Abstract: A method for compressing an interpreted object code in a system using an interpreter, by identifying, in the interpreted object-coded program, similar non-contiguous groups of instructions, of arbitrarily complex structure, by replacing all or part of said groups in the interpreted object code of the program with newly-created specialized instructions and by instrumenting the interpreter and/or the interpreted object code of the program so as to render it capable of implementing the newly-created instructions.

Abstract: The invention concerns a method for compressing program code for execution in a system with few physical resources. This method comprises a semantic analysis of the code as to identify the objects accessed at each program point and to replace in this program groups of instructions used to access the objects by more compact specialised instructions.

Abstract: The product/program and the process according to the invention make it possible to insert into an item of software in source code, in particular Java, watermarks which comply with the semantics of the program and are very difficult to detect. They make it possible to: compute a secret semantic signature of a software or hardware computer program from an infinity of possible secret semantic signatures; —mark a software or hardware computer program by inserting a visible or invisible watermark making it possible to retrieve an authenticator of the original program; retrieve the mark and extract this authenticator from the secret semantic signature of the watermarked software or hardware computer program. The secret semantic signature of the software or hardware computer program to be protected is characteristic of the semantics of said program.

Abstract: The invention concerns a method useful for compressing intermediate object-coded programmes executable in an onboard system with few physical resources. It comprises using a semantic information to modify the intermediate object code of the programme and eliminating instructions of the intermediate object code of the programme which are no longer required as a result of said modification.