| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a determining device for reducing a calculation cost when determining whether data is an element on a subgroup of a multiplicative group of a finite field. Ž<P>SOLUTION: The determining device is provided with: a first conversion section 102 converting first extension field representation data expressed in extension field representation into affine representation data expressed in affine representation; a second conversion section 103 converting the affine representation data into second extension field representation data expressed in extension field representation; and a determination section 104 which compares the first extension field representation data with the second extension field representation data and, when the first extension field representation data matches the second extension field representation data, and determines that the first extension field representation data is an element on a subgroup of a multiplicative group of a finite field. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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