Using electrically programmable fuses to hide architecture, prevent reverse engineering, and make a device inoperable
View Patent ↗Techniques and systems whereby operation of and/or access to particular features of an electronic device may be controlled after the device has left the control of the manufacturer are provided. The operation and/or access may be provided based on values stored in non-volatile storage elements, such as electrically programmable fused (eFUSES).
1. A method for preventing unauthorized access to selected internal components of an integrated circuit device, comprising blowing at least one electrically programmable fuse in the integrated circuit device, wherein the electrically programmable fuse is configured to control externally generated communication between a communication interface of the integrated circuit device and the selected internal components of the integrated circuit device, and wherein blowing the electrically programmable fuse further comprises determining if a first unauthorized access attempt on the selected internal components has occurred, and blowing a first electrically programmable fuse associated with a first tamper bit if the first unauthorized access attempt is determined.
2. The method of claim 1 , wherein the electrically programmable fuse is positioned serially in a communication line between the communication interface of the integrated circuit device and the selected internal components of the integrated circuit device.
3. The method of claim 1 , wherein the electrically programmable fuse is positioned serially between an I/O pin of the selected internal components and devices positioned external to the integrated circuit device.
4. The method of claim 1 , further comprising disabling a portion of the functionality of the integrated circuit device in response to the blowing of the first electrically programmable fuse.
5. The method of claim 1 , further comprising determining if a second unauthorized access attempt on the selected internal components has occurred, and blowing a second electrically programmable fuse associated with a second tamper bit of the second unauthorized access attempt is determined.
6. The method of claim 5 , further comprising disabling all functionality of the integrated circuit device when the second tamper bit is blown.
7. The method of claim 6 , wherein disabling all functionality comprises disabling at least one of a clock signal, a multiplexer select, and an I/O line associated with the second electrically programmable fuse.
8. The method of claim 1 , wherein the communication interface comprises a device test interface and wherein the electrically programmable fuse is configured to disable access to onboard registers containing proprietary information via the device test interface after initial testing of the device by the manufacturer.
9. A method for preventing copying of proprietary information from an integrated circuit device, comprising:
determining if a first unauthorized access attempt to secure information on the integrated circuit device has occurred;
setting a first tamper bit if the first unauthorized access attempt is determined;
modifying a first device parameter in accordance with the first tamper bit;
determining if a second unauthorized access attempt to secure information in the integrated circuit device has occurred;
blowing a second tamper bit if the second unauthorized access attempt is determined; and
modifying a second device parameter that is different from the first device parameter in accordance with the second tamper bit.
10. The method of claim 9 , wherein the first and second tamper bits each comprise at least one electrically programmable fuse.
11. The method of claim 10 , wherein modifying the first device parameter comprises disabling a portion of the device functionality.
12. The method of claim 10 , wherein modifying the second device parameter comprises completely disabling functionality of the chip.
13. The method of claim 12 , wherein completely disabling functionality of the chip comprises disabling at least one of a clock signal, a multiplexer select, or an I/O line of the device in accordance with the second blown electrically programmable fuse.
14. The method of claim 10 , further comprising reading the first and second tamper bits on startup of the device and enabling functionality of the device in accordance with the first and second tamper bits.
15. The method of claim 10 , wherein the first and second tamper bits are read on startup of the device by a device controller, the device controller being configured to enable and disable functional modules of the device in accordance with the state of the first and second tamper bits.
16. The method of claim 12 , further comprising reprogramming electrically programmable fuses at the manufacturer to reset the first and second tamper bits and re-enable the functionality of the device.
17. The method of claim 16 , further comprising programming an electronic chip identification (ECID) into the electrically programmable fuses.