Apparatus and method for defending against unauthorized modification of programs

An apparatus for defending against an unauthorized modification of a program comprising:

• a storage;
• a first processor configured to execute at least one library function included in the program and to store at least one variable defined by the at least one library function or a value corresponding to the at least one variable stored in the storage;
• and
• a second processor configured to determine whether or not the program has been modified without authorization according to a determination on whether the variable or the value of the variable stored in the storage has been modified without authorization

A method for defending against an unauthorized modification of a program comprising:

• by a first processor, executing a program;
• by a second processor, acquiring a first value of a defined variable when a data definition part of the program is executed;
• by the second processor, comparing the first value with a second value used as a value of the variable when a data use part of the program is executed;
• and
• by the second processor, determining whether the program has been modified without authorization based on a result of the comparison.