Biometric system

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Fingerprints form before birth and, except for cuts resulting in permanent scars and diseases such as leprosy, remain unchanged until the body decomposes after death.
Fingerprint evidence is the most positive investigative means of identifying people. Even DNA blood analysis cannot differentiate between identical twins - fingerprints can. Every fingerprint is unique. Fingerprints are records of the raised surface of papillary skin, also called friction skin, appearing on the pal mar side of a person's fingers.

Papillary skin is present on the pal mar surfaces of the hands and the plantar surfaces of the feet. These are skin surfaces on your fingers and hands which touch a drinking glass with when you pick it up, and the skin surfaces on your toes and bottoms of your feet which touch the ground when you walk barefoot.

Palm, lower finger joint, sole and toe impressions are all unique. Almost any area of friction skin that can be covered with a pencil eraser is large enough to permit positive identification if recorded clearly and completely.

Although many fingerprints have the same pattern type and look very similar, when examined closely the differences can prove that the prints have been made by different fingers. And the opposite may be true. Prints from the same finger may look different because the pressure used to make them differed. Or they may look different because the curve of the surface differed. Yet examination by a qualified examiner can prove the prints to have been made by the same finger.

Positive identification or elimination of fingerprints can only be made by trained and qualified fingerprint examiners. Examiners identify prints by making the qualitative and quantitative comparisons of one friction ridge print with another. They compare the separate ridge characteristics and their relationship one to another. They can do this from impressions of any area of friction skin.

Fingerprint records are maintained in civil and criminal repositories in America. Civil fingerprint identification, such as occurs with police or soldiers entering into public service, is the recording of a person's fingerprints primarily for the purposes of:

• Determining the person has no prior criminal arrest record
• Verifying the person's identity at a later date
• Criminal fingerprint identification is the recording of an arrested person's fingerprints

Primarily for the purposes of:

• Recording the arrest and/or conviction information in a permanent file associated with that person
• Determining the person's true identity if they have used other names for previous arrests
• Determining the person's prior arrest/conviction record

Why Fingerprints?

With increasingly urgent need for reliable security, biometrics is being spotlighted as the authentication method for the next generation. Among numerous biometric technologies, fingerprint authentication has been in use for the longest time and bears more advantages than other biometric technologies do.

Fingerprint authentication is possibly the most sophisticated method of all biometric technologies and has been thoroughly verified through various applications. Fingerprint authentication has particularly proved its high efficiency and further enhanced the technology in criminal investigation for more than a century.

Even features such as a person's gait, face, or signature may change with passage of time and may be fabricated or imitated. However, a fingerprint is completely unique to an individual and stayed unchanged for lifetime. This exclusivity demonstrates that fingerprint authentication is far more accurate and efficient than any other methods of authentication.

Also, a fingerprint may be taken and digitalized by relatively compact and cheap devices and takes only a small capacity to store a large database of information. With these strengths, fingerprint authentication has long been a major part of the security market and continues to be more competitive than others in today's world.

History of Fingerprint Technology

The beginning of fingerprints goes back to as early as the ancient times. According to historical findings, fingerprints were used on clay tablets for business transactions in ancient Babylon. In China, thumb prints were found on clay seals. But it was in the 19th century that the results of scientific studies were published and fingerprint technology began to be considered more seriously.

Using the1800's scientific studies as a foundation, fingerprint technology was already in use by the beginning of the 20th century. In 1924, FBI(Federal Bureau of Investigation) is already known to have maintained more than 250 million civil files of fingerprints for the purpose of criminal investigation and the identification of unknown casualties. In the late 1960's, fingerprint technology met a great turning point when it gave birth to 'live-scan,' a method to obtain a fingertip image without the use of print ink. When the FBI announced that it planned to stop using paper fingerprint cards inside their new Integrated AFIS (IAFIS) site, it was actually announcing the remarkable breakthrough of today's live-scan technology.

