WO2014169393A1

WO2014169393A1 - Security switch for an rfid token

Info

Publication number: WO2014169393A1
Application number: PCT/CA2014/050386
Authority: WO
Inventors: Aidan MCDOWELL
Original assignee: Mcdowell Aidan
Priority date: 2013-04-18
Filing date: 2014-04-17
Publication date: 2014-10-23

Abstract

There is described a radiofrequency identification (RFID) token comprising an RFID tag, a security switch, and a contact switch, wherein exposure of the RFID tag to an unauthorized scanner in the absence of activation of the contact switch activates the security switch to prevent retransmission of an RFID signal from the token.

Description

SECURITY SWITCH FOR AN RFID TOKEN

FIELD OF THE INVENTION

[0001] The present invention pertains to a security switch for a radio frequency identification (RFID) token. More particularly, the present invention pertains to a switch on an RFID token which prevents unauthorized scanners from receiving data from an RFID token in the absence of human contact.

BACKGROUND

[0002] An RFID token is a device which employs an RFID tag to embed information.

RFID tokens can be active, using a power source such as a battery, or passive wherein retransmission from the RFID tag requires the receipt of a signal from an outside power source such an RFID scanner.

[0003] RFID tokens are commonly used in a variety of financial and security devices and instruments. Some exemplary RFID tokens are credit cards, debit cards, medical record cards, driver's licenses, government issued identification cards, passports, toll collection devices, pass or security cards or fobs, and rapid point-of-sale tokens such as gas or coffee fobs. Such RFID tokens generally store the private information of a user, as well as often a key or keys to accessing such information. Developments in radio frequency identification (RFID) technology continue to yield larger memory capacities, wider reading ranges, and faster processing.

[0004] One benefit of contactless RFID tokens is that they can be used without bringing the token into direct contact with a reader. RFID technology is prone to data theft since RFID tags are often remotely accessible to rogue scanners. Because such contactless devices can be read at a distance, a suitable transmitter and receiver can surreptitiously obtain information from the token even when hidden from view, such as when it is being stored in a personal bag or pocket. Particularly, unauthorized scanners can attempt to gain access to the data stored on the RFID token by bypassing any security features incorporated therein, particularly by attempting to energize RFID the token so it will retransmit the stored data In the absence of a security feature on the RFID token, malicious tracking of an individual or theft of personal information from the RFID token can occur.

[0005] United States Patent No. 6,863,220, incorporated herein by reference, describes contactless information storage devices, such as RFID payment cards, that are protected against unauthorized misuse by employing an internal mechanism that normally disables the on-card electronic circuitry until the mechanism is intentionally actuated by the cardholder.

[0006] United States Patent No. 7,994,920, incorporated herein by reference, discloses an active RFID token with a touch sensitive screen coupled to a power source wherein the touch screen acts as a switch to operate the power in the token only when touched. In one example, an RFID-enabled card comprises an electrode installed on one or both faces of the card or imbedded on the edge of the card. However, touch contact from a user holding the card for extended periods of time while waiting to pay for purchases occur before the token circuitry is energized can leave the card open for data mining or social engineering attacks from unauthorized RF scanners, for example in busy stores where the user has their RFID enabled credit card in their hand while waiting to approach the sales register.

[0007] There remains a need for improving the security measures for preventing the unauthorized transfer of information from RFID tokens by unauthorized scanners.

[0008] This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.

SUMMARY OF THE INVENTION

[0009] An object of the present invention is to provide a temporary automatic deactivation of an RFID token in the presence of an unauthorized RFID scanner.

[0010] In one aspect, there is provided a radiofrequency identification (RFID) token comprising an RFID tag; a security switch operatively connected to the RFID tag; and a contact switch operatively connected to the security switch, wherein exposure of the RFID tag to an unauthorized scanner in the absence of activation of the contact switch activates the security switch to prevent retransmission of an RFID signal from the token.

[0011] In one embodiment, the security switch comprises a resistor. In another embodiment, the security switch comprises a reset pin.

[0012] In another embodiment, the RFID token further comprises alert means activated by the security switch. In another embodiment, the alert means comprises an LED, vibrator, or a screen.

