
 The processing efficiency of the widely used time-space (t-x) domain vertical seismic profiling (VSP) wavefield separation methods (such as median and singular value decomposition filtering) via one-dimensional discrete Fourier transform (DFT) depends on the wavefield separation method (or algorithm with processing parameter) and the total number of samples in the input VSP data. Once the wavefield separation method is determined, its processing efficiency is set and cannot be optimized. Although the popular frequency-wavenumber (f-k) domain VSP wavefield separation method via two-dimensional DFT has higher processing efficiency than the t-x domain VSP wavefield separation methods, its processing precision is susceptible to the spatial alias and Gibbs effects. For efficiency and precision improvements, we introduced the discrete cosine transform (DCT) operation into VSP wavefield separation for the first time, and proposed a high-efficiency and precision frequency-space (f-x) domain VSP wavefield separation method via DFT and DCT, in which the wavefield separation efficiency and precision can be optimized using the effective bandwidth cutoff frequency of the input VSP data. Based on the relationship between DFT and DCT, we combined their operations in the proposed method into one step (referred to as DCT–DFT) for further efficiency enhancement, thereby designing a high-efficiency and precision f-x domain VSP wavefield separation method via DCT–DFT. Theory analysis and synthetic and field VSP data examples show that the proposed method is highly efficient and precise, and can be widely used for three-dimensional (3D)-VSP data wavefield separation, especially for large distributed acoustic sensing (DAS)-VSP data.

High-efficiency and precision VSP wavefield separation method via DCT

Information is a vitalthing that needs to be secured and well protected during transmission between two or more parties over the internet. This can be achieved by steganography technology. Steganography is the concealing science in which the information is concealed inside other information in a way that the concealed information cannot be detectable by the human eye. Many ways are available to hide data inside a cover media for example text, image, and audio steganography, but image steganography is the most utilized technique among the others. Secure image steganography has a high-security level than traditional technique by combining steganography with cryptography due to encrypting secret information by cryptography algorithm before embedding it into the cover media by steganography algorithm. In this paper,a systematic review has been presented about secure image steganography and its renowned types. Many researchers proposed secure image steganography by using various cryptography and steganography algorithms which have been reviewed. The least significant bit ‘LSB’ was the renowned steganography algorithm which has been used by researchers due to its simplicity, while various cryptography algorithms like advanced encryption standard (AES) and blowfishhave been used to propose secure image steganography in the reviewed papers. The comparison among the reviewed papers indicated that the LSB with hash-RSA gave a greater peak signal-noise ratio ‘PSNR’ value than the others which was 74.0189 dB.

http://ijaas.iaescore.com/index.php/IJAAS/article/download/20378/12938

A systematic overview of secure image steganography

Data hiding or information hiding is a prominent class of information security that aims at reliably conveying secret data embedded in a cover object over a covert channel. Digital media such as audio, image, video, and three-dimensional (3D) media can act as cover objects to carry such secret data. Digital media security has acquired tremendous significance in recent years and will be even more important with the development and delivery of new digital media over digital communication networks. In particular, least significant bit (LSB) data hiding is easy to implement and to combine with other hiding techniques, o ff ers high embedding capacity for data, can resist steganalysis and several types of attacks, and is well suited for real-time applications. This article provides a comprehensive survey on LSB data hiding in digital media. The fundamental concepts and terminologies used in data hiding are reviewed along with a general data hiding model. The five attributes of data hiding, i.e., capacity, imperceptibility, robustness, detectability, and security, and the related performance metrics used in this survey to compare the characteristics of the di ff erent LSB data hiding methods are discussed. Given the classification of data hiding methods with respect to audio, image, video, and 3D media, a comprehensive survey of LSB data hiding for each of these four digital media is provided. In particular, landmark studies, state-of-the-art approaches, and applications of LSB data hiding are described for each of the four digital media. Their performance is compared with respect to the data hiding attributes which illustrates benefits and drawbacks of the reviewed LSB data hiding methods. The article concludes with summarizing main findings and suggesting directions for future research. This survey will be helpful for researchers and practitioners to keep abreast about the potential of LSB data hiding in digital media and to develop novel applications based on suitable performance trade-o ff s between data hiding attributes.

/pdf/lsb-data-hiding-in-digital-media-a-survey-26chelvl.pdf

LSB Data Hiding in Digital Media: A Survey

Quantum based robust and swift hybrid security mechanism

Today, huge amounts of information are transmitted over the communication networks, especially via the Internet. Therefore, many individuals are concerned with data security. Various methods were appeared to maintain data security, and the most common of these methods are cryptography. Encryption methods are exposed to many attacks, and if the attacker obtains the key, the data is decrypted, so many algorithms have emerged to hide the information within the multimedia. When the attacker gets the data, he will not suspect that this multimedia may contain other information. Data security may depend on the type of hiding algorithm used and sometimes encryption is used in conjunction with hiding to increase data security. The major aim of this work is reviewing and describing many approaches utilized for hiding data within multimedia and to create a comparison of these methods.

/pdf/subject-review-information-steganography-based-on-different-6smyzj3wct.pdf

Subject Review: Information Steganography Based on Different Methods

Cryptography and Steganography are two prominent techniques to obtain secure communication over the shared media like the Internet. Steganography is slightly ahead of cryptography because of its stealthy characteristics. In this paper, a new method has been proposed which combines cryptography and steganography to ensure even more secure communication. The Advanced Encryption Standard (AES) in spatial domain of the carrier/cover image and Least Significant Bit (LSB) replacement in the transformed domain of the same image has been used after performing a Discrete Cosine Transform (DCT) on the pixels. An additional layer of security has been introduced by applying XOR operation on the AES encrypted message with the pixel values of the carrier image. The Peak Signal to Noise Ratio (PSNR) of the proposed algorithm is better than most of the similar algorithms. With better PSNR, the proposed method depicts a three layer of security of the information and error free decryption.

/pdf/a-secure-image-steganography-using-advanced-encryption-39ukutfor6.pdf

Saima Arifin Noor

Papers

A Secure Image Steganography Using Advanced Encryption Standard and Discrete Cosine Transform