Symmetrical encryption/decryption combination circuit capable of defending fault attack based on confusion mechanism

The invention relates to the technical field of password circuit implementation, in particular to a symmetric encryption/decryption combination circuit capable of defending fault attack based on a confusion mechanism, which comprises an encryption circuit unit, a decryption circuit unit, a confusion mechanism unit, a de-confusion mechanism unit and a key expansion unit, the encryption circuit unit and the decryption circuit unit are both of a fully-expanded structure and comprise Nr round transformation units. Through the random number generator unit, the memory unit and the confusion mechanism unit, filling data is not fixed, meanwhile, an induction (or injection) fault is randomized, compared with traditional single diffusion, the power consumption of the method for processing the same group of data is dynamically changed, and the data processing efficiency is improved. And meanwhile, fault information possibly existing in an encryption path is randomly diffused, and the dependency relationship between an i