| 摘要 |
In an embodiment, regarding an addition of a kb-bit number A and a b-bit random number r, element data of a pre-calculated table C′ is set based on a sum AH+rH of a value AH of upper b/2 bits of a number A2, which is lower b bits of the number A, and a value rH of upper b/2 bits of the random number r and the sum AL+rL of a value AL of lower b/2 bits of the number A2 and a value rL of lower b/2 bits of the random number r in such a way that presence/absence of carrying-over of A2+r is indicated. Accordingly, the size of the pre-calculated table needed to be reduced for obtaining an addition result of upper (k−1)b bits by mutually adding the kb-bit number A and the b-bit number r. |