[0013] In another embodiment, the contact switch is a capacitive switch or a mechanical switch.

[0014] In another embodiment, the RFID token comprises a battery.

[0015] In another embodiment, the RFID tag is passive and does not comprise an external power source, such as a battery.

[0016] In another embodiment, the RFID token is encapsulated in a protective housing.

[0017] In accordance with another aspect, there is provided a radio frequency identification (RFID) sensor comprising an RFID tag; a security switch operatively connected to the RFID tag; and alert means for indicating that the security switch has been activated by an unauthorized scanner, wherein exposure of the RFID tag to an unauthorized scanner activates the security switch to prevent retransmission of an RFID signal from the device.

[0018] In one embodiment, the RFID sensor further comprises a read-write memory for recording information about the details of activation of the security switch. In another embodiment, the details of activation of the security switch include the day, time, signal strength and/or signal frequency of the unauthorized scanner.

[0019] In another embodiment, the RFID sensor further comprises transmission means for transmitting a signal comprising the details of activation of the security switch.

[0020] In another embodiment, the alert means on the RFID sensor is an LED, a vibrator, or a screen. BRIEF DESCRIPTION OF THE FIGURES

[0021] For a better understanding of the present invention, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where:

[0022] Figures 1A-1E depict circuitry diagrams of five exemplary embodiments of the present invention;

[0023] Figure 2 depicts a flow diagram of the presently described RFID security- enhanced token;

[0024] Figures 3A-3D depict different configurations for conductive contact switches for an RFID card;

[0025] Figures 4A-4C depict configurations for RFID fob having a capacitive switch

(4A), button (4B) and button with LED alert (4C);

[0026] Figure 5 depicts an exemplary attack by an unauthorized RF scanner at a retail establishment.

DETAILED DESCRIPTION OF THE INVENTION [0027] Definitions

[0028] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0029] As used in the specification and claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise.

[0030] The term "comprising" as used herein will be understood to mean that the list following is non-exhaustive and may or may not include any other additional suitable items, for example one or more further feature(s), component(s) and/or element(s) as appropriate.

[0031] As used herein the term "scanner" when used in the context of RFID means a device that can execute transmitting and receiving functions for obtaining data from an RFID tag or token. Some examples of scanners include but are not limited to point-of-sale devices and security devices such as door locks. Other optionally portable scanners for verification of fare payments include but are not limited to Near Field Communication (NFC) scanners such as the devices installed in new smartphones, RFID area scanners such as the kinds used to track/locate asset control tags, and generic RFID scanners for fixed installations.

[0032] As used herein, the term "unauthorized scanner" is any scanner that can obtain data from an RFID tag or tokens against the wishes of or without the knowledge of the owner or user of the RFID tag or token.

[0033] As used herein, the term "radio frequency" or "RF" pertains to signals transmitted and received in the radio range. Specifically, these are in the frequency of radio waves, and the alternating currents which carry radio signals.

[0034] As used herein, the term "antenna" is used interchangeably with the term

"transceiver" and refers to a component in the RFID token that can receive and transmit signals. This element refers to both propagating systems as well as inductive systems.

[0035] As used herein, the term "RFID token" refers to a device comprising RFID circuitry for receiving and re-transmitting RF signal to a scanner. Some non-limiting examples of RFID tokens are credit cards, debit cards, medical record cards, driver's licenses, government issued identification cards, passports, toll collection devices, pass or security cards or fobs, and rapid point-of-sale tokens such as gas or coffee fobs.

[0036] As used herein, the term "operatively connected" describes the functional relationship between two or more components in the system. This term is intended to mean that the identified components are connected in a way to perform a designated function. The operatively connected components can be physically or electrically connected, but are not necessarily connected by a physical attachment. This term covers physically connected components, such as for example a standard wired electrical connection, and non-physically connected components.

[0037] The terms "human contact" and "human interaction" are understood to encompass any interaction between the RFID token and a person. The interaction can be direct, such as, for example, through pressure or touch, or indirect such as, for example, by a non-touch gesture or heat. These terms refer to proximity interaction with or without direct contact with a person.

