Secret Message Bits Research Articles

A Wireless Covert Channel Based on Constellation Shaping Modulation

Wireless covert channel is an emerging covert communication technique which conceals the very existence of secret information in wireless signal including GSM, CDMA, and LTE. The secret message bits are always modulated into artificial noise superposed with cover signal, which is then demodulated with the shared codebook at the receiver. In this paper, we first extend the traditional KS test and regularity test in covert timing channel detection into wireless covert channel, which can be used to reveal the very existence of secret data in wireless covert channel from the aspect of multiorder statistics. In order to improve the undetectability, a wireless covert channel for OFDM-based communication system based on constellation shaping modulation is proposed, which generates additional constellation points around the standard points in normal constellations. The carrier signal is then modulated with the dirty constellation and the secret message bits are represented by the selection mode of the additional constellation points; shaping modulation is employed to keep the distribution of constellation errors unchanged. Experimental results show that the proposed wireless covert channel scheme can resist various statistical detections. The communication reliability under typical interference is also proved.

Embedded FPGA Design for Optimal Pixel Adjustment Process of Image Steganography

We propose a prototype of field programmable gate array (FPGA) implementation for optimal pixel adjustment process (OPAP) algorithm of image steganography. In the proposed scheme, the cover image and the secret message are transmitted from a personal computer (PC) to an FPGA board using RS232 interface for hardware processing. We firstly embed k-bit secret message into each pixel of the cover image by the last-significant-bit (LSB) substitution method, followed by executing associated OPAP calculations to construct a stego pixel. After all pixels of the cover image have been embedded, a stego image is created and transmitted from FPGA back to the PC and stored in the PC. Moreover, we have extended the basic pixel-wise structure to a parallel structure which can fully use the hardware devices to speed up the embedding process and embed several bits of secret message at the same time. Through parallel mechanism of the hardware based design, the data hiding process can be completed in few clock cycles to produce steganography outcome. Experimental results show the effectiveness and correctness of the proposed scheme.

Boosting the Capacity of Web based Steganography by Utilizing Html Space Codes: A blind Steganography Approach

Nowadays, Web Steganography is massively used for data hiding. The development of web has expanded the interest for strategies that can guarantee data security on site page. This paper utilizes the html labels (tags) to conceal the secret message. Existing schemes i.e. elements containing other element, changing case letters, line shift, word shift, line break, and changing attributes are not robust across random space modification attacks. Also, imperceptibility of the cover text gets affected. Moreover, these approaches have low embedding capacity for data concealment due to the insertion of only two bits per segment. In this paper, proposed embedding procedure is based on insertion of different space codes in the content containing expressions of web source page. Our proposed scheme hides the secret message bits in the space between the text in html tags by concealing four bits per space; thus by, improving the hidden capacity with minimal perceptivity. Also, proposed method is more secure as secret data have come across some encryption prior to embedding. The experimental result shows that proposed scheme has high capacity by taking 5 variable size texts and comparing these with different existing approaches. Moreover, imperceptibility is also analyzed experimentally by comparing the file change size of the proposed approach with previous methods.

Use of One Time Pad Algorithm for Bit Plane Security Improvement

BPCS (Bit-Plane Complexity Segmentation) which is one of the steganography techniques that utilizes the human vision characteristics that cannot see the change in binary patterns that occur in the image. This technique performs message insertion by making a switch to a high-complexity bit-plane or noise-like regions with bits of secret messages. Bit messages that were previously stored precisely result the message extraction process to be done easily by rearranging a set of previously stored characters in noise-like region in the image. Therefore the secret message becomes easily known by others. In this research, the process of replacing bit plane with message bits is modified by utilizing One Time Pad cryptography technique which aims to increase security in bit plane. In the tests performed, the combination of One Time Pad cryptographic algorithm to the steganography technique of BPCS works well in the insertion of messages into the vessel image, although in insertion into low-dimensional images is poor. The comparison of the original image with the stegoimage looks identical and produces a good quality image with a mean value of PSNR above 30db when using a largedimensional image as the cover messages.

A novel LSB data hiding scheme with the lowest distortion

ABSTRACTThe proposed scheme groups three pixels as an embedding unit to conceal three bits of secret data in which the possible modification for each pixel is at most +1 or −1. With our new scheme, the probability of altering one pixel by adding 1 or subtracting 1 is 6/8; it is 1/8 when altering two pixels, and 1/8 when preserving pixels without any modification. In conventional algorithms, the expected number of modification per pixel (ENMPP) mostly ranges from 0.375 to 0.5 on average when the embedding capacity of each pixel is one bit of secret message. In contrast, our new scheme groups three pixels together to convey three bits of secret message. The ENMPP is reduced at least by 0.333 on average. As a result, our algorithm offers higher visual quality for the stego image. The experimented results have verified that our scheme is super to the previous algorithms.

