Identification of biometric features
In order to be able to use methods for person identification, various prerequisites have to be fulfilled: The features may only occur in one person (uniqueness), should occur in as many people as possible (universality), do not change or change only slightly over a period of time (constancy), if possible technically simple (measurability), convenient and fast for the user (user friendliness) as well as practicable, as cost-effective as possible and with little error-prone detection. In order to optimize these aspects, several methods with different advantages and disadvantages can be combined.
An increased security by means of biometric procedures, however, comes at the expense of comfort, which is accepted in normal everyday life only within certain limits. This too is not new knowledge - in 1885 in Cincinnati the proposal to protect train tickets from abuse by means of a thumbprint was dropped, since one did not want to expect this from the travelers.
Possibilities of identification
The idea of using individual recognition features is not entirely new.
- The personal handwriting has long been used as a signature, since recently also as a digital signature; the risk of counterfeiting has always been relatively large.
- Dactyloscopy, the process of using fingerprints for identification, has been firmly established in the fight against crime for about 100 years. In China, fingerprints were used to certify treaties as early as about the 8th century AD, while in other cultures archaeologists found stone drawings, clay tablets and vases with even older fingerprints. Fingerprints have low false detection rates.
- Not only the grooves of the fingertips, but also the hand geometry and lines as well as the venous pattern of the back of the hand are used as biometric features (the latter, for example, since 2005 in the German Federal Ministry for Foreign Affairs). So far, the quality of detection is unclear, especially in the case of changes due to work and aging processes. Another disadvantage is that the hand geometry has a lot of similarities in different individuals.
- A measurement of the face (for example, for season ticket holders in the Zoo Hannover) or the rainbow or retina (Iriscan, Retinascan, for example, frequent flyers at Frankfurt airport) are other options that are already used. Eye feature definitions are considered very safe, but are also very costly and are - due to the laser beam used for scanning - accepted only conditionally.
- Photographs in ID cards can be compared with today's technology automatically with the face of the person concerned ("machine-readable ID cards"). However, in practice, not enough samples have been investigated so far in order to be able to make a reliable statement about the relationship between image quality and recognition probability.
- In the case of a genetic fingerprint, the DNA of a person is compared with a database maintained by the Federal Criminal Police Office (DNA analysis) and serves as identification in criminal proceedings.
In principle, further biometric features are conceivable as a suitable recognition feature, but are not yet used. Examples are voice and speech rhythm, body movements, typing behavior on keyboards and body odor.