1. A computer-implemented method of determining representative values for data, wherein said computer-implemented method comprises: (a) determining a first one-way mapping value for a first portion of said data as a first representative value of said first portion of said data, wherein said first one-way mapping value is not intended to map back to said first portion of said data; and (b) determining a second one-way mapping value for a second portion of said data as a second representative value of said second portion of said data, wherein said second one-way mapping value is not intended to map back to said second portion of said data, and wherein said determining (b) determines said second one-way mapping value independently from said first portion of said data and independently from said determining (a) of said first one-way mapping value, thereby determining two independent one-way mapping values based on said data.