On-line handwritten data verification, such as a signature, is obtained based on the comparison of the dynamics of a sample and a reference signatures by use of a new implementation of correlation function analysis. The dynamic data concerning scriber movement during the process of signature making is recorded and converted to digital form. Prior to correlation function analysis for evaluating a to-be-verified signature, reference signature dynamic data and to-be-verified signature dynamic data digital signals are pre-processed to eliminate time distortions. The compared signals are reduced to the same time scale, thereby providing a frequency coincidence between the signals. In order to eliminate the phase distortions, a "sliding window" mechanism is used to establish the mapping between phase coincident regions of the reference and of the to-be-verified signals. Then the multi-dimensional cross-correlation function analysis is applied to the pair of indivisible stationary signals. The sliding window mechanism provides two additional criteria to distinguish between authentic and forged signatures by determination of different characteristics of time distortions for such signals. The resulting measures of similarity are then compared with thresholds that have been selected to determine acceptance or rejection of the signature. The method and the apparatus can be applied for signature authentication in a wide variety of applications like security of physical access, computer network access, facsimile legalization, credit card industry, and many others.