Cracking and repair of a college campus card amount Verification Algorithm

The primary card is a Mifare Classic card, not an original card. Its encryption is simple and all card keys are the same. You can modify the amount by using this vulnerability and consume it on campus !! You can use the mobile phone as the read key and only encrypt one sector! And very simple ~ There is no effect or secondary verification in other locations of the decryption step. It is very dangerous to directly modify the amount.

Well, this card is a good expression to the Goddess ~Solution:1. dynamic encryption 2. Complicated amount Encryption Algorithm