关键词: Hash函数, MD5, 破译, 消息修改

Abstract: Based on the structural characteristics of the MD5 algorithm, the authors summarized the key points of deciphering the Hash function MD5: the introduction to the message differential, the control of the differential path and the satisfaction of the sufficient conditions. In the process of deciphering the MD5, three differences and the properties of the non-linear functions were introduced. The extensive form of the signed difference and the affection of the left shift rotation were applied in it. The important technique for attack of the MD5 algorithm, named technique of message modification, was cryptanalyzed in detail with an example. In general, the authors explored the key points of deciphering the MD5 algorithm form both the overall analysis and specific practice.

Key words: Hash function, MD5, attack, message modification