Evaluation of Brute-force Attack to Dynamic Signature Verification Using Synthetic Samples

A brute force attack using synthetically generated handwritten signatures is performed against a HMM-based signature recognition system. The generation algorithm of synthetic signatures is based on the spectral analysis of the trajectory functions and has proven to produce very realistic results. The experiments are carried out by attacking real signature models from the MCYT database (which comprises 8,250 signature samples from 330 users). Results show that such an attack is feasible, thus arising the necessity of introducing countermeasures against this type of vulnerability in real applications.