A Fast and Secure Implementation of Sflash

Sflash is a multivariate signature scheme, and a candidate for standardisation, currently evaluated by the European call for primitives Nessie. The present paper is about the design of a highly optimized implementation of Sflash on a low-cost 8-bit smart card (without coprocessor). On top of this, we will also present a method to protect the implementation protection against power attacks such as Differential Power Analysis. Our fastest implementation of Sflash takes 59 ms on a 8051 based CPU at 10MHz. Though the security of Sflash is not as well understood as for example for RSA, Sflash is apparently the fastest signature scheme known. It is suitable to implement PKI on low-cost smart card, token or palm devices. It allows also to propose secure low-cost payment/banking