User's Guide

30
About the Security Level
The security level is an important part of the identification system. A higher security level
reduces the risk of an unauthorised person logging into an account. An administrator can
set the security level for biometric users. The security level is set globally; i.e. the set secu-
rity level affects all biometric users in the domain.
The False Acceptance Rate, FAR, is a parameter used to indicate the probability that an
unauthorised user is given access to an account. The False Rejection Rate, FRR, indicates
the probability that an authorised user is denied access to an account.
A secure system, i.e. a system with a high security level, means a low false
acceptance rate.
• Higher security levels = an excellent match between the fingerprint on the
sensor and the fingerprint template in the database is required. The FAR is
very low; the FRR is comparatively high.
• Lower security levels = a less perfect match between the fingerprint on the
sensor and the equivalent fingerprint template in the database is required.
The FAR is comparatively high; the FRR is low.
Higher security levels (level 6 or 7) result in:
• A very secure system. It will be virtually impossible for an unauthorised
person to log into a user account.
• A system, which sometimes rejects an authorised user trying to log into an
account. A small scratch, a distorted fingerprint or poor finger positioning
on the fingerprint reader may produce a fingerprint that the system does not
accept as a satisfactory match to the fingerprint template stored in the database.
Lower security levels (level 1or 2) result in:
• A less secure system. At lower security levels, the risk of an unauthorised
user logging into an account increases.
• A system, which very rarely rejects an authorised user who wants to log into
an account.
Chapter 4 The BioManager