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©2006 Sanjay Sarma
RFID and Security
Sanjay SarmaMIT and CTO of OATSystems
2 ©2005 OATSystems©2006 Sanjay Sarma
Everything is different with RFID
Power is limitedCost is an issueBandwidth is limitedMemory is a premiumData is fast but… fallibleTag connectivity is sporadicThe range of applications is largeThe range of related technologies is huge
3 ©2005 OATSystems©2006 Sanjay Sarma
History (See “Shrouds of Time The history of RFID,” Landt 2001)
1948: Backscatter– Stockman, H. "Communication by Means of Reflected Power",
Proceedings of the IRE, pp1196-1204, October 1948. 1974: Automotive license plates– Sterzer, F., "An electronic license plate for motor vehicles", RCA
Review, 1974, 35, (2) pp 167-175 1998: DISC, Auto-ID Center founded at MIT2001: First standards presented2002: Gillette orders 500,000,000 tags from Alien 2003: Wal-Mart, DoD Mandates– EPCglobal launched, Center retired– HP sits on the board2004: More mandates2005: First bulk tagging– Emergence of Gen 2– Multi-site deployments– Beginnings of value2006: Next Generation research
4 ©2005 OATSystems©2006 Sanjay Sarma
History of the EPC
1998-1999: DISC, Auto-ID Center founded at MIT2001: First standards presented2002: Gillette orders 500,000,000 tags from Alien 2003: Wal-Mart, DoD Mandates– EPCglobal launched, Center retired
2004: More mandates2005: First bulk tagging– Emergence of Gen 2– Multi-site deployments– Beginnings of value
5 ©2005 OATSystems©2006 Sanjay Sarma
Low cost RFID
time
5
10
15
20
die
size
/cos
t, ce
nts
handling costSilicon: 4c/mm2
6 ©2005 OATSystems©2006 Sanjay Sarma
The stack
Readers
tags tags tags
CompanySoftware
Gen 1air-interface
Savant
ONS
Readers
tags tags tags
ERP+RFIDSoftware
Company #1 Company #2
Readerinterface
Gen 2air-interface
Reader Protocol
EPC-IS
ONS + Blob
7 ©2005 OATSystems©2006 Sanjay Sarma
RFID Systems
ID– Electronic product code: header:manufacturer:product:serial– Read-write extra memory/sensory dataAnti-collision– One reader can read many tagsReader coordination– Make sure readers don’t interfere with each otherMiddleware– Collect all the data and make sense of it
8 ©2005 OATSystems©2006 Sanjay Sarma
How EPC Gen2 works
RF level– Multiple speeds– Dense-mode– Many dials for EU,
Asia, US operationLogic level– Generalized
selection– Advanced sessions– Advanced payload
etc. access
Generalized Selection
Anti-collision (Query)
Access of payload
Entire population
Thinned population
Single tag identified
Payload from tag
9 ©2005 OATSystems©2006 Sanjay Sarma
My focus today
Classes of tags
Passive– No battery;
chip runs on scavenged power
– Communication by backscatter only
– 10m rangeSemi-passive– Battery to run the chip– Communication by
backscatter only– 50m range
Active– Battery runs the chip– Communication by
transmission– 100+m range
• Forward bandwidth is low• Low compute cycles for power• Power limited range• Weak backscatter
• Forward bandwidth is higher• Faster cycles for power• Strong backscatter• Wake-up circuit
• Endless possibilities
Do not confuse with near-field tags and smart-cards
©2006 Sanjay Sarma
How RFID is used in the supply chain
11 ©2005 OATSystems©2006 Sanjay Sarma
Inventory
TAG EPC
TIME
LOCATION
12 ©2005 OATSystems©2006 Sanjay Sarma
The Trace
TAG EPC
TIME
LOCATIONTheft!!
Counterfeit!Diversion!
13 ©2005 OATSystems©2006 Sanjay Sarma
The Flow
TAG EPC
TIME
LOCATION
RECALL!!!
14 ©2005 OATSystems©2006 Sanjay Sarma
Supply Chain Problems
TAG EPC
TIME
LOCATION
RFID enables • Real-time detection of
errors• Real-time correction• Run-to-run improvement
i.e., tactical, operational, strategic enhancement.
