| 摘要 |
<p>PURPOSE:To improve safety while preventing the function of a built-in integrated circuit from being optically analyzed by composing the highest layer of the integrated circuit having multilayered structure of elements to which the analysis is permitted. CONSTITUTION:The integrated circuit to a CPU 11, special arithmetic circuit 12, RAM 13, mask ROM 14 and EEPROM 15 is composed of the LSI of one chip laminating them in the multiplayered structure. ON the highest layer, the integrated circuit of the EEPROM 15 is arranged to prevent stored contents from being judged even when it is analyzed. Therefore, a control program, password and code key or the like stored in he special arithmetic circuit 12, mask ROM 14 and EEPROM 15 after the second layer can not be optically analyzed. Thus, even when an IC card 1 is decomposed and analyzed, the built-in function can not be analyzed and the safety can be improved.</p> |
