Design and Practical Implementation of a Stream Cipher Algorithm Based on a
Lorenz System
Hayder Mazin Makki Alibraheemi 1, *, , Mazen M. A. Al Ibraheemi 1, , Zainb Hassan Radhy 2,
1 Department of Electronics and Communication Engineering, Faculty of Engineering, University of Al-Qadisiyah, Iraq
2 College of Computer Science and Information Technology, University of Al-Qadisiyah, Iraq
A R T I C L E I N F O
Article history
Received 15 Aug 2024
Accepted 25 Oct 2024
Published 18 Nov 2024
Keywords
Chaos
FPGA
Hardware cosimulation
Image encryption
Lorenz attractor
A B S T R A C T
Currently, the security of data has gained significant attention in modern life. Researchers have continued
to address this issue. This work addresses image encryption in communication systems. It presents a
proposed design and implementation of a cryptography system based on the Lorenz chaos oscillator. The
paper methodology uses Xilinx System Generator (XSG) and Field Programmable Gate Array (FPGA)
technologies to implement the chaotic system. To determine the approach that uses the least amount of
FPGA resources while providing effective and efficient performance, the differential equations of the
Lorenz chaotic system are solved via the forward-Euler and Runge–Kutta integration techniques. In the
XSG environment, a secure communication system is constructed on the basis of the solution of
the differential equations. After that, the planned communication system is implemented on the FPGA
board and tested to encrypt images (coloured images). The histogram, entropy and other related security
analysis factors are calculated and analysed to test the efficiency of the designed system. Six statistical
methods were employed to provide a high level of image encryption in this work. Findings have shown
that the proposed system generates (with stable, fast and robust performance) pseudorandom bits that
can be successfully used to encrypt the data bits. The simulation and FPGA results are in good agreement;
however, the security analysis factors prove that the system can be successfully adopted for image
encryption purposes in real-time applications.

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