Check out the new USENIX Web site.

USENIX Home . About USENIX . Events . membership . Publications . Students
14th USENIX Security Symposium — Abstract

Pp. 1–16 of the Proceedings

Awarded Best Student Paper!

Security Analysis of a Cryptographically-Enabled RFID Device

Stephen C. Bono, Matthew Green, Adam Stubblefield, The Johns Hopkins University; Ari Juels, RSA Laboratories; Aviel D. Rubin, The Johns Hopkins University; Michael Szydlo, RSA Laboratories


We describe our success in defeating the security of an RFID device known as a Digital Signature Transponder (DST). Manufactured by Texas Instruments, DST (and variant) devices help secure millions of SpeedPassTM payment transponders and automobile ignition keys.

Our analysis of the DST involved three phases:

1 Reverse engineering: Starting from a rough published schematic, we determined the complete functional details of the cipher underpinning the challenge-response protocol in the DST. We accomplished this with only ``oracle'' or ``black-box'' access to an ordinary DST, that is, by experimental observation of responses output by the device.

2 Key cracking: The key length for the DST is only 40 bits. With an array of of sixteen FPGAs operating in parallel, we can recover a DST key in under an hour using two responses to arbitrary challenges.

3 Simulation: Given the key (and serial number) of a DST, we are able to simulate its RF output so as to spoof a reader. As validation of our results, we purchased gasoline at a service station and started an automobile using simulated DST devices.

We accomplished all of these steps using inexpensive off-the-shelf equipment, and with minimal RF expertise. This suggests that an attacker with modest resources can emulate a target DST after brief short-range scanning or long-range eavesdropping across several authentication sessions. We conclude that the cryptographic protection afforded by the DST device is relatively weak

  • View the full text of this paper in HTML and PDF.
    The Proceedings are published as a collective work, © 2005 by the USENIX Association. All Rights Reserved. Rights to individual papers remain with the author or the author's employer. Permission is granted for the noncommercial reproduction of the complete work for educational or research purposes. USENIX acknowledges all trademarks within this paper.

  • If you need the latest Adobe Acrobat Reader, you can download it from Adobe's site.
To become a USENIX Member, please see our Membership Information.

?Need help? Use our Contacts page.

Last changed: 3 Aug. 2005 ch
Technical Program
Security '05 Home