Biometrics

Identifying someone by a physical trait, such as their face, voice, or fingerprint.

For example, a phone that unlocks with a fingerprint or a face scan is using biometrics, and so is a verification flow that compares a selfie with the photo on an ID.

Automated recognition of individuals based on measurable behavioral or physiological characteristics.

Biometric traits fall into two groups:

• Physiological traits are features of the body, such as the face, fingerprint, or iris.
• Behavioral traits are patterns in how a person acts, such as typing rhythm or how they hold a phone.

Voice reflects both, because it depends on the shape of the vocal tract and on speaking habits.

A biometric system typically works in four steps:

1. The system enrolls a person by capturing a sample and converting it into a template, a mathematical summary of the trait.
2. Later, it captures a new sample.
3. It compares the new sample with the stored template and produces a score.
4. It accepts or rejects the match based on a threshold.

Systems use biometrics in two modes:

• Verification (1:1) compares one sample with one claimed identity, as in a face match against an ID photo.
• Identification (1:N) compares one sample against many enrolled people, as in a face search.

Biometrics sit next to terms that are easy to mix up:

• Face match is a one-to-one comparison of two faces.
• Liveness detection confirms that the sample came from a live person.
• Biometric template is the stored mathematical summary, which is not the original image.