Secure electronic circuitry with tamper detection
A circuit board is protected by being enclosed in a security housing that includes conductive tamper traces running along its interior surface, the conductive tamper traces being a housing portion of a tamper detection circuit. The tamper detection circuit also includes a board portion that detect tampering with the tamper detection circuit by monitoring voltages at monitor nodes along the board portion. The board portion of the tamper detection circuit is connected to the tamper traces via multiple connector pieces. The connector pieces can be held in place by board connector piece holders affixed to the board or housing connector piece holders of the housing. When tampering is detected, it can be localized based on voltages measured at multiple recesses along the housing. The tamper detection circuit can be arranged in a wheatstone bridge layout for environmental tolerance. The circuit board's functions/components can be disabled if tampering is detected.
1. A system for securing electronics, the system comprising:
a housing for a circuit board that is configured to cover at least a portion of the circuit board, wherein the housing is distinct from the circuit board;
a first tamper trace that runs at least from a first connection node of the housing to a second connection node of the housing, wherein the first tamper trace is configured to couple to a first set of connection nodes of the circuit board through the first connection node of the housing and the second connection node of the housing; and
a second tamper trace that runs at least from a third connection node of the housing to a fourth connection node of the housing, wherein the second tamper trace is configured to couple to a second set of connection nodes of the circuit board through the third connection node of the housing and the fourth connection node of the housing, wherein a first part of a tamper detection circuit includes the first tamper trace and the second tamper trace, wherein a second part of the tamper detection circuit is configured to be included on the circuit board, wherein the tamper detection circuit is configured to include a first leg and a second leg that are configured to be connected in parallel, wherein the first leg includes the first tamper trace of the housing and a first monitor node of the second part of the tamper detection circuit that is configured to monitor a voltage of the first tamper trace, and wherein the second leg includes the second tamper trace of the housing and a second monitor node of the second part of the tamper detection circuit that is configured to monitor a voltage of the first tamper trace.
2. The system of claim 1 , further comprising:
the circuit board.
3. The system of claim 1 , wherein the tamper detection circuit is configured to include a wheatstone bridge circuit in which the first leg and the second leg are connected in parallel.
4. The system of claim 1 , wherein the tamper detection circuit is configured to monitor a differential voltage between the first monitor node and the second monitor node to determine whether the tamper detection circuit has been tampered with.
5. The system of claim 1 , wherein the first leg of the tamper detection circuit and the second leg of the tamper detection circuit are configured to conduct different voltages unless tampered with.
6. A system for securing electronics, the system comprising:
a housing for circuitry, wherein the housing is distinct from the circuitry;
a first tamper trace that runs at least from a first connection node of the housing to a second connection node of the housing, wherein the first tamper trace is configured to couple to a first set of connection nodes of the circuitry through the first connection node of the housing and the second connection node of the housing; and
a second tamper trace that runs at least from a third connection node of the housing to a fourth connection node of the housing, wherein the second tamper trace is configured to couple to a second set of connection nodes of the circuitry through the third connection node of the housing and the fourth connection node of the housing, wherein a first part of a tamper detection circuit includes the first tamper trace and the second tamper trace, wherein a second part of the tamper detection circuit is configured to be included in the circuitry, wherein the tamper detection circuit is configured to include a first leg and a second leg that are configured to be connected in parallel, wherein the first leg includes the first tamper trace of the housing and a first monitor node of the second part of the tamper detection circuit that is configured to monitor a voltage of the first tamper trace, and wherein the second leg includes the second tamper trace of the housing and a second monitor node of the second part of the tamper detection circuit that is configured to monitor a voltage of the first tamper trace.
7. The system of claim 6 , further comprising:
the circuitry.
8. The system of claim 6 , wherein the circuitry includes a circuit board.
9. The system of claim 6 , wherein the tamper detection circuit is configured to include a wheatstone bridge circuit in which the first leg and the second leg are connected in parallel.
10. The system of claim 6 , wherein the tamper detection circuit is configured to monitor a differential voltage between the first monitor node and the second monitor node to determine whether the tamper detection circuit has been tampered with.
11. The system of claim 6 , wherein the first leg of the tamper detection circuit and the second leg of the tamper detection circuit are configured to conduct different voltages unless tampered with.
12. The system of claim 6 , further comprising:
a first connector piece configured to couple the first connection node of the housing to a first connection node of the first set of connection nodes of the circuitry;
a second connector piece configured to couple the second connection node of the housing to a second connection node of the first set of connection nodes of the circuitry;
a third connector piece configured to couple the third connection node of the housing to a first connection node of the second set of connection nodes of the circuitry; and
a fourth connector piece configured to couple the fourth connection node of the housing to a second connection node of the second set of connection nodes of the circuitry.
13. The system of claim 6 , wherein the housing lacks a direct wired connection between the first tamper trace and the second tamper trace unless tampered with.
14. The system of claim 6 , wherein the first tamper trace and the second tamper trace are both partially covered with an insulative coating other than at least one recess in the housing.
15. The system of claim 6 , wherein the first tamper trace is configured to snake around at least one surface of the housing, and wherein the second tamper trace is also configured to snake around the at least one surface of the housing.
16. The system of claim 6 , wherein at least a portion of the first tamper trace is configured to be parallel to at least a portion of the second tamper trace.
17. The system of claim 6 , wherein at least a portion of the first tamper trace is configured to be perpendicular to at least a portion of the second tamper trace.
18. The system of claim 6 , wherein the first leg of the tamper detection circuit is configured to include at least a first resistor, and wherein the second leg of the tamper detection circuit is configured to include at least a second resistor.
19. The system of claim 6 , wherein the tamper detection circuit is configured to develop parasitic resistances symmetrically between the first leg and the second leg so mitigate effects of the parasitic resistances on differential voltage between the first leg and the second leg.
20. A method of for securing electronics, the method comprising:
monitoring a tamper detection circuit using a first monitor node and a second monitor node to determine whether the tamper detection circuit has been tampered with, wherein the tamper detection circuit includes a first tamper trace that runs at least from a first connection node of a housing to a second connection node of the housing, wherein the housing is for circuitry, wherein the housing is distinct from the circuitry, wherein the first tamper trace is configured to couple to a first set of connection nodes of the circuitry through the first connection node of the housing and the second connection node of the housing, wherein the tamper detection circuit includes a second tamper trace that runs at least from a third connection node of the housing to a fourth connection node of the housing, wherein the second tamper trace is configured to couple to a second set of connection nodes of the circuitry through the third connection node of the housing and the fourth connection node of the housing, wherein a first part of a tamper detection circuit includes the first tamper trace and the second tamper trace, wherein a second part of the tamper detection circuit is configured to be included in the circuitry, wherein the tamper detection circuit is configured to include a first leg and a second leg that are configured to be connected in parallel, wherein the first leg includes the first tamper trace of the housing and a first monitor node of the second part of the tamper detection circuit that is configured to monitor a voltage of the first tamper trace, and wherein the second leg includes the second tamper trace of the housing and a second monitor node of the second part of the tamper detection circuit that is configured to monitor a voltage of the first tamper trace.