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KAIST
Message-In-a-Bottle: User-Friendly and Secure Key Deployment for Sensor
Nodes
Cynthia Kuo, Mark Luk, Rohit Negi, Adrian Perrig(CMU), Sensys07
2007. 11.22
Kim Taesung
A Secure Group Key Management Scheme for Wireless Cellular Network
Contents
Introduction
Problem Definition, Assumptions and Attacker Model
Protocol for Key Deployment
Security Analysis
Implementation
Radio Measurement
User Study
MIB for Multiple Nodes
Discussion
Comparison Related Work
Conclusion
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A Secure Group Key Management Scheme for Wireless Cellular Network
Introduction
Deploying cryptographic key in a secure manner to sensor node is a prerequisite for secure sensor network.
Secure key establishment rely on a pre-existing shared secret.
TinySec, SPINS, ZigBee security.
ZigBee security provides two suggestions
Cryptographic keys could be sent in the clear.
Factory could imprint keys on sensor nodes.
Message-In-a-Bottle(MIB)
Secure mechanism for initial key setup
Four properties
No physical interfaces
Secure key deployment, wirelessly
Key deployment by non-expert
Batch deployment for multiple nodes
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Problem Definition
How can a shared secret be set up between a trusted base station and each new uninitialized node?
Solution provides properties.
Key secrecy
Key authenticity
Forward secrecy
Demonstrative identification
Robust to user error
Cost effective
No public key cryptography
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Protocol for Key Deployment
MIB Participants
Base Station
The base station is not directly involved with key deployment.
New Node
Three states: uninitialized, initialized, and rejected
Keying Device
The keying device sends keying information to the new node when the Faraday cage is closed.
Keying Beacon
Three purposes: 1) detect when the Faraday cage is closed; 2) jam the communication channel; 3)inform the user of outcome of the deployment.
User
The user of MIB is the person who performs key deployment
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Overview of MIB Protocol
Each mote has three color LEDs: Red, Green, and Blue.
You will be working with three types of motes: Controller, Numbered Mote, Secret Keeper.
Step 1.Verify that all three LEDs (red, green, and blue) on the Controller and the Secret
Keeper are
blinking simultaneously.
Gently place the Numbered mote in the container.
Step 2.Screw the cap on the container snugly.
When no radio signals can escape the container, the Controller’s blue LED will be lit.
Step 3.Wait until the Controller begins to blink its blue LED. This should take about 5
seconds.
Step 4.Open the container and remove the Numbered mote. Record the result on the
Results page.
• If the Controller’s green LED is lit, encryption keys were successfully exchanged.
• If the Controller’s red LED is lit, the key exchange process was not successful.
• It does not matter what color (if any) the Numbered mote is lit.
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Overview of MIB Protocol
Why is a Faraday cage insufficient?
In practice, Faraday cage is imperfect; it can not block radio signals completely.
Usability issues.
Protecting shielded messages
Faraday cage.
Messages are transmitted at minimum power.
Keying beacon jams the wireless frequency.
No spread spectrum.
The secret key is a function of all the shielded messages.
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Detailed Description
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Notation
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Setup Keying Device and Keying Beacon
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Heartbeat Messages
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Deploy Cryptographic Keys
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Key Activation and Verification
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After Key Deployment
Initialized node M
Node identifies itself with ID M, counter c and keying device’s ID D.
Base station can generate KM
Base station possesses the master secret.
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Security Analysis
Obtain Key KM through eavesdropping
Inject a malicious key onto the new node
Compromise the network by compromising the keying device
Initiate key deployment before the Faraday cage
Prevent the keying beacon from jamming during key deployment
Wait for the user to make an error
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Implementation
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User study
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MIB for Multiple Nodes
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Comparison with Related Work
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A Secure Group Key Management Scheme for Wireless Cellular Network
Time for
Any questions?
Thank you for listening !
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