In recent years, steganography has emerged as one of the main research areas in information security. Least significant bit (LSB) steganography is one of the fundamental and conventional spatial domain methods, which is capable of hiding larger secret information in a cover image without noticeable visual distortions. In this paper, a combined algorithm based on LSB steganography and chaotic encryption is proposed. Experimental results show the feasibility of the proposed method. In comparison with existing steganographic spatial domain based algorithms, the suggested algorithm is shown to have some advantages over existing ones, namely, larger key space and a higher level of security against some existing attacks.
The growing of digital communication technologies has caused a substantial increment in data transmission. When sensitive information such as bank account numbers is being shared between two communicating parties over a public channel, security of such data becomes necessary. Cryptography and steganography are two important tools for providing security and protecting sensitive information. Cryptography provides features such as confidentiality and integrity of data. For instance, confidentiality is achieved via an encryption algorithm which scrambles/mixes the private information so that it becomes unreadable to any party other than the intended recipient. However, steganography provides data security by hiding the information in a cover medium so that even the existence of a hidden message is not known to an intruder. Secret messages are embedded in cover objects to form stego objects. These stego objects are transmitted through the insecure channel. Cover objects may take the form of any digital image, audio, video and other computer files. Digital images are widely used as cover object of hidden information because of the high level of redundancy in them which is caused by the low sensitivity of the human visual system to details. The success of steganography lies in transmission of stego objects without suspicion [1]. A large number of image steganographic techniques have appeared in the literature, for example [2][3][4][5][6][7]. These techniques can be classified into two main classes: spatial domain and transform domain techniques. In spatial domain techniques, private message is embedded in the intensity of image pixels directly [2][3][4]. In transform domain techniques, the private message is embedded in the cover by modifying coefficients in a transform domain such as discrete cosine transform (DCT) and integer discrete wavelet transform [5][6].
Although transform domain based algorithms are more robust to steganalytic attacks, the spatial domain based algorithms such as least significant bit (LSB) algorithms are much simpler and faster. Several versions of the LSBs embedding algorithms have appeared in the literature. However, many steganalysis tools that reveal the insecurity of some LSBs replacement algorithms have been reported. For example, in [7] authors suggested a steganalytic attack that can estimate the length of information embedded in a host image for various LSBs algorithms. Nevertheless, the high embedding capacity and low computational complexity of these algorithms have encouraged researchers to further participate in this area.
Chaotic maps are well known for their sensitivity to initial conditions and control parameters. These properties make them suitable for building blocks in the design of many cryptographic and steganographic algorithms [3,8]. In this paper, we propose a new LSBs spatial domain algorithm that is based on mixing two 2-D chaotic maps. The proposed algorithm encrypts the secret message using mixed chaotic map and uses LSB for data hiding.
The rest of the paper is organized as follow: Section 2 presents the used 2-D chaotic maps.
In Section 3, we give a detailed description of the proposed algorithm and a flowchart. In Section 4, simulation results are presented and discussed. The conclusions are given in Section 5.
In the proposed steganography method, we have used a combination of two 2D chaotic systems which are logistic and duffing maps defined in [8,9] as given in ( 1) and (2).
where, 𝜇 , 𝜆 , 𝑥 and 𝑦 are the control parameters and state values, respectively. When 𝜇 𝑎𝑛𝑑 𝜆 𝜖 [3.57,4], the system is chaotic. The Duffing map depends on the two constants The steganographic scheme proposed in this article embeds a binary message according to the least significant bit technique as shown in Figure 1. This helps imperceptibility since the more significant bits of the cover image are not altered. Data embedded is done using the following steps: When applying LSB techniques to each byte of a 24 bit image, we can take the binary representation of the hidden data and overwrite the LSB of each byte within the cover image. If the LSB of the pixel value of cover image 𝐶(𝑖, 𝑗) is equal to the next message bit 𝑆𝑀 of secret massage to be embedded, 𝐶(𝑖, 𝑗) remain unchanged; if not, set the LSB of 𝐶(𝑖, 𝑗) to 𝑆𝑀.
In this section, experimental results are given to demonstrate the performance of the proposed algorithm. Comparative experimental studies are also presented to show the superiority of the proposed algorithm over typical existing ones. Four standard 512 × 512 × 3 colored images, namely, Airplane, Fruits, pool, and girl are used as cover images for hiding sensitive information of length 524288 bit.
Visual attacks, regarded as the simplest type of steganalysis, aim at revealing the presence of hidden information through visual inspection by the naked eye. The presented algorithm is designed to be robust against visual attacks.
For data hiding in images, hiding cap
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