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. 393-399 Speaker: Chia-Hsuan Lin Date: 2006/7/13

Outline Introduction Proposed scheme Experimental results Conclusions

Introduction Encryption Decryption Lena encrypted image

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

Logistic map

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

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

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

Encryption algorithm(2/2) Secret key (x0 ,α,β)=(0.987654321012345, 1.1, 5) 987 mod 256=219, 654 mod 256=142, 321 mod 256=65, 012 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

Experimental results(1/2)

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

Conclusions The encryption algorithm is secure.

Logistic map X0 0.3 X1 0.839979 X2 0.537643 X3 0.996915 X4 0.012301 X5 0.048957 X6 0.095869 X7 0.346703 Initial value X0 , 0< X0 <1

Tangent function