APPARATUS, METHOD, AND COMPUTER PROGRAM PRODUCT FOR DECRYPTING, AND APPARATUS, METHOD, AND COMPUTER PROGRAM PRODUCT FOR ENCRYPTING

摘要

An input unit inputs encrypted data that elements of a subgroup and expressed in an affine representation. A transforming unit transforms the inputted encrypted data into projective representation data expressed in a projective representation. A plain data calculating unit subjects the projective representation data to a decrypting process previously defined by a cryptosystem, thereby calculating plain data expressed in the projective representation.