| 摘要 |
PURPOSE:To completely protect stored contents from a third person by responding to the generation timing of a read strobe signal at the time of reading out data and working specified address data to form secret address data. CONSTITUTION:Random numbers are generated from random number generators 5, 13 by which a read strobe signal, the inverse of RD, is activated. In the 1st adder circuit 4, a selector 7 selects the subtracted result of a subtractor 6, and in the 2nd adder circuit 12, a selector 15 selects the computed result of an adder 14. Thereby, the specified address data are worked to form secret address data. The secret address data are transmitted to the 2nd adder circuit 12 through an address bus 17 and returned to the original specified address data in the 2nd adder circuit 12 and the read access of the memory 11 is executed to read out the data. Thus, the stored contents are prevented from being analyzed by the third person. |
