Audio Encryption Algorithm Based on Chen Memristor Chaotic System

Abstract

The data space for audio signals is large, the correlation is strong, and the traditional encryption algorithm cannot meet the needs of efficiency and safety. To solve this problem, an audio encryption algorithm based on Chen memristor chaotic system is proposed. The core idea of the algorithm is to encrypt the audio signal into the color image information. Most of the traditional audio encryption algorithms are transmitted in the form of noise, which makes it easy to attract the attention of attackers. In this paper, a special encryption method is used to obtain higher security. Firstly, the Fast Walsh–Hadamar Transform (FWHT) is used to compress and denoise the signal. Different from the Fast Fourier Transform (FFT) and the Discrete Cosine Transform (DCT), FWHT has good energy compression characteristics. In addition, compared with that of the triangular basis function of the Fast Fourier Transform, the rectangular basis function of the FWHT can be more effectively implemented in the digital circuit to transform the reconstructed dual-channel audio signal into the R and B layers of the digital image matrix, respectively. Furthermore, a new Chen memristor chaotic system solves the periodic window problems, such as the limited chaos range and nonuniform distribution. It can generate a mask block with high complexity and fill it into the G layer of the color image matrix to obtain a color audio image. In the next place, combining plaintext information with color audio images, interactive channel shuffling can not only weaken the correlation between adjacent samples, but also effectively resist selective plaintext attacks. Finally, the cryptographic block is used for overlapping diffusion encryption to fill the silence period of the speech signal, so as to obtain the ciphertext audio. Experimental results and comparative analysis show that the algorithm is suitable for different types of audio signals, and can resist many common cryptographic analysis attacks. Compared with that of similar audio encryption algorithms, the security index of the algorithm is better, and the efficiency of the algorithm is greatly improved.

Performance Comparison between RSA and El-Gamal Algorithms for Speech Data Encryption and Decryption

“…Segmental Spectral Signal to Noise Ratio or SSSNR is described as: (11) where 𝑋 𝑖 𝑎𝑛𝑑 𝑌 𝑖 represent the DFT of the original and encrypted speech signals, respectively [7].…”

“…Histogram is an approximate depiction of the distribution for numerical or categorical information. The speech sample values should have a roughly flat distribution after utilizing the ciphering operation in order to endure the statistical attack [11]. Figure 2 (a) depicts the input signal histogram; Figure 2 (b, c) depicts the encrypted and decrypted signal histograms after employing the RSA technology, and Figure 2 (d, e) depicts the encrypted and decrypted signal histograms after applying the El-Gamal technology.…”

“…It can be deduced from Table 3 and Figure 4 that both described systems can reduce the CC values between samples in the original signal and increase the CC values to one in the restored signal; thereby RSA and El-Gamal cryptosystems can counter this analysis successfully. These two parameters are given by [11,19]:…”

“…The suggested model is evaluated via sundry encryption/ decryption performance criteria. Chen chaotic system and fast Walsh Hadamar technology are integrated in [11] to encode the speech signal. The audio content in the method is converted into rectangular functions.…”

A Lossless Audio Encryption Method based on Chebyshev Map

“…A pseudorandom byte generator based on Ikeda chaotic map is used to encrypt audio files [8]. In another scheme, Chen memristor chaotic system is used [9]. There are also non-chaotic audio encryption methods available in the literature [10], [11].…”