| 摘要 |
<p>A method and an apparatus capable of realizing at a high speed an elliptic curve cryptography in a finite field of characteristic 2, in which the elliptic curve is given by y<2> + xy = x<3> + ax<2> + b (b NOTEQUAL 0) and an elliptic curve cryptography method which can protect private key information against leaking from deviation information of processing time to thereby defend a cipher text against a timing attack and a differential power analysis (DPA) attack are provided. To this end, an arithmetic process for executing scalar multiplication arithmetic d(x, y) a constant number of times per bit of the private key d is adopted. Further, for the scalar multiplication d(x, y), a random number k is generated upon transformation of the affine coordinates (x, y) to the projective coordinates for thereby effectuating the transformation (x, y) -> Äkx, ky, kÜ or alternatively (x, y) -> Äk<2>x, k<3>y, kÜ. Thus, object for the arithmetic is varied by the random number (k). <IMAGE></p> |
