Image compression and encryption based on integer wavelet transform and hybrid hyperchaotic system

Compression and encryption of images are emerging as recent topics in the area of research to improve the performance of data security. A joint lossless image compression and encryption algorithm based on Integer Wavelet Transform (IWT) and the Hybrid Hyperchaotic system is proposed to enhance the security of data transmission. Initially, IWT is used to compress the digital images and then the encryption is accomplished using the Hybrid Hyperchaotic system. A Hybrid Hyperchaotic system; Fractional Order Hyperchaotic Cellular Neural Network (FOHCNN) and Fractional Order Four-Dimensional Modified Chua’s Circuit (FOFDMCC) is used to generate the pseudorandom sequences. The pixel substitution and scrambling are realized simultaneously using Global Bit Scrambling (GBS) that improves the cipher unpredictability and efficiency. In this study, Deoxyribonucleic Acid (DNA) sequence is adopted instead of a binary operation, which provides high resistance to the cipher image against crop attack and salt-and-pepper noise. It was observed from the simulation outcome that the proposed Hybrid Hyperchaotic system with IWT demonstrated more effective performance in image compression and encryption compared with the existing models in terms of parameters such as unified averaged changed intensity, a number of changing pixels rate, and correlation coefficient.

Pengamanan Citra Dengan Kombinasi Modified Serpent IWT Dengan Modified Logistic Chaotic Map

Abstrak Algoritma kriptografi dapat digunakan untuk mengamankan citra. Salah satu algoritma kriptografi yang dapat digunakan untuk mengenkripsi citra adalah algoritma Serpent. Namun, algoritma Serpent memerlukan proses enkripsi dan dekripsi yang lama. Selain itu, pengenkripsian saja tidaklah cukup karena akan menimbulkan kecurigaan sehingga informasi akan rentan dicuri. Maka diperlukan teknik steganografi seperti metode Integer Wavelet Transform (IWT). Citra rahasia akan dienkripsi terlebih dahulu dengan menggunakan metode Modified Serpent, dimana modifikasi Serpernt mengubah proses transformasi substitusi byte (DES S-box) menjadi list bilangan prima 257 yang memiliki 128 generator untuk digunakan sebagai kunci di setiap putarannya. Pada proses penyisipan dengan metode IWT, perlu ditentukan posisi bit dan piksel pada cover image yang akan disisipkan sebuah pesan. Untuk menentukan posisi tersebut, maka digunakanlah fungsi chaos. Setelah itu, dapat dilakukan proses ekstraksi terhadap citra stego yang dihasilkan pada proses penyisipan untuk memperoleh kembali bit yang tersimpan didalamnya. Kumpulan bit tersebut dapat didekripsi sehingga akan diperoleh kembali citra rahasia semula.

An Improved ECG Steganography Using Integer Wavelet Transform and Offset Coefficient with LSB Substitution

In this work, we present an improved steganography for electrocardiogram (ECG) hosts to solve the issues of existing ECG steganographic methods, which have less hiding capacity and insufficient signal-to-noise ratio (SNR)/ peak SNR (PSNR). Based on the integer wavelet transform (IWT) domain, sensitive (or private) data such as patients’ data and personal information can be efficiently embedded in an ECG host via the IWT coefficient adjustment and the least significant bit (LSB) technique. Simulations confirmed that the SNR/ PSNR, and payload of the proposed method outperform those of existing techniques. In addition, the proposed method is capable of resisting attacks, such as cropping, Gaussian noise-addition inversion, scaling, translation, and truncation attacks from third parties (or adversaries). Due to the fast computation time, the proposed method can be employed in portable biometric devices or wearable electronics.

An Audio Steganography Based on Run Length Encoding and Integer Wavelet Transform

This paper proposes an audio steganography method based on run length encoding and integer wavelet transform which can be used to hide secret message in digital audio. The major contribution of the proposed scheme is to propose an audio steganography with high capacity, where the secret information is compressed by run length encoding. In the applicable scenario, the main purpose is to hide as more information as possible in the cover audio files. First, the secret information is chaotic scrambling, then the result of scrambling is run length encoded, and finally, the secret information is embedded into integer wavelet coefficients. The experimental results and comparison with existing technique show that by utilizing the lossless compression of run length encoding and anti-attack of wavelet domain, the proposed method has improved the capacity, good audio quality, and can achieve blind extraction while maintaining imperceptibility and strong robustness.