The invention is directed to a method for a software provider to enable a software-acquiring entity to arrive from an existent first signed piece of code at a second signed piece of code. Both pieces of code were generated at the software provider by use of a first software archive generator under use of generation instructions. The software provider provides to the software-acquiring entity a difference code that comprises the steps necessary to arrive from the first signed piece of code at the second signed piece of code. The difference code is combinable at the software-acquiring entity with the first signed piece of code by a second software archive generator to generate the second signed piece of code. The second software archive generator is therefor to be fed with those generation instructions that were used by the first software archive generator for the generation of both pieces of code.