# US 11,113,698 B2 · Line-based chip card tamper detection

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- Number: US 11,113,698 B2
- Document ID: US11113698B2
- Status: Granted
- Kind: B2
- Application number: 16/810,700
- Filed: 2020-03-05
- Published: 2020-06-25
- Granted: 2021-09-07
- Earliest claimed: 2017-02-22
- Assignees: Square, Inc.
- Applicants: Square, Inc.
- Inventors: Afshin Rezayee; Malcolm Smith; Yue Yang; Jeremy Wade; Max Guise; Kamran Sharifi
- Web page: https://patentgrep.com/patent/US11113698B2

## CPC

- G06Q 20/409: {Device specific authentication in transaction processing}
- G07F 7/12: Card verification
- G06Q 20/102: {Bill distribution or payments}
- G06Q 20/341: {Active cards, i.e. cards including their own processing means, e.g. including an IC or chip}
- G06Q 20/4016: {involving fraud or risk level assessment in transaction processing}
- G07F 7/0873: {Details of the card reader}
- G06Q: INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
- G07F: COIN-FREED OR LIKE APPARATUS (coin sorting G07D3/00; coin testing G07D5/00; {handling coins or paper currencies apart from payment activated apparatus G07D; payment architectures, schemes or protocols G06Q20/00})

## Abstract

A payment processing device can implement a monitoring system to detect for tamper attempts at a chip card interface. The monitoring system can establish a baseline when no chip card is present in the chip card interface, or in some embodiments, when it is known that an authentic chip card 14 is present in the slot 21. During subsequent evaluations of the chip card interface by the monitoring system, a response received by the monitoring system that deviates from the baseline can indicate that a tamper attempt at the chip card interface may have occurred. If a tamper attempt is determined by the monitoring system, a remedial or corrective action can be taken.

## Claims

### Claim 1

A payment reader for exchanging payment information with a chip card and for providing decoy data to a tamper device connected to a chip card interface of the payment reader, comprising:
a chip card interface comprising at least a voltage interface, a reset interface, a clock interface,
an input/output interface, a ground interface, and a programming interface;
a processing unit coupled to the chip card interface and configured to execute instructions;
a plurality of chip card lines coupled between the chip card interface and the processing unit, comprising:
a voltage line coupled between the voltage interface and the processing unit;
a reset line coupled between the reset interface and the processing unit;
a clock line coupled between the clock interface and the processing unit;
an input/output line coupled between the input/output interface and the processing unit;
a ground line coupled between the ground interface and the processing unit; and
a programming line coupled between the programming interface and the processing unit; and
the input/output interface comprising:
a reader communication circuit coupled to the input/output line, the reader communication circuit configured to operate at a first clock frequency;
a card communication circuit coupled to the input/output line, the card communication circuit configured to operate at a second clock frequency;
a memory having the instructions stored thereon and coupled to provide the instructions to the processing unit, wherein the instructions cause the processing unit to:
transmit data over the input/output line with the card communication circuit at the second clock frequency;
read data from the input/output line with the reader communication circuit at the first clock frequency; and
transmit decoy data over the input/output line with the reader communication circuit after expiration of a first period for the first clock frequency and before an expiration of a second period for the second clock frequency.

### Claim 2 (depends on 1)

The payment reader of claim 1, wherein the card communication circuit transmits data by opening and closing a switch coupled to the input/output line and a bias voltage to change a state of the input/output line between ground and the bias voltage.

### Claim 3 (depends on 1)

The payment reader of claim 1, wherein the decoy data includes at least one of jammer signals, noise, or clock jitters.

### Claim 4 (depends on 1)

The payment reader of claim 1, wherein the second clock frequency is at least 40 times less than the first clock frequency.

### Claim 5

A transaction device for exchanging information with a chip card comprising:
a contact interface comprising a plurality of pins, wherein the plurality of pins includes an input/output pin;
a processing unit coupled to the contact interface;
a plurality of contact lines coupled between the plurality of pins of the contact interface and the processing unit; and
a monitoring system coupled to the contact line for the input/output pin, the monitoring system comprising a reader communication circuit configured to transmit data from the processing unit to the chip card and to alter a data communication sequence between the processing unit and the chip card such that a tamper device connected to the input/output pin is unable to interpret extracted data from the input/output pin.

