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The Blocker Tag: Selective Blocking of RFID Tags for Consumer Privacy. A. Juels, R. L. Rivest, and M. Szydlo 8th ACM Conference on Computer and Communications Security, pp. 103-111. ACM Press. 2003. Presented by: Sean Mondesire. Contributions. Blocker Tags: Protects consumer privacy
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The Blocker Tag: Selective Blocking of RFID Tags for Consumer Privacy A. Juels, R. L. Rivest, and M. Szydlo 8th ACM Conference on Computer and Communications Security, pp. 103-111. ACM Press. 2003. Presented by: Sean Mondesire
Contributions • Blocker Tags: • Protects consumer privacy • Relatively inexpensive • Proves the RFID Bill of Rights and practical tags can coexist The Blocker Tag
Agenda • RFID Tags • Security Issues • Previous Work • Blocker Tags • Privacy Protection • Malicious Blocker Tags • Critique The Blocker Tag
RFID Tags • Simple Radio-Frequency Identification Tags • Passive: Battery-less • Contain an assigned serial number • Can be modified • Replacement for the barcode • Cost about 5 cents • No more laser scanning • Consumers can use the benefits The Blocker Tag
Security Issues • Eavesdroppers • Gather what items are in your possession • Privacy Violation Examples • Dress size • Medication • Amount of money in wallets • Petty Thieves • Modify serial numbers in store • Deactivate tags before purchase The Blocker Tag
Previous Work • “Kill Tag” • Faraday Cage • Active Jamming • “Smart” RFID Tags • Hash-Locks • Re-encryption The Blocker Tag
Tree-Walking Singulation • Singulation • Reader processes one tag at a time • Tree-Walking Singulation Algorithm • Recursively signal tags with next prefix • Tag with prefix respond with next prefix 0 1 00 01 10 11 The Blocker Tag
Blocker Tags • Goal: • Protect the privacy of consumers affordably • Motivation: • Guaranteed privacy will push the use of RFID tags • How They Work • Universal Blocker: For every signal send 0 and 1 • Selective Blocker: Block a subset of tags The Blocker Tag
Privacy Protection Tool • Selective Blocker: • Forces readers to signal nonexistent and existent tags • Readers cannot guarantee tags are in the vicinity • Hides tags with false signals • Supermarket Example: • Shelved items start with 0 • Purchased items tags set to 1 • Sticker of a blocker tag placed on item’s tag (blocks 1’s) The Blocker Tag
Malicious Blocker Tags • Blocker tags that do not respect the privacy zones • Blocker signaling 0’s in previous example • Universal blockers are malicious • DOS attacks on readers • Universal blockers: Readers signal all possible serial numbers • Selective blockers: Simulate actual tags that should not be scanned at that time The Blocker Tag
Strengths • Inexpensive • RFID to reply to signals • Less than 10 cents to manufacture • Satisfies the RFID Bill of Rights • Simple to implement • Create tag that returns 0 or 1 when ever signaled The Blocker Tag
Weaknesses • Can force DOS on reader • Encourages nonsense broadcasts • Requires additional RFID tags • Forces consumers to have blocker tags to guarantee privacy • Many unanswered questions: • What if malicious blocker tags were left throughout a store? • Thieves can swap tags easier than barcodes The Blocker Tag
Areas of Improvement • Improve inefficiencies placed on the Reader • Universal Blocker impractical • Limit blocking capabilities • Incorporate blockers within each tag • Cost for addition registers should be comparable to having separate blockers The Blocker Tag
Related Work • RSA Laboratories • Inventors of RSA public-key cryptosystem • Focus on RFID privacy and security • Soft Blocking • Encryption in RFID • RFID chips can carry a virus • Amsterdam’s Free University • RFIDs can return data to infect a reader’s DB • Can spread to other tags The Blocker Tag
Contributions • Protects consumer privacy • Readers can’t pinpoint existing tags • Relatively inexpensive • About 5 cents for one antennae • At most 10 cents per blocker • Proves the RFID Bill of Rights and practical tags can coexist • No sacrifices on consumer rights The Blocker Tag
References • Juels, A., Rivest, R. L., and M. Szydlo, “The Blocker Tag: Selective Blocking of RFID Tags for Consumer Privacy,” 8th ACM Conference on Computer and Communications Security, pp. 103-111. ACM Press. 2003. • Reuters, “Scientists: RFID Chips Can Carry a Virus”, http://www.cnn.com/2006/TECH/ptech/03/15/rfid.virus.reut/index.html, CNN.com, March 15, 2006 • RSA Laboratories, http://www.rsasecurity.com/, March 28, 2006. The Blocker Tag