This book is a self-sufficient text for RC5 encryption algorithm. The main content of this book are the basic of cryptography which required for RC5 algorithm and the working of present RC5 algorithm. The main motive behind writing of this book is to enhance the performance of RC5 algorithm by choosing the proper number of rounds and the result is if the number of rounds selected as a prime number then the RC5 algorithm gives better performance as compare to neighborhood numbers. The method used to explain the concept in this book is non-mathematical, graphical and tabular form. So the results are easily understandable to the reader, and even for those, who are newer to the field of cryptography. HARSIMRANJIT GILL is an Assistant Professor in Dept. of electronic and communication engineering(ECE) at PTU Jalandhar(Punjab), INDIA. He is graduate and postgraduate in ECE from PTU Jalandhar. AJMER SINGH is an Assistant Professor in ECE at Dr B R Ambedkar NIT, Jalandhar(Punjab), INDIA.He is graduate and postgraduate in ECE from the Lovely Professional University, Phagwara(Punjab), INDIA. He has valuable experience as Assistant Professor in different engineering colleges/universities