a quantised biometric method comprising the steps of : acquiring a value of a biometric measurement variable from a registrant to generate an acquired registrant variable ; identifying a container from a preconfigured number of containers each of preconfigured , substantially non - overlapping , upper and lower boundary values , whose boundary values substantially embrace the value of the acquired registrant variable , to generate a registrant container ; adapting the upper and lower boundary values of the registrant container so that the acquired registrant variable is centred therein ; adapting the upper and lower boundary values of the remaining containers so that they remain substantially non - overlapping with each other and those of the registrant container , to generate a plurality of registrant imposter containers ; storing the boundary values of the registrant container and the registrant imposter containers and an acquired identity of the registrant ; acquiring a value of the biometric measurement variable from a user to generate an acquired user variable ; acquiring from the user a claim to an identity to generate a claimed identity ; retrieving the containers of the registrant with the claimed identity to generate the claimed registrant container and claimed registrant imposter containers ; deciding that the user has passed the quantised biometric method in the event the boundary values of the claimed registrant container substantially embrace the acquired user variable .