A cost-Efficient Implementation of Public-key Cryptography on Embedded Systems

The ever increasing demand for security in embedded systems such as smart cards has resulted in the need to provide cost-efficient hardware that can compute the public-key cryptography. Now, 8-bit microcontrollers still hold a considerable share of the low-cost embedded system market and dominate in the smart card industry. The performance of 8-bit microcontrollers is too inefficient to implement the necessary cryptography operations in software. In this paper we describe the feasibility of utilizing an public-key cryptographic coprocessor on an 8-bit microcontroller to get time and size trade-offs. The coprocessor flexibly supports both RSA with ranging from 256 bit to 2048 bit and ECC on GF(2257) field. In order to exploit the full potential of our coprocessor, We proposed a small direct memory access (DMA) to removing system-level performance bottlenecks caused by the transfer of data between coprocessor and external RAM. Considering performance and hardware cost, our design compares favorably with existing solutions.