In this study, a novel approach which uses combination of steganography
and cryptography for hiding information into digital images as host
media is proposed. In the process, secret data is first encrypted using the
mono-alphabetic substitution cipher method and then the encrypted secret data
is embedded inside an image using an algorithm which combines the random
patterns based on Space Filling Curves (SFC) and the optimal pair-wise LSB
matching method. We employ a modified Imperialist Competitive Algorithm
by Genetic Algorithm operations, namely Discrete Imperialist Competitive
Algorithm (DICA), to perform the optimal pair-wise LSB matching method
and find the suboptimum adjustment list. The performance of the proposed
method is compared with other methods with respect to Peak Signal to Noise
Ratio (PSNR). The PSNR value of the proposed method is higher than the
state-of-the-art methods by almost 4dB to 5dB.