Sharif Digital Repository

In the modern world, steganography is an image processing technique, revealing to be a suitable process for information hiding. In most cases, steganography has shown to be more effective than cryptography techniques. Recently, there have been attempts to improve the stego-image quality and hiding capacity by introducing new methods. Here, we inspect the advantages and disadvantages of some new steganography methods for digital images. The implemented methods are color and grayscale image steganography with OPVSP algorithm, BRL and GRL methods, and the simple LSB method with OPAP algorithm. Here, we compare the implementation results of these methods using MATLAB 7.4.0, with other common... 

Steganography is the art and technique of concealing secret message in ordinary data cover, transmitted over a public channel, in a way that eavesdroppers, as well as the channel users, cannot detect the presence of the secret message. However, steganalysis tries to detect this type of covert communication using some effective analysis techniques. Steganalysis is often based on statistical properties of the suspicious signal that are expected to change due to the message embedding process. Secret message (which mostly is a set of pseudo-random bits because of cryptography) affects the statistical features of the cover signal. So far, many steganalysis techniques have been reported that are... 

Blind image steganalysis is a technique used to, which require no prior information about the steganographic method applied to the stego im- age, determine whether the image contains an embedded message or not. The basic idea of blind steganalysis is to extract some features sensitive to information hiding, and then exploit classifiers for judging whether a given test image contains a secret message.The main focus of this research is to design an choose features sen-sitive to the embedding changes. In fact, we use high order moments in different domains, such as spatial, DCT and multi-resolution do-main, in order to improve the performance of existing steganalyzers.Accordingly, First, we... 

This thesis proposes new algorithms for digital watermarking that are based on Independent Component Analysis (ICA) technique. First, we will show that ICA allows the maximization of the information content and minimization of the induced distortion by decomposing the covertext (in this thesis the image) into statistically independent components. In fact, for a broad class of attacks and fixed capacity values, one can show that distortion is minimized when the message is embedded in statistically independent components. Information theoretical analysis also shows that the information hiding capacity of statistically independent components is maximal. Then we will propose a new wavelet... 

Widespread transfer of digital files over networks provides a hidden channel to transfer secret messages. Current steganalysis schemes need to work on a complete image for doing the detection job that starts when the image is entirely transferred, so are often restricted to an offline process. This restriction is serious when existence of the hidden message carriers on the network is shorter than the time required for the detection process. In this thesis, we propose a structurally fast detection method to detect the data hidden in an image passing through network. We use two of most powerful steganalysis algorithms for steganalysis of images that proposed by 1) Fridrich and Pevny and 2) Liu... 

Digital Steganography is the embedding of digital data into a video, image or audio signal. The embedding must be done such that the perceptual quality of the host signal does not seriously degrade. In the last decade, Steganography has received considerable attention in various application fields. Steganography is not always a legal process and may be used to establish illegal communications, transfer malware files to certain targets, or collect data illicitly from an organization. Steganalysis methods are developed to detect Steganography in such applications.
The purpose of this thesis is to develop a new steganalysis method based on perceptual models and statistical structure of the... 

Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity. In this thesis, we focus on entropic issue of multimedia signal in the two branches of Information hiding namely Steganography and Watermarking. How to choose the block and noise estimation in the watermarking, and analysis of the singular values decomposition in steganography are examples of using entopic issue which we use in our thesis. The two new designs for video signals AVI are presented in Watermarking. For the both proposed method ,first AVI video signal will be divided... 

Steganalysis is the science of detecting covert communication. It is called blind (universal) if designed to detect stego images steganographied by a wide range of embedding methods. In this method, statistical properties of the image are explored, regardless the embedding procedure employed. The main problem for image steganalysis is to find sensitive features and characteristics of the image which make a statistically significant difference between the clean and stego images. In this thesis we propose a blind image steganalysis method based on the singular value decomposition (SVD) of the discrete cosine transform (DCT) coefficients that are revisited in this work in order to enhance the... 