[0038] Security of RFID tokens can be increased without requiring modification of existing RFID scanners or encumbering the data transmission protocol to authorized RFID scanning devices, such as point-of-sale and security lock devices. This added security is accomplished by the inclusion of two additional pieces of circuitry to the RFID token:

1. a contact switch; and

2. a security switch.

With this circuitry, the activation process of the token is made procedural wherein the contact switch must be activated before an RFID scanner is able to energize the RFID token circuitry, and the security switch must be not be enabled. Without both conditions being met, the security switch will not enable the token to be energized by the scanner and therefore will not return the RFID data to the scanner.

[0039] Security Switch

[0040] The RFID token comprises a security switch that is activated or charged in the presence of an unauthorized RFID signal or scanner in the absence of activation of the contact switch. The security switch will therefore shunt the signal or charge from the RFID transmitter or antenna to prevent transmission of data in response to an unauthorized scanner. This charge bypass route enables the RFID token to ensure a safe environment prior to data transmission, and includes circuitry that does not impede intentional normal use of the RFID token.

[0041] The security switch preferably comprises a circuit capable of being charged by the field induced by an RF scanner. In practice, a user will make touch contact with the token before the token enters the range of the intended RFID scanner. This is accomplished by establishing the resistance in the circuit pathway such that with the touch switch in the closed position the current on the "disabling" pathway is not sufficient to disable the RFID token.

[0042] The inclusion of a capacitor on the new circuitry also provide additional protection against data extraction by rogue or unauthorized RFID scanners operating in a "pulsing" configuration. By using a capacitor the "reset" time for the circuit can be lengthened so that there is a delay in the reset after the energizing signal is removed. The size of the capacitor can vary, providing a variable reset time for the security switch. By varying the security switch reset time, the unauthorized RFID scanner cannot just be configured to pulse on and off to bypass this security feature. Allowing slight variations in the time to discharge in the capacitor, making each token have a differing reset interval ensures that "pulsing" rogue RFID scanners cannot be easily set to pulse in time with an absolute token reset interval. Specifically, keeping the temporary disabling feature of the token active for a set period of time after the RFID token is removed from the rogue RFID scanners range makes it more difficult for the unauthorized scanner to transmit and then receive signal from security switches having variable reset time. The reset time for the security switch can range from being essentially instantaneous to one or more seconds.

[0043] The technical difference between a user triggering the contact switch in a hostile environment compared to a verified environment is as follows. When the user triggers the contact switch in a hostile environment, the contact switch is impeded from closing the circuit pathway between the antenna that collects the RF charge and the RFID transponder circuitry. This is due to the resistance on the circuit pathway preceding the contact switch reaching a sufficient level that it follows a circuit pathway that triggers a "reset" pin on the contact switch. This feature works to ensure that security of the token isn't bypassed by the unauthorized scanner. When a user triggers the contact switch in a verified environment, the resistance is below the threshold required to follow the circuitry pathway to the reset pin on the switch, allowing for the switch to be closed and connect the antenna collecting the RF charge to the RFID transponder circuitry. In this way the token is protected from

unauthorized scanners in that the user is not able to inadvertently engage the card for an unintended scanner while intending to use the card at a legitimate scanner.

[0044] The security switch can also be configured to switch off for a period of time subsequent to an unauthorized scanning attempt. The reset time range is only limited by the physical size limitations to the capacitors for the circuitry. The delay could be fractions of a second to minutes if a sufficiently large capacitor is included to provide power to the circuitry, thus keeping the reset pin active.

[0045] Another optional feature of the security switch can include a limited-use switch. The limited-use switch can be configured to automatically and permanently or semipermanently switch off after a specified number of unsolicited RFID attempts. The RFID token can then be rendered temporarily or permanently disabled, or may be reactivated upon validation by the user or other means. This can be implemented by using additional circuit pathways that burn out or shut off after a specified amount of usage. Accordingly, additional circuitry could potentially also be added so that each use of the new circuitry burns out a supplementary circuit such that after a specified number of uses the circuit fails and the card is permanently disabled, thus prompting the user to report the token failure to the issuing agency. Optional read-write memory can also record the details of each burn out or shut off.

