Integrated circuit with tamper detection circuit
View Patent ↗A tamper detection circuit for an integrated circuit includes a pseudo-random generator. A first line is connected to the output of the generator and a second line is connected in parallel via an inverter. A number of XOR gates are coupled to the first and second lines at locations along their length. Output from the XOR gates enables various general operational circuits of the integrated circuit. In the event of one of the lines being cut or otherwise tampered with then the output from the XOR gates will indicate a tamper state. The general operational circuits respond by either resetting or deleting critical data from memory such as the integrated circuit's authentication key. In a preferred version a number of trigger transistors connected to ground are inserted into the paths of the first line and the second line. A physical attack upon the integrated circuit causes a nearby trigger transistor to pull its attached line to ground thereby causing the output of local XOR gates to indicate a tamper state.
1. An integrated circuit having a tamper detection circuit including:
a noise generator circuit having a pseudo-random bit generator clocked at high speed relative to the general circuits of an integrated circuit;
a first line connected to the noise generator circuit; and
a second line connected to the noise generator circuit by an inverter;
wherein operation of one or more general circuits of the integrated circuit is dependent upon a logical combination of signals on the first line and the second line.
2. An integrated circuit according to claim 1 , wherein the logical combination of signals on the first line and the second line is implemented by one or more XOR gates coupled to the first line and the second line.
3. An integrated circuit according to claim 2 , wherein the first line and the second line are located in a layer vertically distanced from a layer containing general circuits of the integrated circuit.
4. An integrated circuit according to claim 3 , wherein the first line and the second line passes over the pseudo-random bit generator.
5. An integrated circuit according to claim 2 , wherein the one or more XOR gates comprise a plurality of XOR gates situated at a number of locations along said lines.
6. An integrated circuit according to claim 1 , wherein the one or more general circuits of the integrated circuit include memory circuits or key manipulation circuits.
7. An integrated circuit according to claim 1 , wherein a number of triggers are attached to one or more of the first line and the second line, each of the triggers being configured to alter a voltage on the first line or the second line to which it is attached in response to tampering on the integrated circuit.
8. An integrated circuit according to claim 7 , wherein the triggers comprise a number of transistors connected to ground.
9. An integrated circuit according to claim 7 , wherein one or more of the general circuits is reset in response to the logical combination of signals on the first and second lines.
10. An integrated circuit according to claim 7 , wherein one of the general circuits comprises a memory circuit containing an authentication key and wherein the memory circuit erases the authentication key in response to the logical combination of the signals on the first and second line.
11. An integrated circuit including a number of general circuits and a tamper detection circuit to which said general circuits are responsive, the tamper detection circuit including:
a pseudo random bit generator clocked at high speed relative to the general circuits of the integrated circuit;
a first line connected to the pseudo-random bit generator and disposed in a layer vertically displaced relative to a layer containing the general circuits; and
a second line connected to the random bit source and disposed in a layer vertically displaced relative to the layer containing the general circuits;
a number of XOR gates coupled at locations along the first line and the second line;
a plurality of triggers attached to the first line and to the second line each of the triggers being configured to alter a voltage on the first line or the second line to which it is attached in response to tampering on the integrated circuit.