Application of hash functions to enhance security of fast frequency hopped systems

• Main Author: Beak, Alvin Kang Qi
• Other Authors: Li Kwok Hung
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Electrical and electronic engineering::Wireless communication systems
• Online Access: https://hdl.handle.net/10356/157597
• Institution: Nanyang Technological University

With the widespread adoption of the Internet and digitalization during the Digital Era, security of wireless communications and data transmission integrity is of utmost importance. In frequency-hopped spread spectrum, the accessible channel bandwidth is divided into multiple nonoverlapping frequency slots where one or more of the available frequency slots is used to transmit the signal. At each frequency interval, the selection of frequency slots is generated by the pseudonoise (PN) sequence. The project aims to utilize hash functions to generate a more secure hopping pattern, using the properties of the hash function. The output of the PN sequence will be hashed and the resulting output will be used to select the frequency slots. 10% of the frequency bandwidth was jammed with partial-band noise jamming to test the performance of the hash function model. The results are compared against a control, a 4-stage linear feedback shift register (LFSR) to analyze the jamming probabilities with hash functions implemented. Although the jamming probabilities are constant at approximately 10% with hash functions implemented, it can be inferred that hash functions do not have adverse effects on the jamming probabilities. Hence, with the application of hash functions, it will be more difficult to decrypt the PN sequence due to its one-way property and to predict the future hopping pattern from previous patterns.