Generating a data object identifier by dividing the data in the data object into a plurality of chunks; processing each chunk using a clustering algorithm to generate, for each chunk, a pair of values characterizing the data in the chunk, thereby giving rise to a plurality of pairs of values (PoV); generating a plurality of nodes in a two dimensional space each corresponding to a respective PoV, wherein, for any given PoV, the values in the given PoV are indicative of location coordinates of the corresponding node in the two dimensional space; generating a plurality of features related to the plurality of nodes, each feature characterizing a spatial relationship between three or more nodes; and generating the data object identifier by arranging the features in a feature vector in accordance with predetermined rules.