DESIGN OF CIRCUIT SYSTEM-BASED CRYPTOGRAPHY

Abstract

Cryptology is the science of secure communications, formed from the Greek words kryptós, "hidden", and lógos, "word". Cryptography is known as the science of writing in secret codes which can be achieved either by the use of software encrypter or through a hardware encrypter. There is need for increase in the requirement for portable devices which can only operate with extremely low power condition but the wireless protocol security layers used encryption algorithms which are unsuitable and insufficient for hardware implementation. This study presents the development of a pair of circuit system-based (hardware) cryptographic processor. The processor was implemented using PIC18F4550 microcontroller mounted on a Printed Circuit Board alongside other components to achieve the hardware based circuitry. The software end of the encryption and decryption algorithm was developed based on a library built into C Language Visual Studio version 2010 and the CCS C compiler for communication protocol stack. The hardware encryption in this study was achieved using the bitwise logic operations in the registers of the microcontroller and messages are streamed as serial ASCII data from the PC through the USB port to the microcontroller unit. The encryption is then performed on each byte representation of the ASCII data using a pass key embedded in the microcontroller unit. Decryption process is similar to the encryption process but in the reverse order. A comparative analysis of the encryption time for the hardware-based data encryption was made with the software-based equivalent and it was observed that the hardware based system was more reliable and performs better than the software based system.