Secure Elliptic Curve generation and key establishment on a 802.11 WLAN embedded device

Abstract

Elliptic Curve Cryptography (ECC) is one of the most promising alternatives to conventional public key cryptography, such as RSA and ElGamal, since it employs keys of smaller sizes for the same level of cryptographic strength. Smaller key sizes imply smaller hardware units for performing the arithmetic operations required by cryptographic protocols and, thus, ECC is an ideal candidate for implementation in embedded systems where the major computational resources (speed and storage) are limited. In this paper we present a port, written in ANSI C for maximum portability, of an open source ECC-based cryptographic library (ECC-LIB) to ATMEL's AT76C520 802.11 WLAN Access Point. One of the major features of this port, not found in similar ports, is that it supports Complex Multiplication (CM) for the construction of Elliptic Curves with good security properties. We present some experimental results that demonstrate that the port is efficient and can lead to generic embedded systems with robust ECC-based cryptographic protocols using cryptographically strong ECCs generated with CM. As an application of the ported library, an EC Diffie-Hellman key exchange protocol is developed as an alternative of the 4-way key handshake protocol of the 802.11 protocol.