Image Encryption and Decryption Using Combined Key Sequence of Logistic map and Lozi map

In this paper image encryption and decryption using combined key sequence of Logistic map and Lozi map is proposed. Initially discrete key sequence {K-1i}={K-11, K-12, K1(3,).. K-1n} where 'n' is size of the image and K-1i is an element of {0, 255} is generated using Logistic function. Then Lozi map is used to generate a discrete key sequence {K-2i}={K-21, K-22, K-23... K-2n} K-2i is an element of{0, 255}. Both the Key sequences are combined using XOR function to obtain single key sequence {K-i}. The obtained Key sequence {K-i} is used to encrypt the image. To study the performance of the proposed scheme a set of five different gray scale medical images are chosen. Also proposed scheme is compared with encryption scheme using key sequences generated by (i) Logistic map{K-1i} alone (ii) Lozi map {K-1i} alone. Security analysis of the scheme is analyzed using parameters such as (i) Visual analysis (ii) Histogram (iii) Correlation (iv) Entropy (v) Mean Square Error (MSE). Result shows that proposed scheme is immune to statistical attacks. Also the performances of the proposed scheme for all the five image cases are fairly same and scheme is independent of image chosen.