What is biometric authentication?

Biometric authentication is a type of security that is inherently linked to an individual user. It is used to verify that a person is who they present themselves to be.  

Biometric authentication is employed to control access resources, which can include physical structures, such as buildings or rooms, and digital devices, such as laptops and servers.

The effectiveness of biometric authentication depends on the supporting technology’s ability to recognize and match biometric data accurately. This can be influenced by various factors, including the quality of the initial enrollment, changes to the biometric trait over time (e.g., aging and injuries), and the environmental conditions during capture (e.g., lighting for facial recognition and background noise for voice recognition). 

With biometric authentication, data points related to the unique biological characteristics of an individual are collected and used to verify their identity. These physical or behavioral traits are stored data referred to as a biometric template. 

Biometric authentication compares one or more registered or enrolled biometric data points (e.g., fingerprint, facial pattern, iris, or voice) with a newly captured biometric sample of the same type from an individual attempting to gain access to a system or device. The process of biometric authentication involves four main stages. 

  1. Enrollment 
    This is the initial step where an individual’s biometric authentication data is captured, processed by an algorithm, and stored in a secure database.  

    During enrollment, a biometric sensor scans the individual’s unique biological trait (e.g., a fingerprint scanner capturing a fingerprint). The data from this scan is processed by software that extracts distinguishing features, which are then converted into a digital format known as a biometric template.  

    Personal identifiers can also link to biometric templates to provide other vectors to validate the identity of the individual. 
  2. Capture 
    When access is attempted, the biometric authentication system captures the individual’s biometric data again. This real-time or live data is then processed to create a temporary digital representation. 
  3. Comparison
    The newly captured biometric data is compared to the stored biometric templates in the database. This comparison involves sophisticated algorithms that evaluate the degree of similarity between the live biometric scan and the enrolled biometric templates. This analysis is used to assess whether the new biometric scan matches any of the stored biometric templates to a high enough degree to be considered the same person. 
  4. Decision
    The biometric authentication system makes a decision based on the comparison. If the biometric sample matches a stored template within predefined thresholds, the authentication is successful, and access is granted. If there is no match found for live biometric data in the database or if the similarity is below the threshold, access is denied. 

Types of biometric authentication

The following are several types of biometric authentication. Each of these utilizes scanners or sensors to capture biometric data in a digital format to create a biometric template and for subsequent scans to be used to assess matches of live data with stored information. 

Behavioral biometrics

This includes behavioral traits that are unique to an individual, including: 

  • Gait analysis—the way a person walks 
  • Signature recognition—the signature’s static shape, along with other factors, such as speed, pressure applied, and stroke order  
  • Typing recognition—how someone types, including how fast they type 

Chemical biometrics

Chemical biometrics identifies individuals based on their unique biochemical traces, using methods like scent analysis, skin oil composition analysis, DNA analysis, sweat analysis, or breath analysis.   

Ear recognition

Ear recognition analyzes the unique shape, size, and structure of an individual’s ears. 

Facial recognition

Facial recognition captures unique facial geometry features, such as the distance between the eyes or the shape of the cheekbones. Eighty nodal points on a human face are combined to create a faceprint for biometric authentication.   

Fingerprint recognition

Fingerprint recognition identifies an individual based on the ridges and valleys on their fingertips, which have a unique pattern.  

Hand geometry

Hand geometry measures the shape and size of a person’s hand, including length, width, thickness, and surface area, as well as the valleys between knuckles.   

Iris recognition

Iris recognition uses the highly detailed, unique nature of an individual’s iris (i.e., the colored ring around the pupil). It highlights the intricate structures that make up a unique pattern of a person’s iris, which remains stable over time.

Retinal scans

Retinal scans use the unique pattern of blood vessels at the back of an individual’s eyes.

Vein or vascular recognition

Vein or vascular recognition identifies the unique patterns of blood vessels beneath the skin’s surface. It is usually used on fingers, palms, or the back of hands. 

Voice recognition

Voice recognition analyzes the unique features of a person’s voice, including pitch, tone, and cadence created by the shape of a person’s throat and mouth. This type of biometric authentication is commonly used in systems that require verbal commands or for user authentication

Multimodal biometric authentication

Multimodal biometric authentication refers to the biometric authentication process that integrates two or more biometric identifiers to verify an individual’s identity. This approach combines two or more types of biometric data, such as fingerprints, retinal scans, iris scans, voice recognition, and vein or vascular recognition.  

The objective of multimodal biometric authentication is to reduce the likelihood of false matches. It is used to create a more robust biometric authentication profile by leveraging the strengths and compensating for the weaknesses of individual biometric modalities.   

Implementing multimodal biometric authentication systems can pose some challenges. They often require more complex hardware and software that is often complicated to integrate, leading to increased costs. The need for multiple biometric inputs can also make the authentication process longer, potentially impacting user convenience. In addition, multimodal systems may raise privacy concerns, as they require the collection and storage of sensitive biometric data. 

Biometric authentication benefits

  • Access without remembering credentials 
  • Actions can be traced back to the individual who performed them, creating auditable records of access and transactions    
  • Difficulty in replicating biometric traits 
  • Easy for users to use 
  • Fast authentication  
  • Minimized risk of unauthorized access  
  • Non-transferable authentication method 
  • Precise identification and verification of identities 
  • Reduced chances of identity theft and fraud  
  • Streamlines authentication process   

Biometric authentication challenges

The following challenges highlight the need for careful consideration and robust safeguards when implementing biometric authentication to mitigate potential risks

Data security risks

Despite security precautions, compromises can occur through insider threats or cyber attacks, putting biometric data at risk. 

