Abstract—With the accelerated growth of the global requirements in digital communication and multimedia applications, the need to secure audio data has become progressively important. Digital Audio Signals (DASs) are widely used in broadcasting, voice communication, and several other applications, and they may carry sensitive or private information. For this reason, secure encryption methods are required to protect audio data, especially during propagation. In this paper, a fast and secure cryptographic method for DASs is proposed. The method uses a variable number of encryption and decryption rounds, a variable-length Private Key (PK), and variable-size audio blocking to balance security strength and computational efficiency. The proposed method employs a simple encryption-decryption function, which enhances processing speed compared to existing methods. The PK length increases as the number of rounds is increased, reaching 544 bits when four rounds are utilized, thereby providing a large key space. Test results show that when the number of rounds is increased from 1 to 4, the mean squared error increases from 0.4755 to 6.7589, whereas the peak signal-to-noise ratio and correlation coefficient values decrease from 12.6134 to 8.3193 and from 0.2010 to 0.1036, respectively. Furthermore, the encryption-decryption speed stays quite high, decreasing from 3.8499 M Samples/s to 1.1507 M Samples/s. The results confirmed that the proposed method provides acceptable reconstructed-signal quality, a good level of security, and a competitive processing speed that is less than 1 M Samples/s, making it a promising solution for secure, fast, and efficient audio transmission in modern digital systems.

Index Terms—audio encryption, chaotic logistic map, cryptography, digital audio signals, encryption speed, key space, private key, signal quality

Cite: Sara Al-Omari, Zayed Huneiti, and Ahmed Abu-Khadrah, "Digital Audio Signal Encryption Using a Chaotic Logistic Map and Variable-length Private Key," International Journal of Electrical and Electronic Engineering & Telecommunications, vol. 15, no. 5, pp. 346-356, 2026. doi: 10.18178/ijeetc.15.5.346-356

Copyright © 2026 by the authors. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).