Errors making plans less effective
©2006 Sanjay Sarma
On security of passive and semi passive tags
16 ©2005 OATSystems©2006 Sanjay Sarma
Privacy: The very act of detection poses a challenge
Readers and tags cannot hide their very presence– Sniffing
The structured ID could be a problem– header:manufacturer:product:serial– Do I want people to know I am taking a Pfizer product?
Repeated unique numbers are a problem– Track based on repeated ID
Constellations of non-unique numbers are a problem– I may be the only person in Graz
with a Titan watch and Docker pants
17 ©2005 OATSystems©2006 Sanjay Sarma
Some problems can be solved
Readers and tags cannot hide their very presence– Sniffing
The structured ID could be a problem– header:manufacturer:product:ser
ial– Do I want people to know I am taking
a Pfizer product?
Repeated unique numbers are a problem– Track based on repeated ID
Constellations of non-unique numbers are a problem– I may be the only person in
Graz with a Titan watch and Docker pants
Spread spectrum, etc. expensive.
Non-structured numbers, special ONS for sorting them out
Temporary ID by encrypting EPC|nonceShared key, so key-management problem
18 ©2005 OATSystems©2006 Sanjay Sarma
The fact of the matter is
Can’t do anything beyond hashes in passive RFID tagsPhysics is our best friend– Can’t activate from afar– Can’t hear backscatter from afar– Consider backscatter channel a private channel
There is a physical zone of trust for privacy– Tag response audible a few meters– If you have worries, you can create further physical
barriers• Shielding• Killing the tag
– Famous EPC kill code
• Reduced range mode of tags• Personalization of tags
19 ©2005 OATSystems©2006 Sanjay Sarma
Some of the other issues
Privacy violation is a consequence of unauthorized reading– Other privacy protections– Detection of unauthorized readers
EavesdroppingUsing tags to prevent counterfeits– Skimming the tag and replaying– Tampering with the physical artifact
Prevent tag hijack
20 ©2005 OATSystems©2006 Sanjay Sarma
Other issues in unauthorized reading
Perhaps require readers to announce themselves– What if reader announced its name, ID, and function– Tag detects this and chooses not to respond– Too expensive – Too voluntary
The Sentinel Concept– Blocker Tag from Juels et. al. Logical jamming when
readin some tags– The Watchdog Tag from Floerkemeier (upcoming
PhD thesis)Sarma’s vindictive Sentinel– All readers need to register with guardian– If a reader is not registered, Sentinel will jam the
channel– No politeness
21 ©2005 OATSystems©2006 Sanjay Sarma
Eavesdropping
A reader in Wal-Mart is readings its tags– Readers put out ~watts
A competitor is sitting outside listening to the reader– Can it infer the contents?
Tag response unlikely to be decipherablePut secret information in tag response channelThe forward response is now XOR’ed with previous reverse channel secret– Blind-tree walking by [Weis 03]
22 ©2005 OATSystems©2006 Sanjay Sarma
Eavesdropping is easier when Gen 2 Masking is used
You are listening from a distanceYou hear the selection commandYou see the number of responses that were receivedYou can detect the numbers of tags in a population
Solution is: – Use masking judiciously– Use chaff when necessary– Sentinel Tag generates
chaff, notifies middleware– The Sentinel Tag again!
Generalized Selection
Anti-collision (Query)
Access of payload
Entire population
Thinned population
Single tag identified
Payload from tag
23 ©2005 OATSystems©2006 Sanjay Sarma
Counterfeit detection
Some secret on the tag which you can verifyCan do it by hash, symmetric or asymmetric cryptoEasier to do in near-field or semi-passive/active tagsHarder to do in RFID– Limited gates– Limited compute cycles– Ephemeral contact
Killer app for RFID– Counterfeit market worldwide is very large ($500B?
See Staake’s work)– The very presence of an RFID tag is also a defense– The history of a serialized number is further defense
24 ©2005 OATSystems©2006 Sanjay Sarma
Low-Cost Hash Design [Weis 2003]
Traditional: Many Gates, Few Cycles – Expensive– High-power
Low-Cost: Few Gates, Many Cycles– Slow
Cellular Automata– Cellhash, 1993. No major breaks (yet).– Very cheap, fast and scalable.
