| 摘要 |
PROBLEM TO BE SOLVED: To prevent leakage of a randomized polynomial in a public key cryptography using an algebraic curved surface. SOLUTION: In an encryption device 10, two multiplication results X(x, y, t)r(x, y, t) and f(t)s(x, y, t) included in a ciphertext F are constituted of like terms of a variable x<SP>i</SP>y<SP>j</SP>(i, j are of the degrees≥0) seen as the polynomial of x and y. Thus, even when a method of analyzing the term that exists in one multiplication result X(x, y, t)r(x, y, t) but does not exist in the other multiplication result f(t)s(x, y, t), each term can not be discriminated and the leakage of a part of r(x, y, t) is prevented. COPYRIGHT: (C)2008,JPO&INPIT |
