The MIFARE Classic is the most widely used contactless smart card chip in the world. Its communication is based on the open ISO-14443-A standard, but the entire authentication and encryption protocols are proprietary. Several academic researchers have cracked the encryption, and even proposed attacks to recover the secret keys. However, none of their attacks have been released so far. In this project, we analyse their attack descr iptions and implement three attacks on the MIFARE Classic chip. The most critical attack recovers ANY secret key requiring wireless access to just the card only in less than five minutes on inexpensive commercial off-the-shelf hardware and without any pre-computation. Using our attacks, we expose the vulnerabilities of the Imperial College's access control system and show our ability to masquerade as any valid Imperial College personnel.