Method and apparatus for authorizing unlocking of a device
A programmable integrated circuit device includes a programmable core, a boot device configured to boot up the programmable core, and a one-time programmable memory module controlling life cycle states of the programmable integrated circuit device, including (i) an operational state during which programming resources of the programmable device are locked, and (ii) an inspection state in which the programming resources of the programmable device are accessible. The one-time programmable memory module is configured to allow unidirectional advance from the operational state to the inspection state, when authorized by a lock control circuit responsive to control signals from the boot device to authorize the unidirectional advance from the operational state to the inspection state. Authorization of the unidirectional advance may be limited to a time interval during a boot cycle of the programmable device. The unidirectional advance may be based on receipt of an authenticated request from a requester.
1. A programmable integrated circuit device comprising:
a programmable core;
a boot device configured to boot up the programmable core; and
a one-time programmable memory module comprising a lock control circuit, the one-time programmable memory module controlling life cycle states of the programmable integrated circuit device, the life cycle states of the one-time programmable integrated circuit device including (i) a state during which user functions of the programmable integrated circuit device are operational and programming resources of the programmable integrated circuit device are locked, and (ii) an inspection state during which the programming resources of the programmable integrated device are accessible and user functions of the programmable integrated circuit device are inaccessible; wherein:
the one-time programmable memory module is configured to allow unidirectional advance, when authorized, from the state during which user functions of the programmable integrated circuit device are operational state to the inspection state, the unidirectional advance preventing return of the programmable integrated circuit device from the inspection state to the state during which user functions of the programmable integrated circuit device are operational; and
the lock control circuit of the one-time programmable memory module is responsive to control signals from the boot device to authorize the unidirectional advance from the operational state to the inspection state.
2. The programmable integrated circuit device of claim 1 , wherein the boot device outputs a first one of the control signals, the first one of the control signals limiting, to a time interval during a boot cycle of the programmable integrated circuit device, authorization of the unidirectional advance from the operational state to the inspection state.
3. The programmable integrated circuit device of claim 2 , wherein the time interval is coterminous with the boot cycle.
4. The programmable integrated circuit device of claim 2 , wherein the time interval begins at a predetermined time after the boot cycle begins.
5. The programmable integrated circuit device of claim 2 , wherein the time interval ends at a predetermined time before the boot cycle ends.
6. The programmable integrated circuit device of claim 2 , wherein the boot device is configured to output a second one of the control signals, during the time interval, to authorize the unidirectional advance from the operational state to the inspection state, based on receipt of a request from a requester.
7. The programmable integrated circuit device of claim 6 , wherein the boot device is configured to output the second one of the control signals only when the request includes authenticated credentials.
8. The programmable integrated circuit device of claim 7 , wherein the boot device is configured to output the second one of the control signals only when the request is verified to be targeted at the programmable integrated circuit device.
9. The programmable integrated circuit device of claim 8 , further comprising:
an unalterable memory having a unique identifier stored therein; wherein:
the boot device is configured to verify that the request is targeted at the programmable integrated circuit device by comparing an identifier in the request to the unique identifier stored in the unalterable memory.
10. The programmable integrated circuit device of claim 8 , wherein the boot device is configured to verify that the request is targeted at the programmable integrated circuit device by:
generating a random number;
sending the generated random number to the requester;
receiving a digitally signed random number from the requester; and
comparing the digitally signed random number to the generated random number.
11. The programmable integrated circuit device of claim 1 , wherein the boot device is further configured to, after authorizing the unidirectional advance from the operational state to the inspection state, signal the one-time programmable memory to initiate the unidirectional advance from the operational state to the inspection state.
12. The programmable integrated circuit device of claim 1 , wherein the one-time programmable memory is fuse-based.