一种基于分段式宁符集的彩虹表明文生成方式

A Rainbow-Table Plain Generation Method based on Segmented Charset

Oechslin提出的彩虹表应用时间空间折中思想,是密码学中逆转单向函数的有效工具,但现在广泛使用的单一字符集彩虹表,在明文位数较大时,因明文空间的迅速膨胀,消耗计算资源的迅速增加,其应用遇到了瓶颈。为此,针对人为口令字符集构成特点,提出分段式字符集彩虹表明文生成方式,将取自不同字符集的不同位数明文拼接组成新的明文,可以有效地压缩明文空间,增加覆盖的最大明文位数。对取自CSDN的1000个真实口令哈希进行实验,结果表明,在原始彩虹表的基础上,使用分段式字符集彩虹表使恢复成功率提升39.1%。

TMTO（Time Memory Trade Off）-based rainbow table method, proposed by Oechslin, is a useful one-way function re- versing method in cryptography. However, the world widely used original rainbow table method, which uses a single charset, could not be applied efficiently when dealing with a long plain due to the lack of computing resource and the significant increase of plain space. In considering the character of human passwords constitution, a new plain generation method based on segmented charset is introduced, which splices the plains from different charsets and forms a new plain. This method could effectively reduce the plain space and increase the max plain length the rainbow table is able to cover. The experiment recovering 1000 hashes corresponding to plains taken from the revealed CSDN password library indicates that the rainbow-table plain generation method based on segmented charset could raise the success rate of hash recovering by 39.1% when used in combination of the original rainbow table method.