The handwritten signature in pen computing

The handwritten signature has many purposes and meanings; underlying these related purposes there are two ideas: the handwritten signature is a distinctive personal mark, because it is distinctive, its authenticity can be verified. Both these ideas can be called into question. A handwritten signature is distinctive and verifiable only if forgery is detectable and hence impracticable. It is illuminating to contrast what an electronically-captured signature might be with its paper equivalent. Needless to say, a paper signature is bulky to store and difficult to retrieve. Much of the visual verification which is currently done is cursory and depends on subjective criteria; it is totally impracticable to apply such techniques to large volumes of signatures. Finally, the data captured on paper are relatively few. By contrast, dynamic signature capture using a digitizer gives us stroke order, pen speed and acceleration as well as the image itself. This gives the opportunity to perform biometric tests to determine those characteristic aspects of an individual´s performance which are unique to him. The use of such data for verification purposes leaves a forger with more and bigger hurdles to surmount