A delta file which encodes the difference between a first data file and a second data file is produced by determining a set of elemental data strings which are present in the two data files in a partial match in a graph being modeled. In the graph, each network node, representing data processing based on the first data file for producing a data byte of the second data file, is connected by network edges to all network nodes which are associated with a directly preceding data byte of the second data file. The network nodes and network edges are respectively assigned a cost value and a cost-optimized path in the graph is ascertained which, for all the day bytes of the second data file, contains only one network node per data byte. The cost-optimized path is taken as a basis for generating a delta file, containing a sequence of data processing operations and their data fields, which corresponds to the successive series of network nodes in the cost-optimized path.