1. A method for mapping a dynamic chirographic sample to a fixed metric vector space, the method comprising using at least one hardware processor for: providing a dynamic chirographic sample of a target subject, the dynamic chirographic sample of the target subject is a dynamic signature of the subject; providing a reference model for the dynamic chirographic sample, the reference model is a reference signature, the reference signature is an estimated Universal-Background-Signature (UBS), wherein the estimated UBS is estimated by: providing a development set comprising a plurality of dynamic chirographic samples of a plurality of subjects; setting the UBS to a predefined time length; linearly segmenting the plurality of dynamic chirographic samples of the development set to achieve the predefined time length; estimating an initial UBS based on the linearly segmented plurality of dynamic chirographic samples; and iteratively refining the UBS by utilizing an Expectation-Maximization (EM) algorithm; aligning the dynamic chirographic sample of the target subject to the reference model; and generating a chirographic supervector based on the aligned dynamic chirographic sample of the target subject, wherein the supervector represents features of the dynamic chirographic sample of the target subject mapped in a fixed metric vector space.