A new transform domain steganography based on modified logistic chaotic map for color images

The art and science of hiding information by embedding messages in various type of digital media is called steganography. This method performs by replacing bits of multimedia files (such as graphics, sounds and texts) with bits of secret message. The information that embeds in the cover media can be plain text, cipher text and even images. Steganography sometimes is used when encryption is not permitted or more commonly, steganography is supplement for encryption. By using steganography, if the encrypted file is deciphered, the encrypted file may still hide information. This paper is proposed a new transform domain steganography method based on integer wavelet transform (IWT) for digital images and also it used a chaotic map. This map is a modified logistic map which it increases the key length and security of proposed method. Experimental results shows that the proposed method has high capability in hiding information in any images which used as a cover media. Visual quality of image after embedding process is desirable due to Peak Signal-to-Noise Ratio (PSNR) measures. Also the NIST, DIEHARD and ENT tests suite show the proposed chaotic map randomness and sensitivity to smallest changes.

An RGB colour image steganography scheme using overlapping block-based pixel-value differencing.

This paper presents a steganographic scheme based on the RGB colour cover image. The secret message bits are embedded into each colour pixel sequentially by the pixel-value differencing (PVD) technique. PVD basically works on two consecutive non-overlapping components; as a result, the straightforward conventional PVD technique is not applicable to embed the secret message bits into a colour pixel, since a colour pixel consists of three colour components, i.e. red, green and blue. Hence, in the proposed scheme, initially the three colour components are represented into two overlapping blocks like the combination of red and green colour components, while another one is the combination of green and blue colour components, respectively. Later, the PVD technique is employed on each block independently to embed the secret data. The two overlapping blocks are readjusted to attain the modified three colour components. The notion of overlapping blocks has improved the embedding capacity of the cover image. The scheme has been tested on a set of colour images and satisfactory results have been achieved in terms of embedding capacity and upholding the acceptable visual quality of the stego-image.

Dual image based reversible data hiding scheme using (7,4) hamming code

In this paper, we propose a new dual-image based reversible data hiding scheme through (7,4) Hamming code (RDHHC) using shared secret key. A block of seven pixels are collected from cover image and copied into two arrays then it is adjusted redundant Least Significant Bits (LSBs) using odd parity such that any error creation is encountered at the sender end and recovered at the receiver end. Before data embedding, we first complement the bit at shared secret position. After that, secret message bit is embedded by error creation caused by tamper in any suitable position except secret position and that error is detected as well as corrected at the receiver end using Hamming error correcting code. One shared secret position κ and one shared secret key ξ help to perform data embedding, data extraction and recovery of the original image. The secret data and original cover image are successfully recovered at the receiver end from dual stego image. Finally, we compare our scheme with other state-of-the-art methods and obtain reasonably better performance in terms of PSNR.

Exploiting Content Delivery Networks for covert channel communications

Content Delivery Networks (CDNs) became an important infrastructure in today’s Internet architecture. More and more content providers use CDNs to improve their service quality and reliability. However, providing better quality of service (QoS) by using CDNs could also be abused by attackers to commit network crimes. In this paper, we show that CDNs can be used as a covert communication channel to circumvent network censorships. Specifically, we propose the CDN covert channel attack, where accessing contents through different CDN nodes can form a unique pattern, which can be used in encoding secret messages. We implemented a proof-of-concept covert channel based on our proposed attack on CloudFront, a commercial CDN service provided by Amazon Web Service. We showed that our constructed covert channel can transmit messages with various lengths with an average transmission efficiency as 2.29 bits per request (i.e., each penetration request transmits 2.29 bits of secret message on average). After presenting the CDN covert channel attack, we also discuss possible countermeasures.

Cross correlation feature mining for steganalysis of hash based least significant bit substitution video steganography

Recently, video steganography has attracted researchers' attentions for its relative higher capacity than steganographic technique using image or audio as cover. Various image steganographic techniques have been proposed, such as least significant bit (LSB) substitution, LSB matching, etc. In (Dasgupta et al. in Int J Secur Priv Trust Manag 4:1---11, 2012), the authors proposed a hash based least significant bit substitution video steganography in spatial domain, and eight bits of secret message were divided into 3, 3, 2 segments and embedded into the RGB pixel values of cover frame. Besides, a hash function was used to determine the embedding locations. However, the hash function is fragile to attack and the observer can easily figure out the exact embedded positions. Moreover, the embedding of secret message significantly changes the cross correlation feature of consecutive video frames. Based on cross correlation analysis, a video steganalysis technique is proposed in this paper. Theoretical analysis and experimental results all show the effectiveness of the proposed cross correlation based video steganalysis technique.

