Abstract: Aiming at the potential safety hazard of MD5 encryption algorithm, this paper analyzed the methods of modular differential attack, birthday attack and preimage attack, and proposed the optimization algorithm for multiplication overflow of MD5 plaintext message block by focusing on the issue of detectable MD5 differential path, and used the characteristic of multiplication overflow to strengthen the confusion of the plaintext message and increase the difficult coefficient of inverse operation and the difficulty of differential path search, so as to prevent from the common attack algorithm and improve the reliability and stability. The results of the experiment showed that the improved algorithm was better than the original algorithm for anti-attack and collision capability.

Key words: MD5 algorithm