摘要
本文试图通过对MD5算法强度的分析,结合现有的碰撞分析的结论,为Hash算法的改进提出相应的思路。作为一个广为使用的Hash算法的MD5,一次循环包含了四轮64步及一次累加运算。本文通过对它由步到轮,再由轮到全局循环的分析,给出了现有碰撞分析的突破点及怎样弥补这些已被突破的缺陷。在现有研究的基础上,本文主要改进了文献[1]中给出的各步分析的结论;利用改进的结论将文献[1]中给出的概率分析非概率化;在全局碰撞的分析中给出了单轮的最大k-原像攻击的可能性;在文章的最后给出了Hash函数的四个可能的改进方向及相应的意见。
Analyzing the resistibility of the MD5 algorithm, this paper tries to give some advice and prediction on how to improve Hash functions.As a widely used Hash function, an iteration of the MD5 algorithm includes 4 rounds, 64 steps and one addition.Through the analyses from steps to rounds, and from rounds to iterations, the authors give the break points of recent research and how to overcome them. Based on the recent research in the Hash world, the authors ameliorate the conclusions of reference 1,make the probability analysis of reference 1confirmable with the ameliorated conclusions,give the biggest k of the k-preimage attack of Wang-like collisions,and give four directions and advice on how to improve Hash functions at the end of this paper.
出处
《计算机工程与科学》
CSCD
2007年第1期45-48,共4页
Computer Engineering & Science
关键词
MD5
强度分析
哈希函数
碰撞
MD5
resistibility analysis
Hash function
collision
