Abstract
Broadcast is an efficient communication channel in wireless sensor networks (WSNs). Through authentic broadcast, deployed sensors can perform legitimate actions issued by a base station. In previous literature, broadcast authentication can be realized by symmetric or asymmetric cryptography. Ideally, a complete solution for broadcast authentication is digital signature based on asymmetric cryptography. However, asymmetric cryptography utilizes expensive operations, which result in computational bottlenecks for resource constraint sensors. Among these cryptosystems, Elliptic Curve Cryptography (ECC) seems to be the most efficient and the most popular choice in WSNs. Unfortunately, signature verification in ECC is not efficient enough. In contrast to ECC, signature verification in RSA is quite efficient, but RSA is not recommended for use on WSNs due to its large signing time and signature size. Since fast verification is an attractive property for broadcast authentication in WSNs, we wish to make RSA signature feasible to WSNs. In this dissertation, we propose two authentic broadcast schemes based on RSA in terms of BS broadcast and sensor broadcast. Unlike conventional RSA signature, the proposed schemes adopt short moduli to reduce the computation and communication cost . Meanwhile, the weakness of short moduli can be fixed with re-keying strategies. To minimize the re-keying overhead, we propose Multi-Modulus RSA generation algorithms, which can reduce communication overhead by 66% at most or reduce storage overhead to only 32 bits per key pair. Moreover, we implemented the proposed schemes on MICAz. On 512-bit moduli, each verification spends at most 0:372 seconds, competitive with other public-key cryptosystems.