What is a Radio-Frequency Identification (RFID) tag? In terms of appearance… Chip (IC)‏ Antenna

RFID devices take many forms

What is a Smart Label ? A paper label with RFID inside an antenna, printed, etched or stamped ... … and a chip attached to it … on a substrate e.g. a plastic foil ... 1

“Smart label” RFID tag Passive device – receives power from reader Range of up to several meters Simply calls out (unique) name and static data “74AB8” “5F8KJ3” “Evian bottle #949837428”

Capabilities of “smart label” RFID tag Little memory Static 96-bit+ identifier in current ultra-cheap tags Hundreds of bits soon Little computational power Several thousand gates (mostly for basic functionality)‏ No real cryptographic functions possible Pricing pressure may keep it this way for a while, i.e., Moore’s Law will have delayed impact

Use of RF Technology Airline Baggage Asset Tags Tracking Rental Building Access Rental & Libraries Animal Tracking Public Transport Secure Network Access For E-business & Online Services Ticketing

Use of RF Technology Parcel Services Road Toll Supply Chain Management Vehicle Access & Security Supply Chain Management Parcel Services Mobile Communications Banking & Payment

“Tree-based” Technique suggested by Molnar and Wagner named CR/MW

Challenge-response protokol

Tampering with one tag The attack consists of three phases: 1. The attacker has one tag T0 (e.g., her own) she can tamper with and thus obtain its complete secret. When the number of tags in the system is large, this does not significantly affect the results. 2. She then chooses a target tag T. She can query it as much as she wants but she cannot tamper with it. 3. Given two tags T1 and T2 such that T={T1, T2} that, we say that the attacker succeeds if she definitely knows which of T1 and T2 is T.

We consider a given level i where si1 and si2 are in the same subtree We consider a given level i where si1 and si2 are in the same subtree. Four cases must be considered:    

Ohkubo, Suzuki, and Kinoshita’s Protocol

a numerical comparison of CR, CR/MW, OSK, and OSK/AO