Point of sale terminal having pulsed current tamper control sensing
First Claim
1. A point of sale terminal, comprising:
- a tamper conductive mesh comprising a plurality of wire pairs; and
an integrated circuit including a processor, a tamper detect circuit and a tamper detect terminal, wherein the tamper conductive mesh is connected to the tamper detect terminal, the tamper detect circuit including a current source and causing a pulse of current to flow through the current source and through the tamper detect terminal and through the tamper conductive mesh, the tamper detect circuit determining whether when the pulse of current is flowing a voltage on the tamper detect terminal is both below a predetermined upper bias voltage and above a predetermined lower bias voltage indicative of tampering by alteration of the conductive mesh pairs.
2 Assignments
0 Petitions
Accused Products
Abstract
A point of sale terminal includes a microcontroller integrated circuit. In one aspect, a regulator within the IC receives power from a supply voltage terminal and/or a battery terminal. If the regulator does not receive adequate power from either terminal, then energy stored on-chip in a capacitor is used to erase secure memory. In another aspect, pulses of current are made to pulse through conductors of a conductive mesh. A tamper condition is detected if an improper voltage is detected on the IC terminal through which the pulse is conducted. In another aspect, each vendor signs his/her firmware with his own vendor ID. A bootloader uses the vendor ID to lookup a public key that is then used to verify a private key supplied by the firmware to be executed. In another aspect, a magnetic card reader includes a digital peak detector circuit involving programmable positive and negative thresholds.
-
Citations
23 Claims
-
1. A point of sale terminal, comprising:
-
a tamper conductive mesh comprising a plurality of wire pairs; and an integrated circuit including a processor, a tamper detect circuit and a tamper detect terminal, wherein the tamper conductive mesh is connected to the tamper detect terminal, the tamper detect circuit including a current source and causing a pulse of current to flow through the current source and through the tamper detect terminal and through the tamper conductive mesh, the tamper detect circuit determining whether when the pulse of current is flowing a voltage on the tamper detect terminal is both below a predetermined upper bias voltage and above a predetermined lower bias voltage indicative of tampering by alteration of the conductive mesh pairs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A point of sale terminal, comprising:
-
a tamper conductive mesh comprising a plurality of wire pairs; and an integrated circuit including a processor, a tamper detect circuit, a first register and a tamper detect terminal, wherein the tamper conductive mesh is connected to the tamper detect terminal, the tamper detect circuit including a current source and causing a pulse of current to flow through the current source and through the tamper detect terminal and through the tamper conductive mesh, wherein the pulse of current starts at a first time, wherein the integrated circuit samples the voltage on the tamper detect terminal at a second time after the first time, wherein a time difference between the first time and the second time is programmable by the processor, wherein the time difference between the first time and the second time is a function of a value stored in the first register, and wherein the tamper detect circuit determines whether a voltage on the tamper detect terminal is in a predetermined acceptable range when the pulse of current is flowing indicative of tampering by alteration of the conductive mesh pairs. - View Dependent Claims (11, 12)
-
-
13. A point of sale terminal, comprising:
-
a tamper conductive mesh comprising a plurality of wire pairs; and an integrated circuit including a processor, a tamper detect circuit and a tamper detect terminal, wherein the tamper conductive mesh is connected to the tamper detect terminal, the tamper detect circuit including a current source and causing a pulse of current to flow through the current source and through the tamper detect terminal and through the tamper conductive mesh, the tamper detect circuit determining whether a voltage on the tamper detect terminal is in a predetermined acceptable range when the pulse of current is flowing, and wherein said determining involves comparing the voltage on the tamper detect terminal to a first programmable bias voltage and also involves comparing the voltage on the tamper detect terminal to a second programmable bias voltage indicative of tampering by alteration of the conductive mesh pairs.
-
-
14. A point of sale terminal, comprising:
-
a tamper conductive mesh comprising a plurality of wire pairs; and an integrated circuit including a processor, a tamper detect circuit and a tamper detect terminal, wherein the tamper conductive mesh is connected to the tamper detect terminal, the tamper detect circuit including a current source and causing a pulse of current to flow through the current source and through the tamper detect terminal and through the tamper conductive mesh, wherein the tamper detect circuit determines whether a voltage on the tamper detect terminal is in a predetermined acceptable range when the pulse of current is flowing, and wherein the tamper detect circuit also determines whether a voltage on the tamper detect terminal is in a second predetermined acceptable range when the pulse of current is not flowing indicative of tampering by alteration of the conductive mesh pairs.
-
-
15. A method comprising:
-
(a) storing a first value and a second value in an integrated circuit; (b) starting to draw a pulse of current through a tamper detect terminal and into the integrated circuit, the pulse starting at a first time, the tamper detect terminal connected to a tamper conductive mesh responsive to a tampering event; (c) at a second time, after the first time and while the pulse is being drawn, sampling a voltage on the tamper detect terminal and determining whether the voltage is in a first acceptable voltage range, wherein a time difference between the first time and the second time is at least in part determined by the first value; (d) stopping the pulse of current at a third time; (e) at a fourth time after the third time sampling a voltage on the tamper detect terminal and determining whether the voltage is in a second acceptable voltage range, wherein a time difference between the third time and the fourth time is at least in part determined by the second value; and (f) detecting the tampering event based on (c) and (e). - View Dependent Claims (16, 17, 18, 19, 20, 21)
-
-
22. A point of sale terminal, comprising:
-
a tamper conductive mesh comprising a plurality of wire parts; and an integrated circuit including a processor, a tamper detect circuit and a tamper detect terminal, wherein the tamper detect terminal is coupled to an inverting input lead of a first comparator and to a non-inverting input lead of a second comparator, wherein the tamper conductive mesh is connected to the tamper detect terminal, the tamper detect circuit including a current source and causing a pulse of current to flow through the current source and through the tamper detect terminal and through the tamper conductive mesh, the tamper detect circuit determining whether a voltage on the tamper detect terminal is in a predetermined acceptable range when the pulse of current is flowing indicative of tampering by alteration of the conductive mesh pairs. - View Dependent Claims (23)
-
Specification