" Moreover, they claimed that such a device can be made portable, with low power requirements, and can be built very cheaply. Such a device can be used as a stand-alone RFID skimmer, to surreptitiously read the contents of simple RFID tags. The same device can be as the ``leech'' part of a relay-attack system, by which an attacker can make purchases using a victim's RFID-enhanced credit card--despite any cryptographic protocols that may be used. "
" A German hacker ([Hes04]) used a simple PDA, equipped with an RFID read/write device, and changed product prices in a grocery shop using a software he wrote. He managed to reduce the Shampoo price from $7 to $3 and go through the cashier without incident. Supermarket checkout trials held by NCR corporation showed that some clients standing at the cashier paid for groceries held by clients standing behind them in the queue [Whi05]. "