Image forming apparatus and job request control method instructed by authenticated users

An image forming apparatus for executing a job request based on authority of an account, comprising:

• a certification ticket generation unit configured to generate a certification ticket corresponding to the job request and account information of the account instructing execution of the job request;
• a job request information generation unit configured to generate job request information of the job request;
• a certification ticket validity determination unit configured to determine whether the certification ticket is valid;
• a job request validity determination unit configured to determine whether the account has the authority to execute the job request by referring to authority information stored in a nonvolatile storage unit of the image forming apparatus based on acquired job request information corresponding to the certification ticket and the account information corresponding to the certification ticket;
• a job request control unit configured to execute the job request, the execution of the job request having been determined valid by the job request validity determination unit;
• a job request management unit that, when an instruction to execute the job request includes a prescribed execution start time to start execution of the job request, is configured to acquire the certification ticket from the storage unit at a prescribed time ahead of the prescribed execution start time determined based on the prescribed execution start time and a time to perform an acquisition of the certification ticket from the storage unit and to request to determine a validity of the certification ticket;
• and
• an encryption unit configured to select for encryption of the certification ticket one of plural encryption methods based on the prescribed execution start time to start execution of the job request.