A real-time speech cryptography method based on ADPCM coding and chaotic map for VoIP system

Abstract

The Voice over Internet Protocol (VoIP) system is an open access mobile communication service over the Internet. It has become popular in recent years because of constant development of high-speed internet, available software and comparatively cheap method of mobile communication. VoIP communication became the new priority for its easy audio, video, image and data exchange. In the era of digitalization, VoIP is the modern digital communication system, where business, education and research came to a strong bond. Although, it sounds good in teems the matter of cost and good features but, still now it is the most unsafe communication method for high hacking rates and easy to lose important data. Even though recent software’s are becoming more intelligent for data, it requires more security in real-time environment. Safety may achieve by introducing comparatively large security method but it has to compromise the real-time environment. For VoIP system, real-time is a necessary requirement element, where most of the free software compromise with the security for real-time communication. In this research, an approximately efficient encryption structure based on chaotic maps method and Adaptive Differential Pulse Code Modulation (ADPCM) coding technique as combined algorithm is proposed, to provide real-time secure for VoIP communication, conform to ITU-T Recommendation point G.726, and ANSI T1.303 – 1989 standard’s connections 16, 24, 32 and 40 kbps for ADPCM transcoding algorithms. The chaotic map encryption has chosen for its high secure encoding with random values. ADPCM method has proposed for its transcoding energy efficiency and described small memory capable of two parallel encode functions per frame. The small memory of ADPCM holds the user define security keys. The proposed method of the encryption algorithm should have the adaptability of three main operations, 1. First, to generate chaotic values from independent initial conditions using two chaotic logistic maps, 2. The second step is to transform them into binary tables using random encoding condition and the final is 3. To execute basic proposed ADPCM process to increase more security. The simulation analysis was performed on conventional maximised data encoding speed, ITU standard single ADPCM transcoding and proposed combined method to test the packet loss ratio, delay, jitter and channel quality performance of the proposed system.