Abstract
RSA Cryptography is a well-known example of public key cryptographic algorithms that involves robust encryption/decryption processes. In this paper, a microcontroller based RSA is designed and proposed. Arduino Mega2560R3 microcontroller supported with external memory and a screen touch LCD as well as a double keypad has been used under the programming of C language to implement the proposed RSA coprocessor with 32 bits. It was found that the trade of between message size and the encryption time can be drawn as a liner relationship according to the block size of the encryption phase. However, such design with a MCU provided with a small solar cell (and off course with a backup battery) as well as small block sizes is considered useful for the use in wireless sensor network (WSN) applications due to the ease of connecting the MCU to the WSN which as well avoid the processing time of encryption/decryption processes that could be executed by the MCU instead of the life limited sensors. (C) 2014 Elsevier B.V.