Instruction generation apparatus for generating a computer program resistant to unauthorized analyses and tampering

An instruction generation apparatus which generates an output process instruction group including a plurality of instructions to be executed by a computer, said apparatus comprising:

• a memory;
• a branch-instruction generating unit configured to generate, as a part of the output process instruction group, a branch instruction which causes a processing route to branch to a first process instruction so that the computer executes the first process instruction, the first process instruction causing the computer to assign data to an assign-target variable;
• and
• a dependent-process-instruction generating unit configured to generate, as a part of the output process instruction group, a dependent process instruction dependent on the data assigned to the assign-target variable,
• the dependent process instruction causing the computer to execute a predetermined process in the output process instruction group onward when the data indicates predetermined contents, and
• the data assigned to the assign-target variable indicating a result of the first process instruction executed by the computer according to the branch instruction,
• wherein said dependent-process-instruction generating unit is configured to obtain a second process instruction which causes the computer to execute a predetermined process, and to generate the dependent process instruction by converting the second process instruction into the dependent process instruction, and
• the dependent process instruction causes the computer to derive an execution result identical to an execution result of the second process instruction when a value assigned to the assign-target variable equals a predetermined assumed value, the value assigned to the assign-target variable indicating an execution result of the first process instruction,
• said instruction generation apparatus further comprising:
• an assumed value calculating unit configured to calculate, as the assumed value, a value to be assigned to the assign-target variable in the first process instruction according to a predetermined condition,
• wherein said dependent-process-instruction generating unit is configured to generate the dependent process instruction which causes the computer to derive an execution result identical to the execution result of the second process instruction when the value assigned to the assign-target variable equals the assumed value calculated by said assumed value calculating unit, the value assigned to the assign-target variable indicating the execution result of the first process instruction.

An instruction generation apparatus which generates an output process instruction group including a plurality of instructions to be executed by a computer, said apparatus comprising:

• a memory;
• a branch-instruction generating unit configured to generate, as a part of the output process instruction group, a branch instruction which causes a processing route to branch to a first process instruction so that the computer executes the first process instruction, the first process instruction causing the computer to assign data to an assign-target variable;
• and
• a dependent-process-instruction generating unit configured to generate, as a part of the output process instruction group, a dependent process instruction dependent on the data assigned to the assign-target variable,
• the dependent process instruction causing the computer to execute a predetermined process in the output process instruction group onward when the data indicates predetermined contents, and
• the data assigned to the assign-target variable indicating a result of the first process instruction executed by the computer according to the branch instruction,
• wherein the dependent process instruction causes the computer to compare a value assigned to the assign-target variable and a predetermined assumed value, execute the predetermined process when the value assigned to the assign-target variable equals the predetermined assumed value, and suppress the execution of the predetermined process when the value assigned to the assign-target variable is different from the assumed value.

An instruction generation apparatus which generates an output process instruction group including a plurality of instructions to be executed by a computer, said apparatus comprising:

• a memory;
• a branch-instruction generating unit configured to generate, as a part of the output process instruction group, a branch instruction which causes a processing route to branch to a first process instruction so that the computer executes the first process instruction, the first process instruction causing the computer to assign data to an assign-target variable;
• and
• a dependent-process-instruction generating unit configured to generate, as a part of the output process instruction group, a dependent process instruction dependent on the data assigned to the assign-target variable,
• the dependent process instruction causing the computer to execute a predetermined process in the output process instruction group onward when the data indicates predetermined contents, and
• the data assigned to the assign-target variable indicating a result of the first process instruction executed by the computer according to the branch instruction,
• said instruction generation apparatus further comprising:
• an obtaining unit configured to obtain an input program which includes the first process instruction, a first preceding instruction serving as a branch source of the first process instruction, a first subsequent instruction serving as a branch destination of the first process instruction, a second process instruction serving as a branch destination of the first subsequent instruction, and a second subsequent instruction serving as a branch destination of the second process instruction;
• a conditional-branch-instruction generating unit configured to generate a conditional branch instruction;
• and
• an output unit configured to output an output program which includes the first process instruction, the first preceding instruction, the first subsequent instruction, and the second process instruction,
• wherein said dependent-process-instruction generating unit is configured to generate the dependent process instruction which causes the computer to derive an execution result identical to an execution result of the second subsequent instruction when the data assigned to the assign-target variable indicates predetermined contents,
• said branch-instruction generating unit is configured to generate the branch instruction which causes the processing route to branch from the second process instruction to the first process instruction so that the computer executes the first process instruction again after executing the second process instruction,
• said conditional-branch-instruction generating unit is configured to generate the conditional branch instruction which causes the processing route to branch from the first process instruction to the first subsequent instruction when the first condition is satisfied, and branch from the first process instruction to the dependent process instruction when the second condition is satisfied,
• said output unit is configured to output the output program which includes the dependent process instruction, the branch instruction, and the conditional branch instruction,
• the first condition is that the first preceding instruction has been executed immediately before the first process instruction when the computer executes the first process instruction, and
• the second condition is that the second process instruction has been executed immediately before the first process instruction when the computer executes the first process instruction.