If you’re planning to take the SY0-501 exam, you should have a good understanding of identity and access management concepts. This includes authentication factors such as the something you are authentication factor that uses biometrics for authentication.
For example, can you answer this practice test question?
Q. Your organization has decided to implement a biometric solution for authentication. One of the goals is to ensure that the biometric system is highly accurate. Which of the following provides the BEST indication of accuracy with the biometric system?
A. The lowest possible FRR
B. The highest possible FAR
C. The lowest possible CER
D. The highest possible CER
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation are available at the end of this post.
The something you are authentication factor uses biometrics for authentication. Biometric methods are the strongest form of authentication because they are the most difficult for an attacker to falsify. In comparison, passwords are the weakest form of authentication.
Biometric Methods
Biometrics use a physical characteristic, such as a fingerprint, for authentication. Biometric systems use a two-step process. In the first step, users register with the authentication system. For example, an authentication system first captures a user’s fingerprint and associates it with the user’s identity. Later, when users want to access the system, they use their fingerprints to prove their identity. There are multiple types of biometrics, including:
• Fingerprint scanner. Many laptop computers include fingerprint scanners or fingerprint readers, and they are also common on tablet devices and smartphones. Similarly, some USB flash drives include a fingerprint scanner. They can store multiple fingerprints of three or four people to share access to the same USB drive. Law enforcement agencies have used fingerprints for decades, but they use them for identification, not biometric authentication.
• Retina scanner. Retina scanners scan the retina of one or both eyes and use the pattern of blood vessels at the back of the eye for recognition. Some people object to the use of these scanners for authentication because they can identify medical issues, and because you typically need to have physical contact with the scanner.
• Iris scanner. Iris scanners use camera technologies to capture the patterns of the iris around the pupil for recognition. They are used in many passport-free border crossings around the world. They can take pictures from about 3 to 10 inches away, avoiding physical contact.
• Voice recognition. Voice recognition methods identify who is speaking using speech recognition methods to identify different acoustic features. One person’s voice varies from another person’s voice due to differences in their mouth and throat, and behavioral patterns that affect their speaking style. As an example, Apple’s Siri supports voice recognition. After setting it up, Siri will only respond to the owner’s voice. Unfortunately, that does prevent the old party trick of yelling out “Hey Siri” at a party where multiple people have iPhones.
• Facial recognition. Facial recognition systems identify people based on facial features. This includes the size of their face compared with the rest of their body, and the size, shape, and position of their eyes, nose, mouth, cheekbones, and jaw. A drawback with this is that it is sometimes negatively affected by changes in lighting. Microsoft Windows systems support Windows Hello facial recognition services. To avoid the challenges from normal lighting, it uses infrared (IR) and can operate in diverse lighting conditions.
Biometric Errors
Biometrics can be very exact when the technology is implemented accurately. However, it is possible for a biometric manufacturer to take shortcuts and not implement it correctly, resulting in false readings. Two biometric false readings are:
• False acceptance. This is when a biometric system incorrectly identifies an unauthorized user as an authorized user. The false acceptance rate (FAR, also known as a false match rate) identifies the percentage of times false acceptance occurs.
• False rejection. This is when a biometric system incorrectly rejects an authorized user. The false rejection rate (FRR, also known as a false nonmatch rate) identifies the percentage of times false rejections occur.
True readings occur when the biometric system accurately accepts or rejects a user. For example, true acceptance is when the biometric system accurately determines a positive match. In contrast, true rejection occurs when the biometric system accurately determines a nonmatch.
Biometric systems allow you to adjust the sensitivity or threshold level where errors occur. By increasing the sensitivity, it decreases the number of false matches and increases the number of false rejections. In contrast, decreasing the sensitivity increases the false matches and decreases the false rejections. By plotting the FAR and FRR rates using different sensitivities, you can determine the effectiveness of a biometric system.
The figure shows the crossover error rate (CER) for two biometric systems. The CER is the point where the FAR crosses over with the FRR. A lower CER indicates that the biometric system is more accurate. For example, the system represented with the solid lines in the figure is more accurate than the system represented by the dotted lines.
Crossover error rate
Remember this
The third factor of authentication (something you are, defined with biometrics) is the strongest individual method of authentication because it is the most difficult for an attacker to falsify. Biometric methods include fingerprints, retina scans, iris scans, voice recognition, and facial recognition. Iris and retina scans are the strongest biometric methods mentioned in this section, though iris scans are used more than retina scans due to the privacy issues and the scanning requirements. Facial recognition is the most flexible and when using alternate lighting (such as infrared), they might become the most popular. The crossover error rate (CER) measures the accuracy of a system and lower CERs are better.
Q. Your organization has decided to implement a biometric solution for authentication. One of the goals is to ensure that the biometric system is highly accurate. Which of the following provides the BEST indication of accuracy with the biometric system?
A. The lowest possible FRR
B. The highest possible FAR
C. The lowest possible CER
D. The highest possible CER
Answer is C. A lower crossover error rate (CER) indicates a more accurate biometric system.
The false acceptance rate (FAR) and the false rejection rate (FRR) vary based on the sensitivity of the biometric system and don’t indicate accuracy by themselves.
A higher CER indicates a less accurate biometric system.
See Chapter 2 of the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide for more information on authentication factors.