Abstract
Steganography is a widely-used technique for digital data hiding. Image steganography is the most popular among all other kinds of steganography. In this article, a novel key-based blind method for RGB image steganography where multiple images can be hidden simultaneously is described. The proposed method is based on Discrete Cosine Transformation (DCT) and Discrete Wavelet Transformation (DWT) which provides enhanced security as well as improve the quality of the stego. Here, the cover image has been taken as RGB although the method can be implemented on grayscale images as well. The fundamental concept of visual cryptography has been utilized here in order to increase the capacity to a great extent. To make the method more robust and imperceptible, pseudo-random number sequence and a correlation coefficient have been used for embedding and the extraction of the secrets, respectively. The robustness of the method is tested against steganalysis attacks such as crop, rotate, resize, noise addition, and histogram equalization. The method has been applied on multiple sets of images and the quality of the resultant images have been analyzed through various matrices namely ‘Peak Signal to Noise Ratio,' ‘Structural Similarity index,' ‘Structural Content,' and ‘Maximum Difference.' The results obtained are very promising and have been compared with existing methods to prove its efficiency.
Highlights
To find the meaning of Steganography, one has to reveal the Greek words – ‘steganos’ which means “concealed, covered or protected” and ‘graphein’ which means “writing”
The proposed method is based on Discrete Cosine Transformation (DCT) and Discrete Wavelet Transformation (DWT) which provides enhanced security as well as improve the quality of the stego
That is why this paper proposes a method where both DCT and DWT has been used which results in better quality of the image
Summary
To find the meaning of Steganography, one has to reveal the Greek words – ‘steganos’ which means “concealed, covered or protected” and ‘graphein’ which means “writing”. Steganography is the ancient art of concealing classified information into a cover object. The cover can be of the same format of the secret or of some other media. Whereas Cryptography is the science of encrypting the secret in such a way that to make it readable the recipient has to decrypt the secret with a proper key. The main advantage of steganography over cryptography is that the presence of secret is unknown to everyone except the intended recipient and it avoids the unnecessary attention as an object of being scrutinized despite of how secure the algorithm is. The main objectives of steganography can be summarized as follows:
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