User authentication system and portable terminal

1. A user authentication system comprising: a main body device; and an authentication device that communicates with the main body device, the user authentication system authenticating a user of the main body device,

wherein the main body device comprises:

an authentication code transmission requesting unit that generates an authentication code transmission request including a first value selected for each instance of transmission, and transmits the authentication code transmission request to the authentication device;

a verification unit that decides that the authentication is successful if an authentication code transmitted from the authentication device in response to the authentication code transmission request is included in a verification authentication code generated in response to the first value; and

an unlocking unit that enables a predetermined functionality if the verification unit decides that the authentication is successful;

a main body position information acquiring unit that acquires position information of the main body device at predetermined time intervals; and

a main body storage unit that stores the acquired position information of the main body device in association with acquisition times,

wherein the authentication device comprises:

an authentication code reply unit that generates the authentication code in response to the first value included in the authentication code transmission request, and transmits the authentication code to the main body device;

an authentication position information acquiring unit that acquires position information of the authentication device at predetermined time intervals; and

an authentication storage unit that stores the acquired position information of the authentication device in association with acquisition times,

wherein the authentication code transmission requesting unit uses, as the first value, a predetermined past period during which the main body position information acquiring unit has acquired the position information of the main body device,

wherein the verification unit uses, as the verification authentication code, the position information of the main body device stored in the main body storage unit in association with the predetermined past period, and

wherein the authentication code reply unit uses, as the authentication code, the position information of the authentication device stored in the authentication storage unit in association with the predetermined past period included in the authentication code transmission request.

2. The user authentication system according to claim 1 , wherein the predetermined functionality is a settlement functionality.

3. The user authentication system according to claim 1 ,

wherein the main body device further comprises:

a first authentication unit that executes first authentication different from authentication by using the authentication device; and

a receiving unit that receives an operation instruction,

wherein the unlocking unit further makes it possible to accept the operation instruction via the receiving unit if the authentication by the first authentication unit is successful, and

wherein the authentication code transmission requesting unit generates the authentication code transmission request if the operation instruction for execution of the functionality is received via the receiving unit.

4. The user authentication system according to claim 1 ,

wherein the main body device further comprises a second authentication unit that executes second authentication different from authentication by using the authentication device, and

wherein the second authentication unit executes the second authentication if the verification unit does not decide that the authentication is successful.

5. The user authentication system according to claim 1 ,

wherein the main body device further comprises:

a transmitting/receiving unit that establishes the communication with the authentication device; and

a main body storage unit that accumulates non-establishment periods which are periods during which the transmitting/receiving unit has not been able to establish the communication, and

wherein the authentication code transmission requesting unit does not generate the authentication code transmission request if the accumulated non-establishment periods exceed a predetermined period.

6. A user authentication method to be performed in a user authentication system, the user authentication system comprising: a main body device; and an authentication device that communicates with the main body device, the user authentication system authenticating a user of the main body device, the method comprising:

in the main body device,

generating an authentication code transmission request including a first value selected for each instance of transmission, and transmitting the authentication code transmission request to the authentication device;

deciding that the authentication is successful if an authentication code transmitted from the authentication device in response to the authentication code transmission request is included in a verification authentication code generated in response to the first value; and

enabling a predetermined functionality if it is decided that the authentication is successful;

acquiring position information of the main body device at predetermined time intervals; and

storing the acquired position information of the main body device in association with acquisition times; and

in the authentication device,

generating the authentication code in response to the first value included in the authentication code transmission request, and transmitting the authentication code to the main body device;

acquiring position information of the authentication device at predetermined time intervals; and

storing the acquired position information of the authentication device in association with acquisition times,

wherein a predetermined past period during which the position information of the main body device has been acquired is used as the first value,

wherein the position information of the main body device stored in the main body device in association with the predetermined past period is used as the verification authentication code, and

wherein the position information of the authentication device stored in the authentication device in association with the predetermined past period included in the authentication code transmission request is used as the authentication code.

7. The user authentication method according to claim 6 , wherein the predetermined functionality is a settlement functionality.

8. The user authentication method according to claim 6 , further comprising:

in the main body device,

executing first authentication different from authentication using the authentication device; and

receiving an operation instruction,

wherein, in the main body device, the enabling the predetermined functionality further makes it possible to accept the operation instruction if the first authentication is successful, and

wherein, in the main body device, the generating an authentication code transmission request generates the authentication code transmission request if the operation instruction for execution of the functionality is received.

9. The user authentication method according to claim 6 , further comprising, in the main body device, executing second authentication different from authentication using the authentication device,

wherein the second authentication executes the second authentication if it is not determined that the authentication is not successful.

10. The user authentication method according to claim 6 , further comprising:

in the main body device,

establishing the communication with the authentication device; and

accumulating non-establishment periods which are periods during which the communication has not been established, and

wherein, in the main body device, the authentication code transmission request is not generated if the accumulated non-establishment periods exceed a predetermined period.