In recent years, along with development of technology and decrease in size of digital devices, copying and editing of digital multimedia products has become easier. Also, broadband technology caused simpler distribution of data. Considering above mentioned problems, we can use watermarking. Nowadays, watermarking has many applications such as secure transmission of data, owner identification, proof of ownership, authentication, broadcast monitoring etc. Watermarking is the process of hiding information in a secure host, in a way that it does not change the quality of signal. Watermarking is the science and art of hiding secret information in which neither the sender nor the receiver would... 

This thesis explored and described a new steganalysis system modeling. Image steganalysis systems are divided into two parts: feature extraction from images and classification of images. Many researches have been done in both parts and satisfactory results have also been reported. There are acceptable steganalysis methods which work accurately in high rates of steganography; however steganography in low rates is still undetectable. By lowering the rate of steganography in images, the difference between stego images and clean images would be reduced which accordingly led to the reduction of the difference between the corresponding extracted features. Thus, the ability of classification... 

The goal of this thesis is using sparse decomposition to design secure steganography algorithms to insert secret data into the different cover signals. We propose data embedding in higher semantic levels of the cover signal to reach this goal. Sparse decomposition represents a signal as a linear combination of its structural elements. Data insertion into the sparse coefficients slightly changes the effect of structural elements in the signal representation. So, quality of the stego signal is preserved and such a steganography method leads to higher imperceptibility. In addition, data insertion into the higher semantic levels leads to the higher undetectability. Steganalyzers use statistical... 

Steganalysis is the art of detecting hidden message in a cover such as an image. All steganalysis methods either are designed for a specific steganographer or are blind. Since for a stego image, the steganography method is not available, this is important to detect a stego image without any knowledge about the steganography method using which the secret image was embedded. Therefore in order to dominate all steganography method, if a given image is a stego one, we need to use voting over several steganalysis methods applied on the stego image to improve the accuracy of detection. But this approach needs a long time to process that is not practical for most steganalysis applications. We know... 

Recent developments of internet technology and digital media have led to the rapid growth of the steganography systems. Steganography is the art and science of concealing a secret message in a cover without leaving a perceptible or detectable trace of the message. Therefore, steganography methods, capable of embedding the largest possible amount of data with least distortion to the cover media, are highly demanding. The LSB steganography is a primary and simple method with high embedding capacity, where higher robustness is achieved if it is applied to the cover signal in the transform domain. However, regardless of the embedding domain, an essential robustness issue with the LSB... 

Providing security for digital information in a communication channel is a challenge in the recent years. This is due to the strength of high-speed processing resources that can threaten the security and correctness of communicating information. Using steganography method, the secret information can be hidden in an innocent media that does not attract the attention of third parties. This research discusses about steganography in images. The main goal of this research is presenting a universal steganography scheme with high steganography capacity. Using this scheme the steganographer can embed every large secret data in images securely. The reasons for selecting the subject of “Improving... 

Steganalysis is the process of discovering existence of hidden data in a file or image. Recent advances in steganographic methods result in their wide use in secure communications applications. Reports of using information hiding by criminals to send messages, and malwares to communicate to servers, emphasizes importance of steganalysis in real time applications. Due to wide use of JPEG images in social media and internet, steganalysis of JPEG images is a highly active research topic in information hiding. Number of steganographic tools available for steganography in JPEG domain, shows importance of steganalysis of this image format. Classic Steganalysis techniques combine feature... 

With the expansion of digital communications, the need for secure methods to transmit information confidentially has increased. Steganography, as one of the effective solutions, faces challenges in terms of quality, capacity, and security. This research presents novel schemes for steganography and steganalysis that utilize deep learning for embedding images into audio and detecting the audio carrier of the message. In the proposed steganography method, the image is embedded at the bit level in the frequency domain of the audio file. For this purpose, a structure with multiple paths between the layers of the network, utilizing the Inception-A network, is proposed, which improves processing and...