A data provision system comprising: a data provision device; and an in-vehicle computer installed in a vehicle, wherein the data provision device includes a vehicle interface configured to transmit data to and receive data from the vehicle, the data provision device is configured to transmit first data, which is a computer program or setting data, to be applied to the in-vehicle computer and a first expected value of the first data to the vehicle through the vehicle interface, wherein the first expected value is calculated by the data provision device using a key shared between the data provision device and the in-vehicle computer in advance; the in-vehicle computer includes: a first interface unit configured to transmit data to and receive data from a device outside the in-vehicle computer; a control unit configured to apply the first data provided by the data provision device to the in-vehicle computer, set the first expected value, which is provided by the data provision device as a second expected value for use in a secure boot, and execute the secure boot after applying the first data to the in-vehicle computer; and a measurement unit configured to, in the secure boot, calculate a measurement value of the first data applied to the in-vehicle computer using said shared key and verify the measurement value on the basis of the second expected value, wherein the control unit is configured to transmit, through the first interface unit, a data application result indicating success or failure of application of the first data to the in-vehicle computer based on a result of the verification by the measurement unit, wherein the secure boot further comprises: advancing the execution of the first data if the data application result indicating success and stopping the execution of the the first data if the data application result indicating failure; the data provision device is configured to receive the data application result from the vehicle through the vehicle interface. a data provision device; and an in-vehicle computer installed in a vehicle, wherein the data provision device includes a vehicle interface configured to transmit data to and receive data from the vehicle, the data provision device is configured to transmit first data, which is a computer program or setting data, to be applied to the in-vehicle computer and a first expected value of the first data to the vehicle through the vehicle interface, wherein the first expected value is calculated by the data provision device using a key shared between the data provision device and the in-vehicle computer in advance; the in-vehicle computer includes: a first interface unit configured to transmit data to and receive data from a device outside the in-vehicle computer; a control unit configured to apply the first data provided by the data provision device to the in-vehicle computer, set the first expected value, which is provided by the data provision device as a second expected value for use in a secure boot, and execute the secure boot after applying the first data to the in-vehicle computer; and a measurement unit configured to, in the secure boot, calculate a measurement value of the first data applied to the in-vehicle computer using said shared key and verify the measurement value on the basis of the second expected value, a first interface unit configured to transmit data to and receive data from a device outside the in-vehicle computer; a control unit configured to apply the first data provided by the data provision device to the in-vehicle computer, set the first expected value, which is provided by the data provision device as a second expected value for use in a secure boot, and execute the secure boot after applying the first data to the in-vehicle computer; and a measurement unit configured to, in the secure boot, calculate a measurement value of the first data applied to the in-vehicle computer using said shared key and verify the measurement value on the basis of the second expected value, wherein the control unit is configured to transmit, through the first interface unit, a data application result indicating success or failure of application of the first data to the in-vehicle computer based on a result of the verification by the measurement unit, wherein the secure boot further comprises: advancing the execution of the first data if the data application result indicating success and stopping the execution of the the first data if the data application result indicating failure; the data provision device is configured to receive the data application result from the vehicle through the vehicle interface. advancing the execution of the first data if the data application result indicating success and stopping the execution of the the first data if the data application result indicating failure; the data provision device is configured to receive the data application result from the vehicle through the vehicle interface.