Patent ID: 8079078

Claim:
An authentication apparatus configured to authenticate access from an external apparatus by generating encryption data on the basis of specified identification data, said authentication apparatus comprising: means for receiving first identification data and second identification data different from said first identification data from the external apparatus; first selection means for selecting an encryption method from among a plurality of different encryption methods on the basis of said first identification data; second selection means for selecting plaintext data to be encrypted from among a plurality of different pieces of plaintext data on the basis of said second identification data; encryption means for obtaining encryption data having said plaintext data selected by said second selection means encrypted by said encryption method selected by said first selection means, and said encryption means includes correspondence table data indicating different combinations of at least one of said plurality of different encryption methods and said plurality of different pieces of plaintext data and said encryption data corresponding to each combination, obtains said encryption data from a particular combination included in the correspondence table data corresponding to selection results by said first selection means and said second selection means, and when it is determined that encryption data of said combination corresponding to the selection results by said first selection means and said second selection means does not exist within said correspondence table data, said encryption means generates said encryption data by performing said encryption based on the selection results of said first selection means and said second selection means without utilizing the correspondence table data; and authentication means for authenticating the access from the external apparatus based on said encryption data.