Abstract: An obfuscation device includes a first instruction generating unit, for each of a first process and a second process, which generates an initialization instruction for securing a management area for managing identification information indicating an instruction block that should be executed next so as to proceed with the process. Further, a second instruction generating unit generates a selection instruction (i) to make a first selection selecting a process that should be proceeded out of the first process and the second process, (ii) to make a second selection selecting an instruction block indicated by the identification information managed in the management area as an instruction block that should be executed for proceeding with the process selected by the first selection, and (iii) to cause the execution device to execute the instruction block selected by the second selection, and stores the selection instruction in a storage unit.

Abstract: To provide a program conversion device capable of executing a program that includes a secret operation using secret information without exposure of the secret information in a memory. In an execution program generation device, with respect to an original program that includes the secret operation, a combining function generation unit generates combining function processing for applying a bitwise self-dual function to an input value, a split secret information generation unit generates pieces of split secret information by performing an inverse operation of the self-dual function, a program conversion unit generates pieces of split secret operation processing each for performing the operation between each bit value of the operand information and a corresponding bit value of a different piece of the split secret information, and replaces the secret operation processing with the pieces of the split secret operation processing and the combining function processing.

Abstract: It is an object of the present invention to provide an obfuscation device that can achieve both sufficient obfuscation and the appropriate instruction block to be executed. In the obfuscation device, a first instruction generating unit, for each of the first process and the second process, generates an initialization instruction for securing a management area for managing the identification information indicating an instruction block that should be executed next so as to proceed with the process, and to store the initialization instruction in said storage unit.

Abstract: A method invocation modification unit modifies method invocation described in a body program to dynamic invocation and modifies the method invocation to invocation via an execution support device. An encryption unit modifies the body program by encrypting a character string designating the dynamic invocation after modification by the method invocation modification unit. Therefore, the method invocation can be hidden and understanding of the program can be made difficult.

Abstract: To provide a program conversion device capable of executing a program that includes a secret operation for decrypting encrypted data using secret information without exposure of the secret information in a memory thereby to improve confidentiality in execution of the program.