A Review of Reversible Encrypted Data Concealment in Encrypted Images by Reserving Room approach for Data Protection System

The reversible encrypted data concealment in encrypted images is used to hide encrypted data in encrypted images for secret communication which has very high security. The project proposes the enhancement of protection system for secret data communication through encrypted data concealment in encrypted images. The image is then separated into number of blocks locally and lifting wavelet transform will be used to detect approximation and detailed coefficients. Then approximation part is encrypted using chaos encryption. After image encryption, the data hider will hide the secret data into the detailed coefficient which are reserved before encryption. The data hiding technique uses the adaptive LSB replacement algorithm for concealing the secret message bits into encrypted image. The proposed method can achieve real reversibility, that is, data extraction and image recovery are free of errors.

ILSBMR: improved LSBMR (ILSBMR) method

The Least Significant Bit Matching Revisited (LSBMR) is among the most commonly used methods on image steganography, aiming to make only smaller changes in an image. While security is considered as one of the basic evaluation criteria for steganography techniques and notably, LSBMR can be easily recognized due to its well-known structure, it is important to find a way to help improve this approach so that it might cause less variation in the image and also increase security. To this end, the current paper deploys divided blocks of the original cover image and a selection of the best layout to embed secret message bits from each block into color images by using LSBMR. The simulation results indicate that this improved method makes small changes in the image and increases its security, compared to the LSBMR technique.

A steganography embedding method based on edge identification and XOR coding

In this paper, we present a novel image steganography algorithm that combines the strengths of edge detection and XOR coding, to conceal a secret message either in the spatial domain or an Integer Wavelet Transform (IWT) based transform domain of the cover image. Edge detection enables the identification of sharp edges in the cover image that when embedding in would cause less degradation to the image quality compared to embedding in a pre-specified set of pixels that do not differentiate between sharp and smooth areas. This is motivated by the fact that the human visual system (HVS) is less sensitive to changes in sharp contrast areas compared to uniform areas of the image. The edge detection method presented here is capable of estimating the exact edge intensities for both the cover and stego images (before and after embedding the message), which is essential when extracting the message. The XOR coding, on the other hand, is a simple, yet effective, process that helps in reducing differences between the cover and stego images. In order to embed three secret message bits, the algorithm requires four bits of the cover image, but due to the coding mechanism, no more than two of the four bits will be changed when producing the stego image. The proposed method utilizes the sharpest regions of the image first and then gradually moves to the less sharp regions. Experimental results demonstrate that the proposed method has achieved better imperceptibility results than other popular steganography methods. Furthermore, when applying a textural feature steganalytic algorithm to differentiate between cover and stego images produced using various embedding rates, the proposed method maintained a good level of security compared to other steganography methods.

A High-Capacity Covering Code for Voice-Over-IP Steganography

Although steganographic transparency and embedding capacity are considered to be two conflicting objectives in the design of steganographic systems, it is possible and necessary to strike a good balance between them in Voice-over-IP steganography. In this paper, to improve steganographic transparency while maintaining relatively large embedding capacity, the authors present a (2n-1, 2n) covering code, which can hide 2n-1 bits of secret messages into 2n bits of cover messages with not more than n-bit changed. Specifically, each (2n-1)-bit secret message is first transformed into two 2n-bit candidate codewords. In embedding process, the cover message is replaced with the optimal codeword more similar with it. In this way, the embedding distortion can be largely reduced. The proposed method is evaluated by comparing with existing ones with a large number of ITU-T G.729a encoded speech samples. The experimental results show that the authors' scheme can provide good performance on both steganographic transparency and embedding capacity, and achieve better balance between the two objectives than the existing ones.

A New Method to Increase the Capacity of Audio Steganography Based on the LSB Algorithm

Audio techniques have been developed for audio streaming on the internet. Using the TCP/IP protocol, audio file can be uploaded, downloaded, and transmitted through the internet. This benefit of transmission makes the interest in using audio as cover object in steganography become much stronger. Capacity which is one of the most important properties of audio steganographic methods, evaluates the amount of possible embedding data within the audio file. A new embedding technique of audio steganography is proposed to increase the carrier medium capacity for substitution additional hidden message. With respect to the performed tests, the algorithm succeeds to increase the depth of embedding layer, without having effects on the signal transparency. The maximum number of bits without significant effect on host audio signal for LSB audio steganography is 4 LSBs. The secret message bits are hidden into variable and multiple LSBs layer in this method. Experimental results show that the use of this new technique which apply 7 LSBs for data embedding in comparison the LSB standard algorithm with 4 LSBs improve data hiding capacity of carrier audio by 35% to 55%. It can be observed from listening tests that there is no significant difference between the stego audio acquired from the novel technique and the main signal.