[0046] Contact Switch

[0047] The contact switch on the RFID token enables the user to enable transmission of data from the token only when in proximity to a legitimate RFID scanner. In this way, user judgement is employed to prevent unauthorized data extraction from the RFID token.

Activation of the contact switch can be established with single or multiple human contact sensors, such that activating the token requires human contact or human interaction with at least one touch or contact switch.

[0048] The contact switch should be positioned on the RFID token such that it is clear to the user how to activate the contact switch, and, perhaps more importantly, where not to touch until the RFID token is required. This establishes a clear contact area on the contact switch such that a user can avoid activating the switch and thus prevent unauthorized transmission of data to an unauthorized scanner. In this way, the positioning of the contact switch minimizes unintended activation during regular handling of the RFID token. Visible, tactile or clear contact switches are preferable to prevent the accidental activation of the contact switch away from the range of the legitimate RF scanner.

[0049] The contact switch can be any switch which can be activated by touch or contact. It will be understood to the skilled person that the contact switch does not necessarily require direct pressure or direct contact (i.e. touch) with a human, but that it instead requires that a person interact with the contact switch in order to activate it. The contact switch can, for example, be a capacitive switch, or a mechanical switch that completes the RF retransmission circuit. Preferably, the switch is a capacitive switch, mechanical switch, or actuated switch. Non-limiting examples of a mechanical switches are a flip switch, a pressure-actuated button, other pressure switch, and a toggle switch. Other mechanical, electrical and/or electronic switches can also be used individually or in combination to achieve the human judgement or 'contact' element of the contact switch. Non-limiting examples of acceptable contact switches are magnetic switches, strain gauge switches, card orientation switches, and environmental sensing switches such as those that sense, for example, humidity, light level, or pressure. Other switches may also be used, such as magnetic or induction switches. Alternatively, or in addition, the contact switch can be an electronic switch such as, for example, a temperature-actuated switch, biometric switch, light-activated switch, capacitive switch optionally including a required signature pattern or trace input, or numerical or multi-button entry keypad switch, many of which are described in United States Patent No. 7,100,835, incorporated herein by reference.

[0050] One contact switch that may be used with the presently described security feature is a capacitive switch. The capacitive switch can have one or more capacitively sensitive regions. Various placements of a conductive contact switch are shown on an RFID card in Figures 3A - 3D. Specifically, a capacitive switch is shown with multiple contact regions on the front and/or back side of an RFID card, wherein the crosshatching in each figure shows the capacitively sensitive region. By having contacts on opposite sides of the card that must both be touched the accidental or inadvertent triggering of the card should be prevented. The contact areas can also be minimized to reduce the chance of accidental triggering. A capacitive sensor can also be combined with a secondary non-capacitive contact switch.

[0051] Alert Means

[0052] The RFID token can optionally include circuitry to indicate to alert a user of an unauthorized RFID scanner data extraction attempt. This alert element can alert the user to an in- progress RFID scanning or data theft attempt, or can track and record one or more attempted unauthorized scanning attempts for later view or notice by the user.

[0053] The alert means can be an indicator with an additional circuitry pathway whereby energizing the token with the touch switch in the open position triggers a "reset" pin on the touch switch such that the circuit cannot be closed to complete the token activation. A user alerting means or alert element can be added to the circuit pathway that is utilized when the security implementation is triggered. In this way, the reset pin is activated while the user is also alerted to the in-progress attack due to both components being part of the same circuit pathway. One example of an alert element is a light emitting diode (LED) indicator. Another alert means can be displayed on a screen on the token. Another example of an alert means is a vibration alert component like the vibrate function in a cellular phone.

[0054] An optional read-write memory can be further connected to the alert means or security switch to record information about the details of activation of the security switch. For example, the memory can record information when the alert signal has been triggered regarding the day, time, signal strength and/or signal frequency of the unauthorized scanner.

