| 摘要 |
PROBLEM TO BE SOLVED: To eliminate limitation of a class of a public key to be generated, and to block a decoding method based on the limited class when a private key is composed of two sections. SOLUTION: When a fibration X(x, y, t) which is a part of a public key is generated, the limitation of the class of the public key to be generated is eliminated by employing a configuration wherein a term of c<SB>ij</SB>x<SP>i</SP>y<SP>j</SP>is included in the form of the fibration X(x, y, t). Here, in order to realize the configuration wherein the term of c<SB>ij</SB>x<SP>i</SP>y<SP>j</SP>is included, the term of c<SB>ij</SB>x<SP>i</SP>y<SP>j</SP>is defined as the term other than a first-order term or a constant term c<SB>00</SB>. First, the term of c<SB>ij</SB>x<SP>i</SP>y<SP>j</SP>is randomly generated. Then, based on the term of c<SB>ij</SB>x<SP>i</SP>y<SP>j</SP>and a one-variable polynomial in two sections D<SB>1</SB>and D<SB>2</SB>, the coefficient of the first-order term is generated. Lastly, based on the term of c<SB>ij</SB>x<SP>i</SP>y<SP>j</SP>and the first-order term, the constant term c<SB>00</SB>is generated. COPYRIGHT: (C)2008,JPO&INPIT |
