Patent ID: 8127368

Claim:
A semiconductor memory card for use with an electronic device, said semiconductor memory card comprising: a rewritable nonvolatile memory having an authentication area and a non-authentication area; and a control unit operable to control accesses by the electronic device to the authentication area and the non-authentication area in said rewritable nonvolatile memory; said control unit comprising: an authentication unit operable to perform an authentication process to check whether the electronic device has authority to access said semiconductor memory card, and affirmatively authenticate the electronic device when the electronic device has authority to access said semiconductor memory card; an authentication area access control unit operable to permit the electronic device to access the authentication area when said authentication unit affirmatively authenticates the electronic device; a device operable to hold information relating to an area size of said rewritable nonvolatile memory; and an area resizing unit operable to resize the authentication area and the non-authentication area, wherein the authentication area and the non-authentication area are provided by dividing a continuous area of a predetermined size in said rewritable nonvolatile memory into two parts, the authentication area is accessible by the electronic device only when the electronic device is authenticated, and the non-authentication area is accessible by the electronic device regardless of whether or not the electronic device is authenticated, the authentication area stores an encryption key therein, and the non-authentication area stores encrypted data and general data that is not encrypted therein, the encrypted data to be decrypted by using the encryption key, and said area resizing unit is operable to receive an instruction sent from the electronic device that includes information relating to the area size of said rewritable nonvolatile memory when said authentication unit affirmatively authenticates the electronic device, and is operable to resize the authentication area and the non-authentication area based on the received information relating to the area size of said rewritable nonvolatile memory.