But fingerprint identification technology did not stop as a forensic method only. It was officially used for business purposes in 1968 at one security corporation in Wall Street. Fingerprints are now being used as a secure and effective authentication method in numerous fields, including financial, medical, e-commerce and entrance control applications. Modern applications of fingerprint technology rely in large part on the development of exceptionally compact fingerprint sensors.

Fingerprint Identification Process

Fingerprint identification process consists of two essential procedures: enrollment and authentication. Taking the following steps completes each procedure:

Input Fingerprint


image Acquisition > feature Extraction > template(s) > Matching > template(s)


image Acquisition > feature Extraction > Matching > template(s)

As shown in the Input Fingerprint above, fingerprint identification system compares the input fingerprint image and previously registered data to determine the genuineness of a fingerprint. All the steps described above affect the efficiency of the entire system, but the computational load of the following steps can be reduced to a great extent by acquiring a good-quality fingerprint image in the first step.

Real-time image acquisition method is roughly classified into optical and non-optical. Optical method relies on the total reflection phenomenon on the surface of glass or reinforced plastic where the fingertip is in contact. The sensor normally consists of an optical lens and a CCD module or CMOS image sensor. In contrast, semiconductor sensors, as a typical example of non-optical sensors, exploit electrical characteristics of a fingertip such as capacitance. Ultrasonic wave, heat, and pressure are also utilized to obtain images with the non-optical fingerprint sensors. Non-optical sensors are said to be relatively more suitable for massive production and size reduction such as in the integration with mobile devices. Detailed comparison is found in Table 1

Optical Non-optical
Measuring Method light pressure, heat, capacitance, ultrasonic wave
Strength highly-stable performance
physical/electrical durability
high-quality image low cost with mass production compact size integrated with low-power application
Weakness relatively high cost
limit to size-reduction
relatively easy to fool with a finger trace or fake finger physical/electrical weakness
performance sensitive to the outer environment(temperature, dryness of a finger)
Application entrance, time, and attendance control
banking service
PC security PC security
e-commerce authentication
mobile devices & smart cards

Feature Extraction

There are two main ways to compare an input fingerprint image and registered fingerprint data. One is to compare an image with another image directly. The other is to compare the so-called 'features' extracted from each fingerprint image. The latter is called feature-based/minutia-based matching. Every finger has a unique pattern formed by a flow of embossed lines called “ridges” and hollow regions between them called “valleys.” As seen in the Picture 2 below, ridges are
represented as dark lines, while valleys are bright.


The matching step is classified into 1:1 and 1:N matching according to its purpose and/or the number of reference templates. 1:1 matching is also called personal identification or verification. It is a procedure in which a user claims his/her identity by means of an ID and proves it with a fingerprint. The comparison occurs only once between the input fingerprint image and the selected one from the database following the claim by the user.

On the contrary, 1:N matching denotes a procedure where the system determines the user's identity by comparing the input fingerprint with the information in the database without asking for the user's claim. A good example of this is AFIS(Automated Fingerprint Identification System) frequently used in criminal investigation.

The output result of the matching step is whether or not the input fingerprint is identical to the one being compared in the database. Then how could the accuracy of the matching procedure be represented in number? The simplest measures are FRR(False Reject Rate) and FAR(False Accept Rate). The former is the rate of genuine user's rejection and the latter is the rate of impostor's acceptance.

Fingerprint Application

Markets for fingerprint technology include entrance control and door-lock applications, fingerprint identification mouses, fingerprint mobile phones, and many others. The fingerprint markets are classified as follows:

1, Physical Access
Door Lock Entrance Control

2, Network Access(non- Mobile)
Sensing Terminat
Smart card

3, Mobile Access
Cell Phone

As the advanced technology enables even more compact fingerprint sensor size, the range of application is extended to the mobile market. Considering the growing phase of the present mobile market, its potential is the greatest of all application markets.

Recording Inked Prints

Fingerprints impressions taken directly from a person's fingers for the purpose of identification must be uniformly clear and visible. It is not hard to take good, clear fingerprints. A good fingerprint impression is dark gray in color and free of smudges. All that is needed to obtain good prints is practice.

