The present invention discloses a method and device for determining and outputting a similarity measure between two data strings each data string comprising data entities, comprising: receiving a first data string, receiving a second data string, which is characterized by determining consecutively following data entities in the first data string, determining the relative positions of the consecutively following data entities in the first data string, determining similar data entities with the same order in the second data string, determining the relative positions of the determined data entities in the second data string, determining a matching measure by determining how far the relative positions of data entities in the second data string match with the relative positions of consecutively following data entities in the first data string, and outputting a similarity measure which corresponds to the matching measure of at least one comparison result.