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The Blocker Tag: Selective Blocking of RFID Tags for Consumer Privacy

The Blocker Tag: Selective Blocking of RFID Tags for Consumer Privacy. Ari Juels, Ronald Rivest, and Michael Szydlo ACM CCS, October 2003 Presented by Himanshu Pagey CDA 6938 04/03/2007. Content of this presentation has been adapted/taken from RSA Labs presentation slides for this paper

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The Blocker Tag: Selective Blocking of RFID Tags for Consumer Privacy

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  1. The Blocker Tag:Selective Blocking of RFID Tags forConsumer Privacy Ari Juels, Ronald Rivest, and Michael Szydlo ACM CCS, October 2003 Presented by Himanshu Pagey CDA 6938 04/03/2007

  2. Content of this presentation has been adapted/taken from RSA Labs presentation slides for this paper http://www.rsa.com/rsalabs/staff/bios/ajuels/publications/blocker/blocker.pdf

  3. RFID Grand Vision : Next Generation Bar Codes • Line of sight • Identifies a product. • Radio Contact ( Fast automated scanning) • Uniquely identifies a product ( Provides a pointer to an entry in database)

  4. Constraints / Privacy Concerns • Few Thousand Gates • No Cryptographic function available. • Static read / Write functions

  5. Commercial Applications • Supply Chain – Inventory tracking • Anti – counterfeiting • Parenting logistics (RFID bracelets for children in water park) • Maintaining shelf stocks in retail environment • Gillette Mach 3 Razor blades • Product Recalls

  6. Reference: http://www.rsa.com/rsalabs/staff/bios/ajuels/publications/blocker/blocker.pdf

  7. Approach 1: “Faradays Cage” Reference: http://www.rsa.com/rsalabs/staff/bios/ajuels/publications/blocker/blocker.pdf

  8. Approach 2 “Kill Tags” Reference: http://www.rsa.com/rsalabs/staff/bios/ajuels/publications/blocker/blocker.pdf

  9. Usefulness of RFID tags • Product Return • Physical Access Control • Theft Protection • Intelligent microwaves For the success of these applications the RFID tags cannot be killed.

  10. Smart Applications • Smart Microwaves . Ovens that know how to cook pre-packaged food items. • Smart Refrigerator that can recognize expired items and create shopping lists. • Closets that can tally the contents. • Airline tickets that indicate your location in the airport • “Function Creep” – many more uses “unimagined” or “unimaginable”

  11. Consumer Backlash • Walmart “Smart” shelf project cancelled. • Benetton RFID plans withdrawn • Campaigns against RFID usage • NoCards.org • BoycottGillette.com • BoycottBenetton.com • CASPIAN (Consumers Against Supermarket Privacy Invasion and Numbering)

  12. Blocker Tag Reference: http://www.rsa.com/rsalabs/staff/bios/ajuels/publications/blocker/blocker.pdf

  13. Blocker Tag Reference: http://www.rsa.com/rsalabs/staff/bios/ajuels/publications/blocker/blocker.pdf

  14. Tree Walking protocol

  15. Basic Working • Reader recursively asks the tags • “What is your next bit?” • The tag replies “0” and “1” both • Reader thinks that all the possible tags are present. • Reader stalls as number of possibilities are huge. • Possibilities are at least 264 in most basic systems. • This is “universal blocker” tag

  16. Reference: http://www.rsa.com/rsalabs/staff/bios/ajuels/publications/blocker/blocker.pdf

  17. Selective Blocking • Blocker Tag can block tags within certain zones. Such zones are “privacy zones” • Tags can be moved between zones. • For Example • The “blocker tag” block tags with leading “1” • Retail store items have tags with prefix 0 • At check out counter the leading bit is flipped from “0” to “1”

  18. Blocking with Privacy Zones Reference: http://www.rsa.com/rsalabs/staff/bios/ajuels/publications/blocker/blocker.pdf

  19. Polite Blocking • Singulation protocol can be revised to make it work efficiently with the blocker tags. • Aim of the blocker is to keep functionality active when desired by the owner. • If the reader tries to read the tag it will stall. • The tag informs the reader about its presence. • Before asking for next bit the protocol asks “Is the sub tree rooted at this node blocked”

  20. Leading bit is flipped to “1” and a blocker tag is provided to the customer Tags contain leading ‘0’ bit

  21. Strengths / Main Contribution • Low Cost Implementation • Ordinary consumer RFID-tag may not need to be modified at all. • Blocker tags can be cheap. ( Around 10 cents per tag) • Implementation is not resource intensive. Need to manage passwords for authorizing change to privacy zones

  22. Weakness • Reader can probably sense the existence of two tags transmitting at close proximity and can still traverse the privacy zone sub tree. • Consumers must take the step of protecting their own privacy (“opt-out” policy). The consumers might prefer an “opt-in” Policy

  23. Suggested Improvements • Research an “Opt in” approach like soft blocking.

  24. Questions ?

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