A system (600) for facilitating tracing copies (634) of an implementation of a computational method (602). A network generator (604) for generating a network of look-up tables representing steps of the computational method (602), the network being formed by using an output value of a first look-up table as an input value of a different second look-up table. A personalizer (606) for generating a plurality of different versions of the network of look-up tables by changing at least one value in the network of look-up tables, end results of the version corresponding to a relevant domain of input values being substantially the same for each version. An associator (608) for associating individual versions with individual stations (610) or users (632) of stations (610). The computational method (602) includes a 10 cryptographic scheme and a cryptographic key.