Question

Exercise 10.2.5: Setting the threshold for biometrics.

A biometric authentication system using fingerprints returns a value between 0 and 1 for each attempted match. The system was tested with 1000 genuine fingerprints and 1000 imposter fingerprints. The histogram shows the numbers of genuine and imposter attempts for different ranges.
Ex: 88 of the 1000 genuine fingerprints returned a value of n between 0.5 and 0.4, while only 3 imposter fingerprints returned a value in the same range.

Range of n	Genuine fingerprints	Imposter fingerprints
1 ≥ n > 0.9	192	0
0.9 ≥ n > 0.8	188	0
0.8 ≥ n > 0.7	176	0
0.7 ≥ n > 0.6	158	0
0.6 ≥ n > 0.5	133	1
0.5 ≥ n > 0.4	88	3
0.4 ≥ n > 0.3	49	5
0.3 ≥ n > 0.2	15	29
0.2 ≥ n > 0.1	1	319
0.1 ≥ n > 0	0	643

(a)

Determine the threshold value of n such that less than 1% of imposter attempts are accepted. How many false alarms are generated as a result?

(b)

Determine the threshold value of n such that less than 1% of genuine attempts are rejected. How many imposter attempts are accepted as a result?

(c)

Determine the threshold value of n such that no genuine attempts are rejected. How many imposter attempts are accepted as a result?

Answer 1

ANS : a)

In this fingerprint attendance system circuit, we used Fingerprint Sensor module to authenticate a true person or employee by taking their finger input in the system. Here we are using 4 push buttons to enroll, Delete, UP/Down. ENROLL and DEL key has triple features. ENROLL key is used for enrollment of a new person into the system. So when the user wants to enroll new finger then he/she need to press ENROLL key then LCD asks for the ID, where user want to be store the finger print image. Now if at this time user does not want to proceed further then he/she can press ENROLL key again to go back. This time ENROLL key behave as Back key, i.e. ENROLL key has both enrollment and back function. Besides enroll key is also used to download attendance data over serial monitor. Similarly, DEL/OK key also has the same double function like when user enrolls new finger, then he/she need to select finger ID by using another two key namely UP and DOWN. Now user need to press DEL/OK key (this time this key behave like OK) to proceed with selected ID. And Del key is used for reset or delete data from EEPROM of Arduino.

AND :b)

We have 1023 byte memory in Arduino UNO out of which we have 1018 byte to store data and we have taken 5 user attendance data for 30 days. And every attendance will record time and date so this becomes 7-byte data.

So total memory required is

5*30*7=1050     so here we need more 32 bytes

But if we will use 4 users then we required

4*30*7=840

Here we have done this project demonstration by taking 5 users memory. By this, we will not able to store 32 byte or 5 attendance records of the 5^th user.

You may try it by 4 users by changing some lines in code. I have made the comments in the code where the changes are needed.

ANS :c)

After it, we have to write code for downloading attendance data.

SMALL CODE :

void setup()
{
    delay(1000);
    lcd.begin(16,2);
    Serial.begin(9600);
    pinMode(enroll, INPUT_PULLUP);
    pinMode(up, INPUT_PULLUP);
    pinMode(down, INPUT_PULLUP);
    pinMode(del, INPUT_PULLUP);
    pinMode(match, INPUT_PULLUP);
    pinMode(buzzer, OUTPUT);
    pinMode(indFinger, OUTPUT);
    digitalWrite(buzzer, LOW);
    if(digitalRead(enroll) == 0)
    {
      digitalWrite(buzzer, HIGH);
      delay(500);
      digitalWrite(buzzer, LOW);
      lcd.clear();
      lcd.print("Please wait");
      lcd.setCursor(0,1);
      lcd.print("Downloding Data");

                                                          THANKS :)