A multi-threshold based audio steganography scheme

Human auditory system is highly sensitive that can detect or discriminate subtle changes in an audio. The direct least significant bit (LSB) substitution scheme, often used in image steganography, cannot be effective for audio steganography to provide secrecy needed for many audio applications, because the embedded secret bits in the LSBs of the audio samples in a silent or near silent segment of an audio can produce strong hissing noise when played. In this work, governed by an error criterion, we present a multi-threshold-based scheme for audio steganography. In order to evade detection by means of any statistical or perceptual analysis of the resultant audio, the threshold values are derived from an error criterion that can be used to limit the number of bits to be embedded in an audio sample. To defend against retrieval of bits by an adversary as well as to dissipate any pattern in the resultant audio, a scheme for chaotic distribution of the secret message bits in the cover audio is also proposed. In comparison with most recently proposed schemes in literature, our proposed scheme exhibits better performance against statistical and perceptual analysis for the same embedding capacity. Our proposed scheme can be used to increase the capacity of the cover audio in a controlled manner by adjusting the error criterion.

A Novel Approach of Image Based Steganography Using Pseudorandom Sequence Generator Function and DCT Coefficients

This research paper present a novel approach of Image based steganography scheme where a pseudorandom sequence generator function is used to randomize the mapping sequence in a pseudorandom fashion. The embedding process of the secret message is done according to the pseudo-random sequence, and extraction is done using the same sequence at the other end. At the base level, 2D-DCT is used to hide the bits of secret message inside the stego image by replacing the LSBs of DCT coefficients. Since in previous paper the LSB substitution technique is already used, here in this paper the previous concept is extended and used DCT instead of LSB technique. A new text randomization algorithm (4-2 swap text randomization algorithm) is also used to modify the secret message before embedding.

Secure Crypto and ECG Steganography Based Data Communication for Wireless Body Sensor Network

The acquisition, processing and secure transmission of a patient’s physiological and physical parameters to a remote location has been done by Patient Tele monitoring System (PTS). The PTS uses the wireless channel for communication of patient’s data which is not secure as wireless channel is open for information being hacked by unauthorized person easily , where there is no patient’s privacy thereby this project proposes the improvement of protection system for secret data communication through encrypted data concealment in ECG signals. The proposed encryption technique is the chaos cryptography technique which encrypts the confidential data in to unreadable form and it is concealed in to the high frequency coefficient of the Wavelet decomposed ECG signals by the data hider. The reversible data hider technique and LSB replacement algorithm is used for concealing the secret message bits into the high frequency coefficients. In the data extraction module relevant key is used to extract the secret data and decryption keys are used to get back original information .Finally the performance of the proposed technique and existing technique is analyzed based on image, data recovery and time consumption.

Frame-bitrate-change based steganography for voice-over-IP

Steganography based on bits-modification of speech frames is a kind of commonly used method, which targets at RTP payloads and offers covert communications over voice-over-IP (VoIP). However, direct modification on frames is often independent of the inherent speech features, which may lead to great degradation of speech quality. A novel frame-bitrate-change based steganography is proposed in this work, which discovers a novel covert channel for VoIP and introduces less distortion. This method exploits the feature of multi-rate speech codecs that the practical bitrate of speech frame is identified only by speech decoder at receiving end. Based on this characteristic, two steganography strategies called bitrate downgrading (BD) and bitrate switching (BS) are provided. The first strategy substitutes high bit-rate speech frames with lower ones to embed secret message, which introduces very low distortion in practice, and much less than other bits-modification based methods with the same embedding capacity. The second one encodes secret message bits into different types of speech frames, which is an alternative choice for supplement. The two strategies are implemented and tested on our covert communication system StegVoIP. The experiment results show that our proposed method is effective and fulfills the real-time requirement of VoIP communication.

Low overhead reversible data hiding for color JPEG images

The current paper describes a new technique for embedding secret data in JPEG compressed color digital images. Emphasis is given in improving effective payload percentage over file size increase while retaining low distortion levels. The proposed technique is based on modification of non-zero quantized coefficients. In contrast to previously proposed techniques, the present one does not require the use of non-standard Huffman tables. Apart from that, no side information needs to be included in a JPEG header to assist the decoder in extracting the hidden message. The main idea behind the technique is to create zero population bins in the coefficient histogram in order to accommodate the secret message bits. Specifically, all coefficients whose absolute value is L are modified by 1 in the direction of their sign when a bit 1 is to be embedded or are not modified when a bit 0 is to be embedded. Coefficients with absolute values greater than L are also incremented by one in the direction of their sign, so that they are not confused with coefficients where embedding has occurred. At the side of the decoder, both the message bits can be extracted from coefficients with absolute values L and L+1, and the original image can be restored by shifting all coefficients with absolute value greater than L in the opposite direction of their sign. The results show significant improvement in comparison with representative state-of-the-art techniques, in terms of ratio of payload over file size increase.