1. Using A Two Dimensional Colorized Barcode Solution for Authentication in Pervasive Computing
William Claycomb and Dongwan Shin
New Mexico Institute of Mining and Technolgoy
June 28, 2006

2. Acknowledgement New Mexico Tech Graduate Student Association ICPS 2006
2 December 2018

3. Agenda Introduction and Background Motivation UbiColor
Testing and Results
Analysis
Practical Applications and Advantages
Future Work
Questions
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4. Introduction
The use of mobile devices in pervasive computing environments is growing
The types of interactions available are also increasing
The security of these interactions needs to be addressed
Particularly in one-to-one situations
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5. One-to-one Communications
Alice
Bob ↔
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6. Background Authentication and Key Exchange
Devices need to authenticate for key exchange to occur
“Resurrecting Duckling”
Location limited channels
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7. Background Using Digital Cameras Visual tags
Capture an image of a tag and decode information contained within
Establishing a communication channel
Demonstrative identification
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8. Background Using Visual Tags for Authentication and Key Exchange
UbiCode
Developed by Shin and Im, 2005
Two Dimensional barcode for ad-hoc device authentication
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9. UbiCode
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10. Motivation to Improve Ubicode limitations Mobile device improvements
Small “pixel” size
IPv4 address space
128 bit hash algorithm
Mobile device improvements
Higher resolution cameras
Bright, colorful displays
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11. Improvement: UbiColor
Expand barcode capacity by adding color
Increase “pixel” size by reducing the number of “pixels” needed to convey information
Increase the amount of information contained in the barcode
Utilizes existing capabilities of mobile devices
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12. UbiColor Color Chart
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13. UbiColor
A UbiColor Visual Tag
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14. UbiColor Tag Detail
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15. Ubicolor Tag Detail
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16. Establishing a Secure Connection
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17. Agenda Introduction and Background Motivation to Improve UbiColor
Testing and Results
Analysis
Practical Applications and Advantages
Future Work
Questions
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18. Testing Control Images Brightness Rotation Tag Size within image
Distortion
Blurriness and Noise
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19. Testing – Digital Photos
Variables
Room lighting
Background surface color
Picture resolution
Device brightness
Size of tag within image
Display device
Camera
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20. Testing – Platform and Setup
Three testing platforms
Dell Latitude D600
Dell Axim X50v PDA
HP iPAQ rx3715 PDA
Setup
Three images taken of each configuration
All images tested on each device
576 images – 1584 total tests
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21. Results
Display a visual tag
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22. Processing Control Images
Brightness
Positive brightness: 10%, 20%, 30%, 40%
Negative brightness: -10%, -20%, -30%
Rotation
Positive rotation angle: 1, 2, 5, 10, 20, 30
Negative rotation angle: 1, 2, 5, 10
Size of Visual Tag Within the Image
Visual tag width to image width: 30%, 40%, 50%, 60%, 70%, 80%, 90%
Distortion
Horizontal Distortion
Positive (right side) distortion: 5%, 10%, 15%, 20%, 30%, 40%, 45%
Negative (left side) distortion: 5%, 10%, 15%, 20%, 30%, 40%, 45%
Vertical Distortion
Positive (bottom) distortion: 5%, 10%, 15%, 20%, 30%, 40%, 45%
Negative (top) distortion: 5%, 10%, 15%, 20%, 30%, 40%, 45%
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23. Processing Digital Photos - Time
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24. Performance – Data Extraction
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25. Performance – Establishing Secure Communication
Algorithm time: < 1 second
Network time: 1 – 6 seconds average ↔
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26. Agenda Introduction and Background Motivation to Improve UbiColor
Testing and Results
Analysis
Practical Applications and Advantages
Future Work
Questions
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27. Analysis Cameras make a big difference
Current state of digital camera technology in smart devices
5.0 megapixels coming soon!
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28. Analysis – Control Images
Rotation Issues
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29. Analysis – Digital Photos
Resolution
Higher resolution picks up more detail
This is not a good thing…
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30. Analysis – Digital Photos
Brightness
Half-brightness better overall, but not that much difference
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31. Analysis – Digital Photos
Background room lighting
Device background color
Neither make that big of a difference
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32. Analysis – Digital Photos
Display Device
Major flaw discovered in implementation
Color detection algorithm uses “first match,” rather than “best match.”
Correct is on the left
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33. Analysis – Digital Photos
Tag size within image
Better chance of error with large tag
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34. Agenda Introduction and Background Motivation to Improve UbiColor
Testing and Results
Analysis
Practical Applications and Advantages
Future Work
Questions
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35. Practical Application Scenario
ATM
Capture visual tag image from ATM
Establish secure connection
Authenticate user
Several storage methods for this
Interact with ATM via mobile device
ATM responds when appropriate
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36. Practical Application Scenario
ATM (cont)
Advantages
Less physical use of service device
More options for physically locating the device
Personalization is possible
Additional physical security
No need for ATM card
Protection from “skimming”
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37. Practical Application Scenario
Vending Machine
Capture image of visual tag from vending machine
Establish secure connection
Interact with vending machine
Receive product information
Make purchases using digital cash, credit card, store credit, etc.
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38. Practical Application Scenario
Vending Machine
Advantages
Product selection can be externally controlled
Payment information can be stored on the device, but that is not required
Electronic receipts
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39. Advantages of this Approach
This approach provides a secure communication channel
Particularly useful for sensitive transactions
Easily adaptable to various networking environments
Adaptable to various computing platforms
Does not require presence of CA
External connection not required, unless further user authentication is necessary
This approach does not require the use of device discovery protocols
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40. Advantages of this Approach
Security
Man-in-the-middle attack prevented
Misidentification of tag information is not a threat
The incorrectly identified host will not have the correct public key
Keys change with every instance of communication
The of pre-printed, superimposed visual tags for and attack is possible, but not likely
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41. Agenda Introduction and Background Motivation to Improve UbiColor
Testing and Results
Analysis
Practical Applications and Advantages
Future Work
Questions
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42. Future Work Design Changes Corners Error correction
Visual Tag Identification
Alignment
Error correction
Exists in other 2D barcodes already
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43. Additional Colors? Additional Colors
Adding 8 colors would increase the “bitrate” by 33%
Can the application distinguish these colors?
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44. Future Work Application Changes Improve tag identification
Improve color recognition
Two-way communication
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45. Future Work
Group Communication
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46. Questions
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