关键词: 密码, 公钥密码, 多项式, 映射, 多变量, 对称性, 投影, C^＊-体制

Abstract:

The SFLASH cryptographic scheme is a C^＊-scheme with specific parameters.It has been broken by Dubois et al with differential cryptanalytic attacks.This paper reviews the basic attacks to the SFLASH scheme,and points out that a successful attack mainly depends on the symmetry of the SFLASH scheme.Moreover,the symmetry of the C^＊-scheme is investigated,and the fact that projection can break the symmetry of the C^＊-scheme is also strictly proved.The results indicate that the SFLASH scheme with projection can effectively withstand diffe-rential attacks.

Key words: cryptography, public key cryptography, polynomials, mapping, multivariate, symmetry, projection, C^＊-scheme