### Claim 6 (depends on 5)

The transaction device of claim 5, wherein the plurality of pins further includes a reset pin, the monitoring system further comprises a card communication circuit configured to transmit data from the chip card to the processing unit, and the monitoring system is configured to interrupt a data transmission by the card communication circuit by sending a reset signal to the reset pin, the card communication circuit configured to restart transmitting data after a predetermined time period has elapsed.

### Claim 7 (depends on 6)

The transaction device of claim 6, wherein the reader communication circuit is configured to transmit additional data to the input/output pin during the predetermined time period, wherein the tamper device is unable to interpret extracted data that includes the additional data.

### Claim 8 (depends on 7)

The transaction device of claim 7, wherein the additional data includes at least one of jammer signals, noise, or clock jitters.

### Claim 9 (depends on 5)

The transaction device of claim 5, wherein the monitoring system further comprises a card communication circuit configured to transmit data from the chip card to the processing unit, and wherein a clock frequency of the reader communication circuit is greater than a clock frequency of the card communication circuit.

### Claim 10 (depends on 9)

The transaction device of claim 9, wherein the reader communication circuit is configured to transmit additional data to the input/output pin after reading data transmitted by the card communication circuit and before the card communication circuit transmits additional data, wherein the tamper device is unable to interpret extracted data that includes the additional data.

### Claim 11 (depends on 9)

The transaction device of claim 9, wherein the clock frequency of the reader communication circuit is at least 10 times greater than a clock frequency of the card communication circuit.

### Claim 12 (depends on 5)

The transaction device of claim 5, wherein the reader communication circuit is further configured to detect for a tamper attempt at the input/output pin.

### Claim 13 (depends on 12)

The transaction device of claim 12, wherein the reader communication circuit is configured to change a state of the contact line coupled to the input/output pin and to detect for a subsequent change of state of the contact line coupled to the input/output pin, wherein the subsequent change of state of the contact line indicates the presence of the tamper device.

### Claim 14 (depends on 13)

The transaction device of claim 13, wherein the reader communication circuit changes the state of the contact line coupled to the input/output pin at a time period when the chip card is unable to read data.

### Claim 15 (depends on 5)

The transaction device of claim 5, wherein the monitoring system further comprises a card communication circuit configured to transmit data from the chip card to the processing unit, and the monitoring system is configured to change a clock frequency used by the reader communication circuit and the card communication circuit at a predefined interval.

### Claim 16

A method of obfuscating data extracted by a tamper device connected to a transaction device, the method comprising:
interfacing a chip card with a contact interface of a transaction device, wherein the contact interface includes an input/output interface;
communicating data between the chip card and a processing unit of the transaction device via the input/output interface;
monitoring a contact line connecting the input/output interface and the processing unit with a monitoring system, wherein the monitoring system has a reader communication circuit configured to transmit data from the processing unit to the chip card; and
altering, by the reader communication circuit, a data communication sequence between the processing unit and the chip card such that a tamper device connected to the transaction device is unable to interpret extracted data from the transaction device.

### Claim 17 (depends on 16)

The method of claim 16, wherein the contact interface further includes a reset interface, the monitoring system further comprises a card communication circuit configured to transmit data from the chip card to the processing unit, and the altering the data communication sequence includes:
sending a reset signal to the reset interface to interrupt a data transmission by the card communication circuit;
transmitting, by the reader communication circuit, additional data to the input/output interface after the interruption of the data transmission, wherein the tamper device is unable to interpret extracted data that includes the additional data; and
restarting the data transmission by the card communication circuit after the transmission of the additional data by the reader communication circuit.

### Claim 18 (depends on 16)

The method of claim 16, wherein the monitoring system further comprises a card communication circuit configured to transmit data from the chip card to the processing unit and the altering the data communication sequence includes:
operating the card communication circuit at a first clock frequency;
operating the reader communication circuit at a second clock frequency at least two times greater than the first clock frequency; and
transmitting, by the reader communication circuit, additional data to the input/output interface after reading data transmitted by the card communication circuit and before the card communication circuit transmits additional data, wherein the tamper device is unable to interpret extracted data that includes the additional data.

### Claim 19 (depends on 16)

The method of claim 16, wherein the monitoring system further comprises a card communication circuit configured to transmit data from the chip card to the processing unit, and the altering the data communication sequence includes changing a clock frequency used by the reader communication circuit and the card communication circuit at a predefined interval.

### Claim 20 (depends on 16)

The method of claim 16, further comprising detecting for a tamper attempt at the input/output interface with the reader communication circuit.