Have the subject sign the fingerprint card. It is not needed nor desired that you advise persons of their legal rights just to take their fingerprints. Have the subject wash his hands to remove any dirt particles. Make sure that the fingers are free of lint from the towels used to dry the hands. Gather your equipment together and ready it for printing.

In addition to fingerprint cards, you will need--
• A fingerprint card holder.
• Ink (printer's ink or any special fingerprint ink).
• A rubber ink roller.
• Glass (or metal) plate (approximately 12" x 6" x l", fixed to a base).

• Note:

your counselor may provide an inkless chemical recording method, porelon ink pad, or even a computerized live scan device for recording the fingerprints. The mechanics of recording the fingers to make the record prints will be similar and the resulting fingerprint card will look somewhat similar regardless of the method used to completely and legibly record the fingerprints.

Place a small dab of ink on the plate glass and roll until a thin, even film covers the surface. If using a glass plate, it helps to place a white card underneath to check the ink's thickness while rolling it out and while inking fingers. Secure the fingerprint card in the holding device, and the equipment is ready to use.

The steps for inking fingers and the steps for making impressions on the card are the same. Each finger is rolled through the ink on the glass and then that finger impression is rolled on the fingerprint card. All rolling should be made in single movements. Do not roll back and forth. The pressure should be just enough to apply an even coat of ink on the finger and a clear image on the card.

After the procedure is complete, fill in the data on the fingerprint card. Sign the card or paper for identification. This signature is important in legal proceedings.


one-fourth inch below the first joint. They are made by rolling the finger or thumb from nail edge to nail edge. This surface gives all the needed ridge characteristics for correct classification. (Classification is the means by which a set of fingerprints may be filed and then retrieved in the future.)

There is a specific means of rolling the subject's fingers or thumbs in the ink and on the fingerprint card to give a good impression. You roll the fingers or thumbs from "awkward to comfortable." To see what is meant, hold your hands in front of you with the backs of your hands together. Now roll them around so that the palms are together and thumbs are up. You will see that the right hand moved clockwise and the left hand counterclockwise. This is the direction the fingers on each hand should be moved. Thumbs are moved in the opposite direction of the fingers.

When you take prints, grasp the top of the subject's hand to make sure that the finger to be printed is extended. The roll is a single movement and with only enough pressure to give a clear print. Tell the subject to look away from the fingerprint card and to try not to "help" the roll. This will reduce smudging and give a clean impression.


Plain impressions verify the order of the rolled impressions and show characteristics that are sometimes distorted in rolled prints. Plain impressions are made on the card by just pressing the four inked fingers on the card at a slight angle. They should show from the tips to one-fourth inch below the first joint. Thumbs are then printed by inking and pressing them on the block next to the plain finger impressions.

Have the subject hold his fingers straight and stiff. The hand should be level with the wrist. Grasp the wrist with one hand and press the fingers onto the cards with the other hand. Then allow the subject to clean the ink from his fingers.


Excessive perspiration may cause inked impressions of many persons to blur. Wipe each finger with a cloth and then quickly ink and roll it on the fingerprint card. Follow this process with each finger. You may also wipe the fingers with alcohol or other drying agent. Some people have dry, rough hands from their work. Rubbing the tips of the fingers with oil or creams can often make them soft enough for clear, un-smudged prints. If the ridges are fine and small and the skin is soft, holding ice against the fingers sometimes helps.

If the hands and fingers are deformed, normal printing steps cannot be followed. Apply the ink directly to the fingers with a spatula or small roller. Then rotate a square piece of paper around the finger. When an acceptable print has been made, the square is taped to the proper box of the fingerprint card. If there is an extra finger (usually a "little" finger or a thumb), the innermost five are printed as usual on the card. The extra digit is then printed on the reverse of the card. Print webbed fingers as well as you can in the rolled and plain impressions. And if a finger or a fingertip is amputated, note that fact in the proper box.