Ethical issues

Biometric authentication systems cannot be relied upon to avoid the potential for discriminatory practices or bias, particularly those involving facial recognition technologies. 

False positives and negatives

Inaccuracies in biometric systems can result in false positives that allow unauthorized access or deny access to legitimate users through false negatives. 

High implementation costs

Deploying biometric authentication systems can be expensive due to the cost of infrastructure, including specialized hardware and software. 

Inclusivity and accessibility

Not all individuals can use certain biometric modalities due to physical disabilities or the absence of specific biometric traits. For example, fingerprint scanners may not work for people with certain skin conditions, and facial recognition systems may struggle with certain ethnicities or with people who wear glasses or other facial coverings. 


It is difficult to ensure compatibility and standardization across different biometric authentication systems and technologies. 

Legal and regulatory challenges

Biometric data is subject to several regulations, which can complicate the implementation of these systems, especially in international contexts. Among the many laws that regulate the collection, use, and storage of biometric data are the European Union’s General Data Protection Regulation (GDPR) and the California Consumer Privacy Act (CCPA). 

Permanent compromise

Unlike passwords, biometric characteristics cannot be changed once compromised, posing long-term security risks related to permanent compromises. 

Privacy concerns

The collection and storage of biometric data puts personally identifiable information (PII) at risk of misuse, including unauthorized data sharing, profiling, and surveillance. 

Technical limitations

Environmental factors, sensor quality, and changes in biometric traits over time can affect the reliability of biometric systems. 

User acceptance

There is a level of resistance from users who are uncomfortable with providing biometric data due to privacy concerns or dislike of the technology. 

Biometric authentication vs passwords

Biometric authentication and passwords represent two fundamentally different approaches to securing access to systems, devices, and data. While passwords rely on knowledge-based mechanisms, biometric authentication leverages the physiological or behavioral characteristics of individuals.   

Biometric authentication Passwords 
Biometric authentication identifies and verifies individuals based on inherent physical or behavioral traits, such as fingerprints or voice waves.    

Considerations with biometric authentication: 
-Raises significant privacy issues because it cannot be replaced
-Does not accommodate users with physical conditions or disabilities that affect their biometric traits    
Passwords are a form of authentication that requires users to input a secret word, phrase, or string of characters to gain access to protected systems or applications.     

Considerations with passwords: 
-Avoids privacy issues because it can be easily changed if compromised  
-Uses widely used and understood methodology that does not require special hardware for implementation    

Biometric authentication FAQ

The following are several frequently asked questions related to biometric authentication. 

Is biometric authentication an invasion of users’ privacy?

Biometric authentication has gained significant traction but has raised substantial privacy concerns. This is because biometric data is intrinsically linked to an individual’s personal identity. The primary concern revolves around the irreversible nature of biometric data and the fact that once compromised, unlike a password, it cannot be altered or reissued.  

Data breaches involving biometric information can have far-reaching consequences for individuals, including identity theft and unauthorized tracking. The storage and processing of biometric data pose additional privacy concerns. In addition, biometric authentication requires users to provide their unique biological traits, which some may view as an invasion of their privacy.   

Can a photograph or still video image be used for biometric authentication?

Yes, a photograph or still video image can indeed be used for biometric authentication, specifically in facial recognition systems. Advanced algorithms process these characteristics from photographs or video frames to match them against a database of authorized identities.  

This approach raises concerns about accuracy since images can be captured without consent and used to gain unauthorized access. 

What are some biometric authentication use cases?

Biometric authentication technology is used across various sectors, including: 

  • Banking and financial services—fingerprints, facial recognition, and voice authentication are used to access banking services and secure transactions  
  • Border control and immigration—iris scans, facial recognition, and fingerprints are used at airports and border crossings   
  • Law enforcement—fingerprints and DNA are used to identify suspects, victims, and persons of interest  
  • Mobile device security—fingerprints and facial recognition are used to unlock devices and authenticate users  
  • Workplace access control—biometric systems to ensure secure access to buildings, offices, and sensitive areas 

What is the difference between biometric authentication and verification?

Biometric authentication and verification are closely related concepts that are often used interchangeably but serve distinct purposes and operate under different premises. Both methods leverage biometric data for security purposes but are tailored to fit different security and access requirements. 

Biometric authentication, often referred to as identification or one-to-many matching, involves identifying an individual among many by comparing their biometric data against multiple records in a database. This process is used in scenarios where the system needs to establish who the person is from a large set of possible identities without the person claiming an identity upfront. Authentication answers the question, “Who is this person?” 

Biometric verification is a one-to-one comparison process used to confirm an individual’s claimed identity. It involves matching the person’s biometric data against a specific biometric template previously stored in the system. Verification answers the question, “Is this person who they claim to be?” 

The identity verification toolbelt

Biometric authentication is one of many tools in security practitioners’ identity toolbelt, including passwords or other access management systems. It is important to remember that how identities are managed and controlled is an important consideration when evaluating biometric authentication or other authentication solutions. 

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