SISTEM KEAMANAN DATA MENGGUNAKAN SPREAD SPECTRUM IMAGE STEGANOGRAPHY (SSIS) DAN ALGORITMA KRIPTOGRAFI DES ( DATA SECURITY SYSTEM USING SPREAD SPECTRUM IMAGE STEGANOGRAPHY (SSIS) AND DES CRYPTOGRPHY ALGORITHM )

ABSTRAKSI: Steganography merupakan suatu teknik berkomunikasi dimana informasi disembunyikan pada media pembawa seperti citra, suara atau video tanpa memberikan perubahan yang berarti pada media tersebut. Berbeda dengan steganography yang menyembunyikan keberadaan informasi, kriptografi hanya menyembunyikan arti atau isi dari sebuah informasi. Kedua teknik ini dapat digabungkan sehingga menghasilkan informasi yang semakin sulit dilacak. Sistem yang akan dirancang ini meggunakan teknik image steganography dengan data digital yang disisipkan pada citra cover berupa teks (.txt) yang telah dienkripsi terlebih dahulu menggunakan algoritma kriptografi DES. SSIS menggunakan metode spread spectrum, dimana informasi yang akan disisipkan ke citra cover disebar ke dalam noise yang memiliki band frekuensi yang lebar. Noise inilah yang ditambahkan ke dalam citra cover. Sebagai antisipasi terjadi error selama proses transmisi, digunakan teknik Error Control Coding (ECC) yang terdiri dari enkoder konvolusi di transmitter dan dekoder yang menggunakan algoritma viterbi di receiver. Dari simulasi yang dilakukan, diketahui bahwa tingkat imperceptibility citra stego yang dihasilkan pada simulasi I (hanya untuk disimpan) tidak dipengaruhi oleh kriteria citra cover (low detail, medium detail, high detail) tapi dipengaruhi oleh jumlah bit yang disisipkan per tiap píksel citra cover. Kapasitas maksimum citra cover pada simulasi II, selain dibatasi oleh ukuran citra cover itu sendiri, juga dibatasi oleh jumlah code rate dari kode konvolusi yang digunakan dan level kuantisasi. Tingkat imperceptibility citra stego pada simulasi II dipengaruhi oleh kriteria citra cover (low detail, médium detail, high detail), ukuran file teks, dan jumlah bit yang disisipkan pada tiap piksel citra cover. Rata-rata penilai MOS dari sampel 30 orang didapatkan bahwa citra stego memiliki penilaian fine pada kanal dengan SNR diatas 22 dB.Kata Kunci : ABSTRACT: Steganography is a technique in communication system, where information is concealed into a carrier media, such us image, voice and video, without make significant changes to the cover media. Different from steganography which hiding information in plain sight, cryptography applications are used to encrypt information so that only the sender and recipient can understand it. Both of this techniques can be combined so that the information can be more difficult to breaked. This system is designed using image steganography with text file (.txt) as hiding information that was encrypted before using DES algorithm. SSIS is using spread spectrum method, where information that will be embedded into cover image is spreaded whitin noise that has wide band frequency. This noise is added then to the cover image. To anticipate an error along transmittion proccess, SSIS using Error Control Coding (ECC) with convolutional encoder in transmitter and decoder using viterbi algorithm in receiver. From this simulation I (for storage), imperceptibility level of stego image is confined by the number of embedded bit in every pixel of cover image. The image criteria is not determining imperceptibility level. In simulation II, maximum capacity determined by the size of cover image it self, code rate of convolutional encoder and level of quantization. Image criteria (low detail, medium detail, high detail), the size of text file, and the number of embedded bit in every pixel of cover image are the parameter that determine imperceptibility level of stego image in simulation II. MOS subjective values with 30 samples show that received image has high quality ( fine category ) in multipath fading+AWGN channel with SNR upper than 22 dB.Keyword

Codebook Code Division Multiple Access Image Steganography

In this paper, a new modification of spread spectrum image steganography (SSIS) is presented. The proposed modification of SSIS hides and recovers a message of substantial length within digital image while maintaining the original image size and dynamic range. An embedded message can be in the form of text, image, or any other digital signal. Our method is based on CDMA SSIS technique. To increase the information capacity of the stego channel and decrease a distortion of a cover image, a new modification of CDMA using a codebook (in the following referred to as Codebook CDMA (CCDMA)) is suggested

Digital Image Steganography Based On Integer Haar Wavelet Transform And Coefficient Difference

The development of digital information led to the demand for information security technology that protects the confidentiality of information. Digital steganography is one of such technology that able to protect the information from illegal interception due to its capability to hide the existence of the information without attracting the eavesdropper‟s attention. Among digital media, digital image is the most widely used media for steganography. Discrete Cosine Transform (DCT) is a well-known technique in digital image steganography, but the block calculation of DCT may pose artifact on the images. The disadvantages of DCT can be eliminating by the Discrete Wavelet Transform (DWT) which is more compatible with the Human Visual System (HVS). However the floating point of DWT can causes loss of information. On the other hand, Integer Wavelet Transform (IWT) is represented in finite precision numbers, which can avoid the problem of floating point precision of DWT. In this study, the messages are embedded on the wavelet coefficients of 1-level Integer Haar Wavelet Transform (IHWT) using Coefficient Difference scheme that adopted from Pixel Value Differencing (PVD). The messages are embedded on the difference value of two adjacent wavelet coefficients. Peak Signal to Noise Ration (PSNR) and Structural Similarity (SSIM) are used to measure the quality of stego image. The result shows that the proposed method has outperformed the existing method that employ IHWT and Pixel Mapping Method (PMM) in term of capacity vs. imperceptibility, as well as the maximum capacity. This is due to the high degree of Coefficient Difference that can tolerate larger modification of wavelet coefficients. Moreover, the Coefficient Difference can be applied on all coefficients instead of either significant or insignificant coefficient. These lead to the both high capacity and imperceptibility of digital image steganography system

A New Approach For Image Hiding Based On Contourlet Transform

A new image hiding method based on the contourlet transform is proposed inthis paper. This strategy is based on storing information in high frequency subbands of contourlet transform. The embedding approach is in direction that the contourlet sub-bands have the least statistical disorder. As a result, the proposed algorithm has a higher robustness against to common steganalysis approaches. In addition, the quality of stegano image has considerably improved in comparison with related state of the art methods, with the extracted secret image having an acceptable quality. Furthermore, theexperimental results show robustness respect to Gaussian noise and otherattacks such as JPEG compression.DOI:http://dx.doi.org/10.11591/ijece.v2i5.143

Understanding of mass transfer resistance for the adsorption of solute onto porous material from the modified mass transfer factor models

Mass transfer is important in separation and is essential for adsorption process. Mass transfer resistance controls the adsorption kinetic rate, but there is only limited understanding of the adsorption of a solute onto porous material from surface water. This study investigates the adsorptions of NHþ 4 and Al3+ onto granular activated carbon from surface water using the laboratory-scale plug flow column. The use of the modified mass transfer models is able to determine the resistance of mass transfer for the adsorption of one or more solutes present in surface water onto porous material. In this case study identified that the resistance of mass transfer is dependent on film mass transfer before and porous diffusion after break- through occurred. The research findings advance understanding of novel approach for investigating mass transfer resistance of solute onto porous material from waters