Experts with years of specialized training, experience and proven ability (proficiency tested) can positively identify persons using fingerprints by comparing various levels of detail present in the known fingerprints (on file) and questioned fingerprints (of the person just printed). Positive identification occurs when a qualified expert determines that the questioned and known prints contain sufficient quality (clarity) and quantity of friction ridge detail in agreement with no unexplainable differences. Because the skin on fingers and palms is very flexible, no two fingerprints (even one recorded immediately after another) are exactly alike. Fingerprint experts study for years to understand the normal variations caused by flexible skin, by finger movement, by temporary skin damage, and by other factors such as dirt or liquid present on a finger or surface. Even one unexplainable difference means that the fingerprints are not from the same person.

There is no minimum number of matching points (Level 2 detail) required for positive identification because fingerprint experts also use the actual ridge shapes (Level 3 detail) during the identification process. Because Levels 1, 2 and 3 are used, the amount of area required to effect an identification, such as just a portion of one fingerprint, depends on the quality (clarity) and quantity of friction ridge detail present in the questioned and known prints being compared. In many situations, a tiny piece of a fingerprint with good quality ridge detail from a crime scene may be positively identified. At other times, the poor quality of a fax machine copy of a complete set of ten rolled ink fingerprints may preclude them from being identified.

Positive identification means that a qualified expert has determined the fingerprints were made by one specific person to the exclusion of everyone else in the world.


When wrapping presents, you may have sometimes noticed that your fingerprints show up on the sticky side of the tape if you have any dirt (or discoloration from the wrapping paper) on your fingers. Using the same type of clear, cellophane tape you can record fingerprints that often have better quality (clarity) detail than inked or electronic prints.

First make the finger(s) to be printed "dirty" by rubbing it against pencil lead, a charcoal drawing stick, a charcoal briquette or even against black ink newspaper photos. Next, place the sticky side of the cellophane tape against the "dirty" fingers one at a time and then stick the tape to a piece of white paper or cardboard. Label each strip to indicate which finger/thumb and hand it is from. Record all ten fingers/thumbs on a piece of paper to show to your counselor (requirement 4 for Fingerprinting Merit Badge).

Fingerprints produced by clear tape lifts are mirror image reversals of fingerprints produced using ink and paper. If you use white (opaque) tape to lift the prints from the fingers and then stick the tape to a clear plastic document protector, the fingerprints viewed through the clear plastic will be in the same relative position as inked prints.

Look at the tape-lift fingerprints through a magnifying glass and you will see very fine friction ridge detail, including very exact ridge shapes and pore structure that is often not recorded by ink or electronic fingerprint recording methods (especially when recording detail from small children's fingers). If you record your own fingerprints using tape, you can use a magnifying glass to determine your own fingerprint patterns (requirement 5 for Fingerprinting Merit Badge).


Automated fingerprint identification systems (AFIS) were developed by police as a means of identifying a person from a very large fingerprint record file such as the FBI's over 40-million-person repository. Biometric fingerprinting was developed by businesses as a replacement for passwords, ID cards or other methods of controlling access to computers or access to buildings/rooms/areas.

AFIS involves positive identification and was developed by police to identify persons who often desire to not be identified. Biometrics normally does not involve positive identification, but instead involves a computer finding enough similarity to give a red light (asking you to try placing your finger again) or green light (your finger matches close enough) to enable access. Biometrics is normally used as a means to identify persons who want to be identified (who want fast, routine access to a computer/building/area, etc.) and thus it is okay that biometric systems often fail to correctly recognize a finger and require the person to "try again" (place the finger on the reader again). Such failure to identify fingers in law enforcement AFIS systems is unacceptable and could have serious negative consequences such as letting a criminal remain unidentified.

