Android-supported Briefcase Locking Mechanism

By Pablo Bidwell and Tyler Green

Objectives To have a briefcase that opens with a wireless

command via Smartphone application

Portable power and ability to recharge when necessary

Software security implementation with one-time password scheme

Usage Send command from Android application

Raspberry Pi sends signal to solenoid

Solenoid retracts and briefcase can be opened

Software• Raspberry Pi runs Debian Linux• Socket server written in C waits for

connection from Android device

• Android connects to RPi with Java sockets over WiFi

• Authenticates with Lamport’s One-Time Password scheme

SoftwareOne-Time Password scheme

• Hash function H() (MD5 in our case), t=100

• Android device connects• RPi sends a challenge c. (1 <= c < t)• Android calculates Ht-c(p), sends to RPi• RPi, has p’ = H(p) stored,

• Computes H^(t – c – 1)(p’)• RPi compares its value to the one

received from the Android device.• If they match, the authentication is

successful and the briefcase is unlocked.

• Otherwise, the authentication fails.• In either case, c is incremented for the

next round.

Hardware and Design Solenoid door lock used to secure briefcase NPN transistor to turn solenoid on and off 12-volt battery needed to power solenoid

Hardware and Design Raspberry Pi is the “brain” of the project

Takes 4 Watts to power in normal operation Wi-Pi and SD card attached

Takes 5 volts and outputs 3.3 volts

Testing and Results Power Test

Calculated: 9 hours, 3 minutes Actual: 7 hours, 46 minutes

Physical Integrity Test Success

Budget

Briefcase Budget    Total: $332.95  

Part Vendor Price Total Price QuantityRaspberry Pi Allied Electronics $35.00 $140.00 4

Wi-Pi Amazon $17.40 $17.40 112V Battery All-Battery $17.99 $35.98 2

12V Recharger All-Battery $18.99 $18.99 1Solenoid Lock Amazon $15.68 $15.68 1

Briefcase Overstock $59.99 $59.99 1Metal Bar Ace Hardware $5.99 $5.99 1Transistors Radioshack $1.50 $9.00 6

LEDs Radioshack $0.99 $2.97 3Protoboard Radioshack $4.99 $4.99 1

Solder Radioshack $2.99 $2.99 1Diodes Radioshack $2.99 $5.98 2

Voltage Regulator HobbyKing $12.99 $12.99 1

Conclusion Future Plans (If we were to do it again)

Use Bluetooth instead of Wi-Fi Create custom briefcase to hide electronics and

use printed circuit board instead of protoboard Explore different controllers (Arduino, FPGA, etc.)

Thank You