The document discusses Near Field Communication (NFC) technology and security issues related to NFC-based ticketing systems. It provides an overview of common NFC card standards like MIFARE Classic and Ultralight, describes vulnerabilities that have been found in their cryptographic protections. The document outlines a reference architecture for modern ticketing systems and examines security weaknesses in each component. It then introduces several tools that can be used to evaluate such systems, including the HydraNFC, Proxmark3, and NFCulT Android app created by Opposing Force. Attack techniques like lock, time and reply attacks are explained as ways to exploit NFC tickets and bypass validation mechanisms.