Non-Linear Feedback Shift Registers:– Relatively cheap and flexible.– Lots of classified work.
25 ©2005 OATSystems©2006 Sanjay Sarma
The Digital Millennium Act
Can be used to stymie commodity replacements!Tags on cartridgesReaders in printersSome important content in tag: say colorsNon-copy-able
26 ©2005 OATSystems©2006 Sanjay Sarma
The Pink Panther replay scenario
Imagine diamonds in a display (each diamond has passive tag)Tags are being read continuously by readerPink Panther has a tag mimicking machine– Listens for the tags being read– Starts playing them back– While pink Panther steals the diamonds
One solution is a Sentinel Tag generating chaffMimicking machine cannot tell chaff from real contentWill replay chaffThe Sentinel Tag again
27 ©2005 OATSystems©2006 Sanjay Sarma
Writing to tags
Enter Code and LockKillWrite
Issues:Administering kill codesPreventing mass killing of tagsAdministering the other codesPersonalizing tags
28 ©2005 OATSystems©2006 Sanjay Sarma
Preventing mass kill
If the codes are not all set to 1111, then you can’t kill the tags easilyKilling is not an RF function in EPC tags; it is an addressed, logical request– You can only kill at the rate of anti-collision– You can only kill from the passive distance– From that range, you have other options open to you
Sarma’s Sentinel Tag: when you see an unauthorized kill going on, jam the airwaves!
The real challenge is kill code management: how does it pass from owner to owner?
29 ©2005 OATSystems©2006 Sanjay Sarma
A keyless approach to administration [Weis 03]
Reader Tag
metaID := hash(key)metaID
Store: (key,metaID)
metaID
Who are you?Store: metaID
Locking a tagQuerying a locked tagUnlocking a tag
keymetaID == hash(key)?
“Hi, my name is..”
30 ©2005 OATSystems©2006 Sanjay Sarma
Personalizing tags: an opportunity
Say you go to a store and buy a productThe product has a tagYou now want to personalize that tagYou have a little PDA which talks to the store reader and personalizes your tag
Your PDA is a personalizing device which now talks to your back-end system at home
– Tanenbaum et. al 05– Foley 05
31 ©2005 OATSystems©2006 Sanjay Sarma
The repeating themes
The backscatter distance is a zone of trust– No perfect, inexpensive solution beyond within that
zone of trust for passive tagsPassive tags cry for a Sentinel Tag– Sentinel can aggregate security/defense/privacy
functions which individual tags cannot afford– Turns out that there are several other
©2006 Sanjay Sarma
The System
33 ©2005 OATSystems©2006 Sanjay Sarma
The system
Readers
tags tags tags
CompanySoftware
Gen 1air-interface
Savant
ONS
Readers
tags tags tags
ERP+RFIDSoftware
Company #1 Company #2
Readerinterface
Gen 2air-interface
Reader Protocol
EPC-IS
ONS + BlobTransfer of codes,Data, etc.
©2006 Sanjay Sarma
Recent attacks
35 ©2005 OATSystems©2006 Sanjay Sarma
Viruses and Worms
Tanenbaum’s groupResearchers demonstrated a RFID virus:Based on an “SQL injection” attackWebsite: http://www.rfidvirus.org
Shamir’s groupSide channel attackPower analysis
©2006 Sanjay Sarma
Conclusions
37 ©2005 OATSystems©2006 Sanjay Sarma
The opportunities
Technology
TagsSemiconductorsPackagingProtocolsAntennaeReadersMiddleware/ReaderMiddlewareDatabasesEnterprise architectureDistributed systemsIdentity managementBusiness process
Applications
Supply chain– Retail– Healthcare– B2B– Critical goodsLogistics– Travel/airports– Defense– Heavy industries– Asset managementOperations– Factory– DC/warehouse– Institutions– MaintenancePersonal systems….
Analysis
RF SystemsCommunicationsSecuritySystem dynamics– Supply chain
• Planning • Execution• Policy
– Demand planning
Social/ethicalBusiness planningMacroeconomicsPolicy/frequency
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