Unique or nearly-unique characteristics of the individual
(something you are) is used to authenticate identity. Examples include
finger prints, voice prints, retinal blood vessel patterns, DNA sequences,
and facial characteristics.
Complexity: While the overall field of
biometric identification and authentication is quite complex, these methods
are normally used to authenticate identity or differentiate between
identities from relatively small populations (typically a few thousand
individuals), and this process is feasible with fairly common data
correlation techniques.
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