[0055] The alert means can also be configured to communicate the data between the

RFID token and a host computer or information management system by way of a transmitter. This transmitter can be wired or wireless. The transmitter can further communicate the details of the activation of the security switch on the RFID token, and can be intermittent or immediate, thus enabling rapid response to the presence of an unauthorized scanner. Such information can also be useful to retail establishments so the details of the presence of unauthorized scanners in an establishment can be tracked with the aim of reducing or preventing future attacks or possibly apprehending the unauthorized scanner or operator of the unauthorized scanner.

[0056] The RFID token can have any desired shape or configuration, and can optionally include a protective casing to protect the electronic circuitry. Non-limiting examples of token casings are sturdy films such as those used in credit, debit and security cards, and sturdy plastic cases such as those used in key or payment fobs. One example of the front and back faces of an RFID token fob with a capacitive contact switch is shown in Figures 4A. An example of an RDID token having a mechanical button with optional LED alert means is shown in Figures 4B and 4C, respectively. The RFID token is not restricted to a specific token type, and can be implemented on a variety of RFID tokens. The system can be implemented with any available active or passive RFID token and function without modification to how the token operates. Generally, the security switch will generally be configured to be connected between the RFID tag and the power supplying antenna.

[0057] The presently described system is implementable without requiring modifications to existing digital RFID communication protocols. RFID tokens configured for various radio frequencies transparently can be adapted to function with the additional security switch. In addition, the security switch is able to function on various types of RFID tokens configured for various communication and encryption protocols transparently.

[0058] Five exemplary embodiments of the presently described RFID token circuitry are shown in Figures 1 A to IE. The system may have one or multiple antennas for the collecting of RF for power and transceiver communication. As shown in Figure 1A, one configuration would be to have a capacitor so that the card energizes to a set power level then transmits or as Figure IB where no capacitor is used to "bank" a charge before the token transmits. The alert shown in Figure 1A is optional. Figure 1 A is an active RFID tag having a power source (battery). Figure IB is a passive RFID tag not having an internally connected power source. Figure 1C is one embodiment having a single antenna, wherein the antenna is used both to receive RF signal from a scanner and transmit signal through the same antenna. Figure ID is a passive RFID token without a capacitor. The circuitry pathway utilized when the security function is triggered can have an optional capacitor. The capacitor allows for a time delay to be established before the system resets back to ready. Figure IE, shows one embodiment wherein the capacitor adjacent the antenna is absent.

[0059] When the switch is in the open position, the resistive load on the circuit pathway builds such that it overcomes the resistor which allows the reset pin to be energized, keeping the switch in an open state until power is removed. In the presence of an

unauthorized scanner the reset pin is triggered, preventing the switch from moving to the closed state, thus preventing activation of the RFID token.

[0060] A power source to the RFID token can be passive, such that the current is induced by a receiving antenna on the token that drives the circuit, being activated by being scanned by an RFID scanner. Coupling with external RF scanners is achieved using antenna or transceiver structures.

[0061] A schematic of the process flow for the RFID token is shown in Figure 2. In operation, when a current is induced in the RFID token, (1) if the user is touching the sensor to activate the token, then power is provided to the token, which responds to the scan and retransmits the signal, and (2) if the user is not touching the sensor to activate the token, then power is provided to a reset pin and prevents the switch from connecting the power source to the token until the scanning ceases. In the second case when the security switch is activated in the absence of a user activating the contact switch, the power can also be shunted to an alert means such as an LED or other display on the contact switch that can causes the LED to light or alert means to be activated.

[0062] As shown in Figure 2, when the RFID token is exposed to an unauthorized scanner, in the presence of human contact or activation of the contact switch, the

unauthorized scanner is able to scan the token by energizing the RFID tag and having the RFID tag retransmit the data back to the scanner. When the contact switch is disabled, or there is no human contact with the RFID token, the unauthorized scanner attempts to energize the token, however the security switch shunts the signal away from the RFID tag and preferably to an alert means, such as an LED or screen, temporarily disabling the RFID token from being scanned. With activation of the alert means, the user of the RFID token can become instantly aware of an unauthorized scanner in proximity to the RFID token. After a set period of time, the disabling circuit in the security switch is discharged, and the RFID token then discharges so it can be scanned by an authorized scanner.

[0063] As shown in Figure 5, an unauthorized RF scanner can be placed or moved through an area where RFID tokens are used, such as at a point-of-sale. Each scanner has a radius or range area where communication can be established with RFID tokens.

