Patent ID: 8146168

Claim:
A program control apparatus for restricting activation of an expansion program that expands the functions of a basic program, said apparatus comprising: a specifying unit configured to specify a target program, which is to be activated, based upon identification information of a designated expansion program and constituent information of the basic program; a decryption unit configured to decrypt signature information, which is included in the target program and which has been obtained by encrypting the identification information of the expansion program and constituent information using a secret key, the signature information being decrypted using a public key that corresponds to the secret key; a checking unit configured to check the decrypted information, which has been decrypted by said decryption unit, against the identification information of the designated specified expansion program and the constituent information of the basic program; and a unit configured to enable, for expanding the basic program, execution of the target program, which has been specified by said specifying unit, if result of the check performed by said checking unit indicates a match, and to disable execution of the target program, which has been specified by said specifying unit, if result of the check performed by said checking unit indicates a non-match.