The history of biometry
The mechanical key is probably the oldest proof of identity and authorization based on technical equipment and not on individual recognition of a person. In this case the proof of identity and authorization is based on possession. More recent forms of the same category are all types of plastic cards which can be read electrically, magnetically or optically.

Today all these forms of authorization have reached a high technical standard and are to a certain extent hard to imitate or forge. Nevertheless they all have one principal disadvantage: the technical device can determine the identity and the authorization of the card or key but not of the owner or bearer. In other words: property can be stolen, get lost or passed on to unauthorized persons.

To avoid this disadvantage other systems do not rely on possession but on knowledge. Passwords are one of the oldest ways to prove identity or privileges. In recent times this procedure has also been automated by using codewords or personal identification numbers (PIN). The abuse through theft is thus impossible but not the passing on of information to unauthorized persons.

The security provided by PINs is practically eliminated if PINs are e.g. written on credit cards, which many people still do despite warnings.

The combination of possession-based and knowledge-based systems reduces the risk of fraud even more but do not exclude the principal deficiency that the bearer can still not be definitively identified.

The only means to ascertain the identity of a person irrefutably is to recognize a personĀ“s characteristics. These characteristics are called biometric and the technique of recognition biometry.

There are many different biometric characteristics of a person. Should the measurement and comparison with previously stored data proceed automatically then the biometric characteristics have to meet the following requirements:
  • Invariable characteristics The characteristics should not change over a longer period of time.
  • Measurability The characteristics should include unique features to be able to distinguish one person from any other.
  • Acceptance The measurement of the characteristics has to be acceptable for a wide range of users. Invasive techniques are to be excluded, i.e. techniques that need part of the body or (apparently) affect it.
  • Reducability It must be possible to reduce the measured data to an easily manageable data file.
  • Reliability The method has to have a high degree of reliability and reproducibility.
  • Data privacy The privacy of the registered person has to be guaranteed.

With these requirements in mind only a few characteristics remain that can be automatically measured and which have been examined in the past.
  • Geometry of the hand
  • Handwriting
  • Retina of the eye
  • Iris of the eye
  • Voice
  • Face
  • Fingerprint


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