Hash Functions Based on Block Ciphers

提出了一个基于分组密码的hash 函数体制,它的rate小于1 但却具有更高的效率,同时,这个hash 函数可以使用不安全的压缩函数进行构造,降低了对压缩函数安全性的要求.首先,在黑盒子模型下对这个新的体制的安全性进行了证明,然后给出了能够用于构造该体制的使用分组密码构造的压缩函数,最后通过实验对比发现,新hash 函数的速度比rate为1 的hash 函数快得多.实验结果表明,除了rate以外,密钥编排也是影响基于分组密码hash 函数效率的重要因素,甚至比rate影响更大.该体制只有两个密钥,不需要进行大量的密钥扩展运算,大大提高了基于分组密码hash 函数的效率,而且该体制可以使用现有的分组密码来构造.;In this paper, a hash function with lower rate but higher efficiency is proposed and it can be built oninsecure compression functions. The security of this scheme is proved under black-box model and somecompression function based on block ciphers are given to build this scheme. It is also shown that key schedule is amore important factor affecting the efficiency of a block-cipher-based hash function than rate. The new schemeonly needs 2 keys and the key schedule of it can be pre-computed. It means the new scheme need not re-schedulethe keys at every step during the iterations and its efficiency is improved.