Biometric ATMs for rural India

To reach the rural masses, banks are going all out in providing a user-friendly banking experience. To boost micro financing initiatives, banks are deploying biometric solutions with ATMs. Establishing the identity of a rural depositor through biometrics makes it possible for illiterate or barely literate folks to become part of the banking user community. In recent years the importance of biometrics has grown tremendously with an increasing demand of security in accordance of unique identification of individuals. Its use for identification in applications other than policing is on the rise. In view of the rapidly increasing applications, the scope of biometrics is also increasing, be it identification via face, voice, retina or iris. Fingerprinting, however, has the advantage of being a familiar concept worldwide.
In the retail payments arena, developments in biometric technology have made their presence felt in the pervasiveness of self service devices including Automated Teller Machines (ATMs) and Point of Service (POS) machines. Some of the new generation POS terminals are biometric enabled with smart card readers, allowing thumb-print based authentication. Some Indian banks have started implementing biometric applications in retail branch applications for officer authentication. Elsewhere in the world, efforts are on enabling payments through kiosks based on fingerprints (non-card based). ATM enhancements with biometric support envisaged by vendors eliminate the need for PIN entry, and authenticate customer transactions by thumb-impressions. A simplified menu on ATMs coupled with possible audio guidance in local language enable easy use for rural masses. So far bank ATMs are dependent on PIN verification. The fingerprint authentication method is non-PIN based, and this requires enhancements to the standard Switch environment.

Securing transactions with fingerprints

With the development of biometric solutions for the ATMs there is no need to remember PIN numbers. Software vendors are coming up with finger print solutions for the rural masses.

Customers opting for biometric authentication can visit a nearby kiosk or ATMs or bank, where his finger-print data would be scanned into a special PC with a finger-print scanner and the scanned fingerprint is then stored in an encrypted form in a central server. When a customer inserts (or swipes) his card in a biometric enabled ATM, he is prompted to set his finger in the fingerprint scanner. The transaction along with customer's biometric information is passed on to the switch. The switch verifies the fingerprint with the server, and if successful, requests the banking application to authorize the transaction.

Benefits of Biometric supported ATMs

• Provides strong authentication
• Can be used instead of a PIN
• Hidden costs of ATM card management like card personalisation, delivery, management, re-issuance, PIN generation, help-desk, and re-issuance can be avoided
• Ideal for Indian rural masses
• It is accurate
• Flexible account access allows clients to access their accounts at their convenience
• Low operational cost of the ATMs will ultimately reduce TCO

How it works

With ATMs supported by biometric solutions, banks having a presence across the country are leveraging on this technology. The ATMs are networked and connected to a centralised computer (Switch), which controls the ATMs. The use of biometrics identification is possible at an ATM. The information can be stored at a bank branch. ATMs are so prevalent and you have so many people using ATMs that it becomes easy to use biometrics as a replacement for an ATM PIN. The typical ATM has two input devices (a card reader and keypad) and four output devices (display screen, cash dispenser, receipt printer, and speaker). Invisible to the client is a communications mechanism that links the ATM directly to an ATM host network. The ATM functions much like a PC, it comes with an operating system (usually OS/2) and application software for the user interface and communications.

While most ATMs use magnetic strip cards and personal identification numbers (PINs) to identify account holders, other systems may use smart cards with fingerprint validation. The ATM forwards information read from the client's card and the client's request to a host processor, which routes the request to the concerned financial institution. If the cardholder is requesting cash, the host processor signals for an electronic funds transfer (EFT) from the customer's bank account to the host processor's account. Once the funds have been transferred, the ATM receives an approval code authorising it to dispense cash. This communication, verification, and authorisation can be delivered in several ways. Leased line, dial-up or wireless data links may be used to connect to a host system, depending on the cost and reliability of the infrastructure. The host systems can reside at a client's institution or be part of an EFT network. The EFT network supports the fingerprint authentication. Point-of-sale services that use biometric solutions are also possible.

The FSS Biometric ATM Solution consists of a central server which holds a repository of customer fingerprints. It also customises the Switch to enable authorisation of a customer's biometric data and interfaces with ATMs enabled with biometric devices as per FSS specifications. The central server solution is platform independent, it uses Java and can run on Unix and Oracle/ Microsoft SQL Server, customisation to BASE24 Switch (of which FSS is the distributor) is done using TAL. Biometric application and devices from Secugen are used for customer interface and application development.