Security Analysis and Optimization Methods of LSFR Generating Function for MIFARE Classic CARD

MIFARE CLASSIC CARD (hereinafter referred to as Mifare Classic) produced by NXP is the most common contactless smartcard on the market. Mifare Classics uses NXP's licensed patent stream cipher algorithm, CRYPTO-1, whose internal structure and algorithm parameters are commercial secrets and unknown to the outside world. At present, there is much research on the security of Mifare Classics. We analyze the security of the CRYPTO-1 algorithm in the Mifare Classics from the point of generating function of the linear feedback shift register (Linear feedback shift register, hereinafter referred to as LFSR) of the card and propose an optimization method for the vulnerability of generating function to improve the security of the Mifare Classics. Furthermore, the optimization method is generally applicable to the encryption algorithm based on the LFSR generating of pseudo-random sequences.