Verification system, verification method, and recording medium
A verification system includes: a first verification device that verifies integrity of a first verification target; and a second verification device that has a higher security privilege than the first verification device and verifies integrity of the first verification device. The first verification device includes: a first verifier that refers to first verification related information including first verification target information and a first expected value, generates a first verification value by performing the predetermined operation on data on a first storage area storing the first program, and verifies integrity by comparing the first verification value with the first expected value; and a first updater that accepts a first update request for updating the first verification related information when receiving the first update request from the second verification device or when receiving the first update request while the first verification related information is updated, and updates the first verification related information.
1 . A verification system comprising:
a first verification device that verifies integrity of a first verification target; and
a second verification device that has a higher security privilege than the first verification device and verifies integrity of the first verification device, wherein
the first verification device includes:
a first memory; and
a first processor coupled to the first memory, and
the first processor, by using the first memory, operates as:
a first verifier that refers to first verification related information including first verification target information and a first expected value, the first verification target information indicating the first verification target, the first expected value being generated by performing a predetermined operation on first data on a first program implementing the first verification target, generates a first verification value by performing the predetermined operation on data on a first storage area storing the first program implementing the first verification target indicated by the first verification target information, and verifies the integrity of the first verification target by comparing the first verification value with the first expected value; and
a first updater that accepts, when the first program is updated, a first update request for updating the first verification related information when receiving the first update request from the second verification device or when receiving the first update request while the first verification related information is updated, and that updates the first verification related information based on the accepted first update request.
2 . The verification system according to claim 1 , further comprising
the first verification target, wherein
the first verification target is a third verification device, the third verification device verifying integrity of a second verification target different from the first verification target and having a lower security privilege than the first verification device,
the third verification device includes:
a second memory; and
a second processor coupled to the second memory, and
the second processor, by using the second memory, operates as:
a second verifier that refers to second verification related information including second verification n target information and a second expected value, the second verification target information indicating the second verification target, the second expected value being generated by performing the predetermined operation on second data on a second program implementing the second verification target, generates a second verification value by performing the predetermined operation on data on a second storage area storing the second program implementing second verification target indicated by the second verification target information, and verifies the integrity of the second verification target by comparing the second verification value with the second expected value; and
a second updater that updates, when receiving a second update request for updating the second verification related information from the first verification device, the second verification related information based on the received second update request, and
during a predetermined period in updating of the first verification related information, the first verification device transmits the second update request to the third verification device.
3 . The verification system according to claim 2 , wherein
the third verification device transmits completion information to the first verification device after updating of the second verification related information is completed, the completion information indicating completion of the updating of the second verification related information, and
when the second verification related information is updated, the first verification device does not update the first verification related information but transmits the second update request to the third verification device and, after receiving the completion information from the third verification device, updates the first verification related information.
4 . The verification system according to claim 3 , wherein
when the first storage area is changed as a result of the updating of the second verification related information, the third verification device transmits first area information indicating the changed first storage area to the first verification device, and
the first verification device updates the first verification target information based on the first area information.
5 . The verification system according to claim 1 , wherein when a third storage area that stores a third program implementing the first verification device is changed as a result of the updating of the first verification related information, the first verification device transmits third area information indicating the changed third storage area to the second verification device.
6 . The verification system according to claim 1 , wherein
the verification system includes a plurality of verification devices including the first verification device and the second verification device,
each verification device of the plurality of verification devices verifies integrity of another verification device that has a lower security privilege than the verification device,
out of the plurality of verification devices, a highest-level verification device having a highest security privilege is implemented in a secure area, and
one or more low-level verification devices that are the plurality of verification devices other than the highest-level verification device is implemented in a normal area.
7 . The verification system according to claim 1 , wherein
updating of the first program is any one of deleting the first program, modifying the first program, or adding another program, and
after the updating of the first program is completed and after updating of the first verification related information is completed, the first verification device executes the updated first program.
8 . A verification method by a verification system that includes a first verification device and a second verification device, the first verification device verifying integrity of a first verification target, the second verification device having a higher security privilege than the first verification device and verifying integrity of the first verification device, wherein
the first verification device:
refers to first verification related information including first verification target information and a first expected value, the first verification target information indicating the first verification target, the first expected value being generated by performing a predetermined operation on first data on a first program implementing the first verification target, generates a first verification value by performing the predetermined operation on data on a first storage area storing the first program implementing the first verification target indicated by the first verification target information, and verifies the integrity of the first verification target by comparing the first verification value with the first expected value; and
accepts, when the first program is updated, a first update request for updating the first verification related information when receiving the first update request from the second verification device or when receiving the first update request while the first verification related information is updated, and updates the first verification related information based on the accepted first update request.
9 . A non-transitory computer-readable recording medium storing a program for causing a computer to execute the verification method according to claim 8 .