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Distributed, Consistent
and Secure USB Storage
Midyear Design Review
Eddie Lai
Matt Dube
Sean Busch
Zhou Zheng
Team Wolf
Outline
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PDR Summary
Design Implementation
Proposed MDR Deliverables
Demonstration
CDR Deliverables
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Project Summary
 A device that distributes backups
across several USB drives
 Maintains consistency as long as
the backups are conflict free
 Distributes backups to devices
interfaced across a network
 Requires minimal user input
Team Wolf
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Secure Application
 (k, n) threshold scheme
 Requires a subset, k, of a set, n, to recover data
 With fewer than k pieces, no information about the data can
be recovered
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Project Design Implementation
 Parts to be implemented
• Custom Software
• Network Interface
• PC interface
 Rest provided by Atom
development board
Team Wolf
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Custom Software
 Sending hub
• Save listing of checksum, timestamps, and folder paths at one time
• Save listing at a later time and “diff” the two records
• Process changes and send to other hubs
 Receiving hub
• Record the “USB Network” from the received update
• Iterate through each USB to check if they belong to the USB Network
• Distribute updates
Team Wolf
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Network Interface
 TCP/IP socket connection over a LAN
• Unsecure
 Client/server model
• Server – wait for connection from client with update messages
• Client – connect to server, send update messages, then disconnect
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PC Interface
 Hub should appear as a USB mass storage device
• Hub must act as a USB device (slave) to PC (master)
 Developing this interface has been a significant challenge
• USB protocol deliberately very uneven
− Most of the software and hardware located on host side
− Not meant for PC to PC (host to host) data transfer
• Atom development board only contains USB host ports
− Would require additional hardware and drivers
Team Wolf
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PC Interface Solutions
 Bridge cable
• Cable with USB A at each end
• Embedded system in-between
• Enables PC to PC file transfer
 I2C USB slave adapter
• Philips ISP1301 USB OTG
• Would allow the Atom to interface with USB physical layer
• Requires additional hardware and overhead
 Different embedded system
• Beagle Board
Team Wolf
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Beagle Board
 Low power, low cost system on chip
 Slight reduction in performance vs Atom
• ARM ® Cortex TM -A8 MHz at 1 GHz
• 512MB of low-power DDR RAM
 Tiny 3.25" × 3.25" footprint
 4 USB hosts and 1 USB OTG 2.0 port
• OTG port allows board to act as USB device
• Would handle same number of USB drives as atom board
• $149.99 price point
Team Wolf
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Proposed MDR Deliverables
 2 hubs based on Advantech Intel Atom board
 Initialize and authenticate hubs to each other
− Authenticate USBs to hub-network
 Detect and distribute updates
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Demonstration
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Performance Data
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Performance Data
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Proposed CDR Deliverables
 PC interface
• Hub will appear to user’s PC as single USB Mass Storage Device
 Secure socket connections
 User interface for initializing and configuring the system
• User should be able to use web browser to access interface
 Physical user interaction with hub
• Buttons to initiate sync and ejections
• LEDs to indicate sync in progress and when its ok to eject
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Questions
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