A mobile platform security apparatus and method is provided. The apparatus may perform a security setting by generating a first authentication key, a second authentication key, and a third authentication key for each function called by an application program. The apparatus may store the first authentication key and an identifier for identifying the application program in a first storage unit, the second authentication key and the identifier in a secret domain of a second storage unit, and register the third authentication key and the identifier as a function parameter in the application program. Subsequently, if the function is called by the application program, the apparatus may determine values for the first authentication key, the second authentication key, and the third authentication key corresponding to the called function, and may perform authentication processing using the three authentication key values.