This project provides an implementation of the crypto1 cipher, as well as an implementation of the attack specified by the folks in Nijmegen in 2008-esorics.pdf. With this code you will be able to decrypt communications between a tag and a reader. As well as recover the SECRET KEY.
You can download it from the following link: https://packetstormsecurity.com/files/download/71119/crapto1-2.tgz
Source: https://packetstormsecurity.com/files/71119/crapto1-2.tgz.html