Information Technology Reference
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the iris scan and the shape of the face. The most used behavioural features are
the analysis of the signature and the speech recognition.
In literature there are various other techniques including body pace
examination, scanning the palm, the geometry of the veins of the hand, DNA
analysis, body odour and keystroke dynamics on the keyboard.
The process to use a biometric system for security purposes essentially
consists of two phases. In a first phase of registration (or enrolment) the
biometric characteristic is captured and a biometric template is extracted
according to a specific algorithm suitable for the feature.
The template is a mathematical representation of biometric data and is
different from individual to individual.
A template can vary the size depending on the amount of information that
it contains (to preserve the geometry of a hand a few bytes, for facial
recognition will go to several thousand bytes). The template is subsequently
stored in an area of memory. This may be a local structure (the point at which
the particular user), a central memory (so it comes to biometric template
database) or a memory contained within a smart card owned by the user.
The second phase is the actual identification process. A scan of the
biometric feature is performed. This scanning is processed using the same
algorithms used in the previous phase of registration and the biometric
template is extracted. This template is then compared with those ones stored
in the database of the registered users.
In this last step a value of similarity found between the two templates (the
one that [13] defines as matching score) is computed. This step allows
evaluating and modifying the error sensitivity with which the biometric
system works.
The identification process can be optionally followed by a phase of
adaptation: the system, having recognized the user, updates its biometric
template in the database with what has just been calculated in the identifica-
tion. This is a way to manage the problem of change in time of the biometric
feature that is updated at every positive identification of the user.
5.3.2 Hardware keys
A hardware key is just a digital identity card, which must be kept safe. It is an
object with memory in it, whose capacity varies from model to model. In this
memory, data such as passwords, digital signatures, codes and so on can be
written. The hardware security key is mostly based on the reliability of the
key holder, as a matter of fact if someone has personal identification data
stored on a key and leaves it unattended, then security can be easily
compromised.
Apart from that, the degree of security of a hardware key is undoubtedly
better to classical password text. However it is possible to 'tamper with'
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