Strategies for exploiting signature verification based on complexity estimates

Biometrics is a diverse and increasingly important field, covering many modalities and types of individual characteristics. The biometric modality with perhaps the longest history, and one which certainly enjoys the widest degree of public acceptance, is the handwritten signature [1]. However, checking and analysing handwritten signatures as a means of establishing or verifying identity is both a challenge for technology (i.e. algorithms for robust automatic signature verification are constantly sought) and for the powers of human perception, since there are many situations where signature checking by machine might be inappropriate or, at least at present, insufficiently reliable, for routine use. This is especially the case when the risk of forgery is high, or where acceptance of a nonauthentic signature could have serious consequences. Furthermore, it can reasonably be claimed that a better understanding of human ability in analysing and authenticating signatures can lead indirectly to the specification of more accurate and perhaps more robust techniques which can be implemented automatically.