USB Auth

Here's the video of the project: http://www.youtube.com/watch?v=Fa5RuWM1fEM

USB Authentication

Pros

Each USB device has a unique serial ID. USB keys are cheap, readily available, and many can fit on a standard metal keyring.

Implementation

Authentication Flow

1. User inserts key into USB hub hooked to a PC
2. Computer reads serial ID of key
3. Computer compares serial ID to list of valid serial ID in a table \ DB \ Flat File
4. If good, computer writes data ("Unlock!") to USB line of Microcontroller
5. Microcontroller instructs servo to go to unlocked position for 5-10 seconds.

Code

USB Reader Code

#!/bin/sh

# variables!
mymu=A6005ycb
mydev=/dev/ttyUSB0
mydb=usb-keys.txt

# first, define some common functions
function lsserial {
	lsusb -v | awk '/iSerial/ {if ($2 == "3" || $2 == "2") {print $3}}'
}

# figure out whats attached
# check for our microcontroller
if [ $(lsserial | grep -c $mymu) = 0 ] ; then
	echo -n "I don't see the microcontroller "
	if [ -e $mydev ]; then
		echo "but we have a $mydev ?"
	else
		echo
	fi
	exit 1
else
	if [ ! -e $mydev ]; then
		echo "I see the microcontroller, but no $mydev"	
		exit 1
	fi
fi

if [ -e $mydb ] ; then
	echo "Found serials for the following people:"
	awk -F, '{print $1}' $mydb
else
	echo "Didn't find keyfile $mydb"
	exit 1
fi

# all good, lets go
preserial=$(lsserial | grep -v $mymu)
if [ -n "$preserial" ]; then
	echo "I've detected the following serial devices already:"
	echo $preserial
fi

echo "Ready and waiting"

# main loop that watches /var/log/messages
(
	tail -n 0 -f /var/log/messages | awk '/new.*USB device/ {print "Attached"; fflush()} /USB disconnect/ {print "Dettached"; fflush()}'
) | (
# main loop that reads that cleaned /var/log/messages
	while read cmd; do
		if [ $cmd == "Attached" ] ; then
			for ser in $(lsserial | grep -v $mymu); do
				echo "Checking for $ser in flat file"
				if [ $(grep -c $ser $mydb) = 1 ]; then
					name=$(awk -F, "/$ser/ {print \$1}" $mydb)
					echo "Unlocking for $name!"
					echo -n U > $mydev
					error=$?
					if [ $error != 0 ]; then
						echo "There was an error ($error) writing to $mydev"
					fi
				else
					echo "Didn't find it in flat file"
				fi
			done
		else
			echo "Got $cmd but nothing implemented for it"
		fi
	done
)

Freeduino Code

1. include <Servo.h>

1. define interrupt1PinA 3

volatile unsigned int interrupt1Value = 0;

char incomingChar = 0; Servo myServo; int pos; int DoorSensePin = 2; //this is the PIN that the reed switch is connected to int lockedPosition = 115; //This is the value that the servo wants to be at the correct physical position int unlockedPosition = 28; //This is the value that the servo wants to be at the correct physical position

boolean HasForceUnlockHappened = 0; //this is used by the interrupt routine as a workaround to using timers

void setup() {

 Serial.begin(9600);
 Serial.flush();
 
 myServo.attach(9);  // attaches the servo on pin 9 to the servo object 
 Lock();  //default to locked position at powerup
 //myServo.write(28); //default to locked at powerup
 
 pinMode(DoorSensePin, INPUT);  //designate pin2 as a sensing (input) pin  
 pinMode(interrupt1PinA, INPUT);  
 
 attachInterrupt(1, ForceUnlock, HIGH);  //when interrupt happens, run ForceUnlock function

}

void ForceUnlock() //it is important that no timer related functions happen during an interrupt routine {

   Serial.println("Force Unlock Button Pressed! Interrupt Called!");
   myServo.write(unlockedPosition);  //cannot call regular Unlock function as it has a delay() call  
   HasForceUnlockHappened = 1;

}

void loop() {

 //Serial.println("In Main Loop");  //TROUBLESHOOTING LINE
 if (HasForceUnlockHappened == 1) //if an interrupt driven ForceUnlock has happened, then need to WaitToLock
 {
   HasForceUnlockHappened = 0;  //reset till next interrupt
   WaitToLock();
 }  
 if (Serial.available() > 0)
 {
    incomingChar = Serial.read(); 
    
    Serial.print("I recieved: ");
    Serial.println(incomingChar, DEC);
    //Serial.print("The DoorSense Value is: ");
    //Serial.println(IsDoorOpen(), DEC);
   
   // Code for Unlocking Door.  Unlock does not care if door is closed or not.
   if (incomingChar == 85) //"U" is 85 in DEC.  U is for Unlock
   {
          Serial.println("Unlocking!");          
          Unlock();
   }

   //Code for Locking Door.  Lock cares if door is open or closed.
   if (incomingChar == 76)  //"L" is 76 in DEC.  L is for Lock
   {
        if (IsDoorOpen() == 0)  
        {
          Serial.println("Locking!");          
          Lock();
        }    
        if (IsDoorOpen() == 1) { Serial.println("Door is Open!!"); }         
   }
   
 }// if serial end

}//loop end

//IsDoorOpen should return a 1 if Door is Open, and a 0 if Door is Closed. boolean IsDoorOpen() {

 if (digitalRead(DoorSensePin) == 1) { return 1; }
 if (digitalRead(DoorSensePin) == 0) { return 0; }  

}

 void Unlock()
 {
   myServo.write(unlockedPosition);
   delay(100);
   WaitToLock();
 }
 
 void Lock()
 {
   myServo.write(lockedPosition);
 }
 

//This function will loop until the door is closed for 5 seconds and then Lock. void WaitToLock() { BeginWaitingToLock:

  while (IsDoorOpen() == 1)  { /* Serial.println("Door Needs to Close.");    /* do nothing */ }  
  //At this point Door should have shut
  Serial.println("Door has been shut! Waiting 5 seconds.");
  delay(1000 * 5); //wait 5 seconds
  if (IsDoorOpen() == 0) // if door is still closed after delay, then lock
  {
     Lock(); 
  }
  if (IsDoorOpen() == 1) 
  { 
    Serial.println("Door Did not remain shut.  Starting over loop.");
    goto BeginWaitingToLock;
  }  
  

}