CHAPTER ONE

INTRODUCTION

1.1 background ofstudy    

          In our society today, we depend onInformation Technology (IT) and this dependency is continuously growing. Furtherexistence and successful development of society without computerizedinfrastructure is not feasible. On the other hand, due to the use of advancedinformation technologies, the society has become more and more vulnerable. Thefailure or misuse of information technology can negatively influence not only asingle organization, but can afflict a large number of people too. Therefore,information security has emerged as one of the most important requirements or preconditionsof the information age. When a message is sent across an insecure network, itis most likely to pass through a number of machines on the way [1]. Any ofthese machines is capable of reading and recording the message for further use,and this do not portray privacy [2]. In reality, people would prefer to havetheir message(s) concealed, so that they will be able to send a message thatshould be read only by the intended recipient.

The quest forprivacy has motivated researchers and system developers to adopt the techniquesof cryptography and intensive study of these two mostly used cryptographicalgorithms: Data Encryption Standard (DES) and Rivest-Shamir-Adleman (RSA),nevertheless, these algorithms have their strength and weakness which themsuitable or not to a particular information exchange.

For everysystem, there are basic priorities or requirements that the developer wants thesystem to satisfy; it might be speed of processing, security of the data, smallmemory consumption or others. And these priorities will affect the choice ofthe cryptographic algorithm. Exchange of information like real-timecommunication requires high speed of data transfer, the user of the encryptionalgorithm therefore need very good knowledge of the performance of DES and RSAunder different circumstances of large volume of data, attacks, systemresource, etc in order to achieve the objective of the system.

 According to [3], cryptography isthe art and science of protecting information from undesirable individuals byconverting it into a form not understood by un-authorized persons while it isstored and transmitted. The main goal of cryptography is keeping data securefrom unauthorized persons. This work examines the two most commonly usedcryptographic techniques: Data Encryption Standard (DES) andRivest-Shamir-Adleman (RSA), discusses their similarities, differences,advantages and  disadvantages as well asevaluating the performance of each of the algorithm and also showing which oneof the algorithm out-performs the other.