initial value X0 , 0< X0 <1

14. Tangent function