Patent ID: 8176106

Claim:
A method of using a physical token, which provides measurable parameters, to derive at least one data set, the method comprising the steps of: measuring a plurality of values of at least one of said parameters provided by the physical token; calculating, from the measured values, a measure of variance; storing information which enables determination of quantization intervals; determining, based on said measure of variance, quantization intervals into which a measured value is to be quantized, each quantization interval being associated with a possible value of a data set; and measuring a value of said at least one parameter and quantizing the measured value into a determined quantization interval, wherein a data set is derived from a value associated with the quantization interval into which the measured value is quantized; wherein a plurality of measurements are made for at least one selected parameter and an intraclass variance is calculated from the measured values of the respective at least one selected parameter.