Compromised RFID tokens within the range area of the scanner can be compromised by unauthorized scanning involving receiving and retransmission of RF signal from and to the unauthorized scanner. As the unauthorized RFID scanner moves through the crowd near the point-of-sale, the scanner transmits and receives RFID information from unprotected RFID tokens within the activation range. Customers standing in line to pay, without the presently described security features, may activate the contact switch on the RFID token unknowingly, enabling access of the data on the token to the unauthorized scanner.

[0064] RFID Sensor

[0065] Another application of the present RFID technology is in protecting users from unauthorized RF scanners in RF hotspots, such as near point-of-sale RF scanners or payment processing areas through the use of an RFID sensor.

[0066] In one example, a retail establishment using RF technology to process financial transactions can deploy one or more RFID sensors comprising an RFID tag and a security switch in combination with alert means such that the retail establishment will be alerted to the presence of an unauthorized scanner. This will enable the establishment to protect customers from rogue RF data theft attempts and deter the use of unauthorized scanners from stealing data from customers in the establishment.

[0067] Such RFID sensors can be deployed permanently in an area, such as fixed onto displays, near cash registers, or near entrances or exits to stores. The RFID sensor can also be deployed and configured to communicate back to a central location over various transmission mediums, or used in an ad-hoc fashion. For example, a single sensor can be walked around a retail establishment by an employee as part of regular loss prevention activities. The sensor can also be deployed transiently, such as on key tags or portable fobs or devices of employees such that an employee of the retail establishment can quickly be made aware of an unauthorized RF scanner.

[0068] The RFID sensor can be manufactured in isolation, or can be incorporated into a desktop or handheld device. The RFID token as well as the RFID sensor will preferably be encapsulated in a protective housing to protect the circuitry and electrical components, as previously discussed.

[0069] The present system is highly cost effective since it does not require retrofitting of existing RF scanning equipment and can be added to existing RFID token technology. In addition, implementing the additional automatic security switch does not require any costly processors or power-drawing electronics into the integrated circuitry of the RFID token, keeping the cost of an RFID token with the added security feature low.

[0070] All publications, patents and patent applications mentioned in this

Specification are indicative of the level of skill of those skilled in the art to which this invention pertains and are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

[0071] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A radio frequency identification (RFID) token comprising:

an RFID tag;

a security switch operatively connected to the RFID tag; and

a contact switch operatively connected to the security switch,

wherein exposure of the RFID tag to an unauthorized scanner in the absence of activation of the contact switch activates the security switch to prevent retransmission of an RFID signal from the token.

2. The RFID token of claim 1, wherein the security switch comprises a resistor.

3. The RFID token of claim 1, wherein the security switch comprises a reset pin.

4. The RFID token of any one of claims 1-3, further comprising alert means activated by the security switch.

5. The RFID token of claim 4, wherein the alert means comprises an LED, a vibrator, or a screen.

6. The RFID token of any one of claims 1-5, wherein the contact switch is a capacitive switch or a mechanical switch.

7. The RFID token of any one of claims 1-6, further comprising a battery.

8. The RFID token of any one of claims 1-6, wherein the RFID tag is passive.

9. The RFID token of any one of claims 1-8, wherein the RFID token is encapsulated in a protective housing.

10. A radio frequency identification (RFID) sensor comprising:

an RFID tag;

a security switch operatively connected to the RFID tag; and

alert means for indicating that the security switch has been activated by an unauthorized scanner,

wherein exposure of the RFID tag to an unauthorized scanner activates the security switch to prevent retransmission of an RFID signal from the device.

11. The RFID sensor of claim 10, further comprising a read- write memory for recording information about the details of activation of the security switch.

12. The RFID sensor of claim 11, wherein the details of activation of the security switch include the day, time, signal strength and/or signal frequency of the unauthorized scanner.

13. The RFID sensor of any one of claims 10-12, further comprising transmission means for transmitting a signal comprising the details of activation of the security switch.

14. The RFID sensor of any one of claims 10-13, wherein the alert means is an LED, a vibrator, or a screen.