Ch. 17: Security of RFID

1. Ch. 17:Security of RFID • slide 1

2. Roles of RFID applications Secure channel Tags Reader Server(Database) Slides modified from presentation by Prof. HM Sun • slide 2

3. Security Problems of RFID • Eavesdropping • Hot-listing • Attacker has special interests in certain items • Replay attack • Cloning • Tracing • Data forging • Denial of Service Fundamental problem: Lack of mutual authentication • slide 3

4. Physical Solutions for RFID • slide 4

5. Physical Solutions • Kill tag after purchase • Faraday cage • Active jamming • Disables all RFID, including legitimate applications • Guardian • Blocker Tag • slide 5

6. Killing approach • Special command permanently de-activates tag after the product is purchased • Disables many futuristic applications Reference www.rsa.com/rsalabs/staff/bios/ajuels/ • slide 6

7. Faraday Cage • Container made of foil or metal mesh, impenetrable by radio signals of certain frequencies • Shoplifters are already known to use foil-lined bags • Maybe works for a wallet, but huge hassle in general Reference www.rsa.com/rsalabs/staff/bios/ajuels/ • slide 7

8. Blocker Tag (The RXA Pharmacy) Reference http:// www.rfidjournal.com • slide 8

9. Active Jamming (Guardian) • A mobile battery-powered device that offers personal RFID security and privacy management. Reference http:// www.rfidguardian.org • slide 9

10. How Does the Reader Read a Tag? • When the reader sends a signal, more than one RFID tag may respond: this is a collision • Reader cannot accurately read information from more than one tag at a time • Reader must engage in a special singulation protocol to talk to each tag separately • Tree-walking is a common singulation method • Used by 915 Mhz tags, expected to be the most common type in the U.S. Reference www.cs.utexas.edu/~shmat/ • slide 10

11. Reference www.cs.utexas.edu/~shmat/ Blocker Tag : Tree Walking prefix=0 prefix=1 Reader broadcasts current prefix Each tag with this prefix responds with its next bit prefix=00 prefix=01 prefix=10 prefix=11 If responses don’t collide, reader adds 1 bit to current prefix, otherwise tries both possibilities 000 001 010 011 100 101 110 111 Every tag has a k-bit identifier This takes O(k  number of tags) • slide 11

12. Collision! No collision No collision No collision Collision! 3. ID=001 3a. ID=110 Talk to tag 001 Talk to tag 110 3b. ID=111 Talk to tag 111 Next=1 Next=1 Next=1 Next=1 Next=0 Next=1 Next=1 Next=0 Next=0 Reference www.cs.utexas.edu/~shmat/ Blocker Tag : Example 1. Prefix=“empty” prefix=0 prefix=1 1a. Prefix=0 1b. Prefix=1 2. Prefix=00 2. Prefix=11 prefix=00 prefix=01 prefix=10 prefix=11 000 001 010 011 100 101 110 111 • slide 12

13. Reference www.cs.utexas.edu/~shmat/ Blocker Tag [Rivest, Juels, Szydlo] • A form of jamming: broadcast both “0” and “1” in response to any request from an RFID reader • Guarantees collision no matter what tags are present • To prevent illegitimate blocking, make blocker tag selective (block only certain ID ranges) • E.g., blocker tag blocks all IDs with first bit=1 • Items on supermarket shelves have first bit=0 • Can’t block tags on unpurchased items (anti-shoplifting) • After purchase, flip first bit on the tag from 0 to 1 • slide 13

14. 行動票券之安全議題 * slides modified from presentation by 何煒華 高鐵車票 14

15. 安全議題 竄改 偽造 盜用 複製、重複使用 移轉(vs. 複製) 15

16. Summary • Security Concerns of RFID • Security Concerns of 行動票券