Improved SM4 Encryption Algorithm Based on Mixed Congruence Method

With the increasing popularity of Android mobile terminals, the data stored in mobile terminals has become the object of attack by attackers. How to carry out effective privacy protection becomes an important issue that we need to consider. Among all privacy protection methods, it is a good strategy to encrypt data using encryption algorithms. This paper mainly studies the SM4 symmetric encryption algorithm proposed by the China National Cryptography Authority. In order to solve the crackability of the SM4 encryption algorithm, a mixed congruence method is used to generate a pseudo-random sequence, and the encrypted content is grouped and rearranged to improve its anti-cracking capability. The improved SM4 encryption algorithm is used to protect the data. Not only does the improved algorithm improve the security of the original algorithm, but also meets the need for encryption speed on Android mobile terminals.