Improved Performance of Secured VoIP Via Enhanced Blowfish Encryption Algorithm by Amzari Jihadi Ghazali Submitted in accordance with the requirements for the award of the degree of Master of Philosophy of the University of Liverpool JUNE 2019 ABSTRACT Both the development and the integration of efficient network, open source technology, and Voice over Internet Protocol (VoIP) applications have been increasingly important and gained quick popularity due to new rapidly emerging IP-based network technology. Nonetheless, security and privacy concerns have emerged as issues that need to be addressed. The privacy process ensures that encryption and decryption methods protect the data from being alternate and intercept, a privacy VoIP call will contribute to private and confidential conversation purposes such as telebanking, telepsychiatry, health, safety issues and many more. Hence, this study had quantified VoIP performance and voice quality under security implementation with the technique of IPSec and the enhancement of the Blowfish encryption algorithm. In fact, the primary objective of this study is to improve the performance of Blowfish encryption algorithm. The proposed algorithm was tested with varying network topologies and a variety of audio codecs, which contributed to the impact upon VoIP network. A network testbed with seven experiments and network configurations had been set up in two labs to determine its effects on network performance. Besides, an experimental work using OPNET simulations under 54 experiments of network scenarios were compared with the network testbed for validation and verification purposes. Next, an enhanced Blowfish algorithm for VoIP services had been designed and executed throughout this research. From the stance of VoIP session and services performance, the redesign of the Blowfish algorithm displayed several significant effects that improved both the performance of VoIP network and the quality of voice. This finding indicates some available opportunities that could enhance encrypted algorithm, data privacy, and integrity; where the balance between Quality of Services (QoS) and security techniques can be applied to boost network throughput, performance, and voice quality of existing VoIP services. With that, this study had executed and contributed to a threefold aspect, which refers to the redesign of the Blowfish algorithm that could minimize computational resources. In addition, the VoIP network performance was analysed and compared in terms of end-to-end delay, jitter, packet loss, and finally, sought improvement for voice quality in VoIP services, as well as the effect of the designed enhanced Blowfish algorithm upon voice quality, which had been quantified by using a variety of voice codecs. i ACKNOWLEDGEMENTS Alhamdulillah, all praise to Allah Subhanahu Wa Ta’ala for his blessings and mercy that gave me the strength to accomplish this research. Besides, I would like to express my gratitude to my sponsor, Majlis Amanah Rakyat (MARA) or the Council of Trust for the People, an agency under the purview of the Ministry of Rural and Regional Development, as well as my employer, MARA Professional College Indera Mahkota, Kuantan, Malaysia, which hosted me and provided the necessary funding and resources required for this research work. Most importantly, I would like to thank Dr Waleed Al Nuaimy and Dr Ali Al Ataby, who acted sequentially as supervisors, as well as to Professor Majid Al Taee from Kingston University London as a visiting Professor at the Department of Electrical Engineering and Electronics, whose encouragement, guidance, and support had been helpful throughout the whole study period. Moreover, I would never forget to acknowledge the great support given by Professor Asoke Nandi, who guided me at the initial phase of my research, for his vast knowledge in the field and contributions at all levels, as well as being always available for discussion sessions. I also would love to thank all my colleagues in the research group for being there, for their unconditional support, and for the great fun we had together along these years. Many thanks go to my parents, who made many sacrifices to support me throughout the period of my professional development. Finally, I would want to thank my wife, Dr Hafizan Mat Som, my sons, Aiman Hakeemi, Ameer Amsyar, Akif Ashraf, and Afiq Zareef, who understood very well the ups and downs of research and managed to cheer me up at all times. Their dedication and support has been infinite, and I am forever grateful towards them for being always there for me. Allahuakbar. ii TABLE OF CONTENTS Abstract ............................................................................................................................. i Acknowledgements .......................................................................................................... ii Table of Contents ............................................................................................................ iii List of Abbreviations and Symbols ................................................................................ vii List of Figures ................................................................................................................ xii List of Tables ................................................................................................................. xv Chapter 1 ........................................................................................................................ 16 Introduction .................................................................................................................... 16 1.1 Background .................................................................................................... 16 1.2 Problem Statement ......................................................................................... 19 1.3 Aim and Objectives ........................................................................................ 20 1.4 Contribution ................................................................................................... 21 1.5 Thesis Outline ................................................................................................ 21 1.6 Published Work And Publication Plan .......................................................... 23 Chapter 2 ........................................................................................................................ 24 Background .................................................................................................................... 24 2.1 Voice Over Internet Protocol (VoIP) ............................................................. 24 2.1.1 VoIP Protocols ......................................................................................... 25 2.2 VoIP Traffic Metrics ...................................................................................... 31 2.3 VoIP Security Issues ..................................................................................... 34 2.3.1 VoIP Security Threats .............................................................................. 34 2.3.2 Internet Protocol Security (IPSec) ........................................................... 36 2.3.3 VoIP Encryption and algorithm ............................................................... 41 2.3.4 Blowfish Encryption Algorithm .............................................................. 44 2.4 VoIP Audio Codecs ...................................................................................... 48 2.5 VoIP Voice Quality Assessment .................................................................... 51 iii 2.5.1 Mean Opinion Score (MOS) .................................................................... 52 2.5.2 E-Model ................................................................................................... 53 2.6 Revisiting Previous Work .............................................................................. 59 2.6.1 VoIP QoS and VoIP Security .................................................................. 59 2.6.2 Voice Codecs and Voice Quality Measurement ...................................... 61 2.6.3 Enhances Blowfish Encryption Algorithm .............................................. 62 2.7 Summary ........................................................................................................ 63 Chapter 3 ........................................................................................................................ 65 Methodology .................................................................................................................. 65 3.1 Experimental and Preparation ........................................................................ 65 3.2 Encryption Algorithm Enhancement ............................................................. 69 3.3 Network Testbed Design ................................................................................ 70 3.4 Network Simulation Tools ............................................................................. 75 3.4.1 OPNET/Riverbed Simulation .................................................................. 75 3.4 Summary ....................................................................................................... 76 Chapter 4 ........................................................................................................................ 78 Blowfish Encryption Algorithm Enhancement and Implementations ..........................