Abstract:
A system for limiting access to confidential information including storage circuitry for storing the confidential information. An access enabling circuit allows access to the storage circuitry in response to a first level of an enabling signal. A processor generates the enabling signal for a predetermined amount of time in response to sensing of a change of a predetermined value that is produced in response to an act by a person responsible for the confidentiality of the confidential information. The enabling signal assumes a second level after the predetermined amount of time to block access to the storage circuitry.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to preventing unauthorized access to RFID (Radio Frequency Identification) documents such as passports, and more particularly to circuitry incorporated in passports and other confidential documents to prevent unauthorized RFID access to them unless certain conditions are met. 
         [0002]    The term RFID refers to the wireless use of radio-frequency electromagnetic fields to transfer data to automatically identify or track RFID “tags” or electronic labels on various objects. The RFID tags contain electronically stored information and may be powered up and read or interrogated at short distances by electromagnetic fields. Unlike a barcode, an RFID tag does not need to be within line of sight of an RFID reader, and may be embedded within an object to be accessed and interrogated. RFID typically uses an electronic chip which is affixed to the object to be accessed and typically contains identification information and other information which may be read, recorded, or rewritten. An RFID reader can provide the surge of power needed to “wake up” the access control circuitry in the electronic chip, read the passport data, and then go back to a “sleep state” or an “off state”. An RFID system uses RFID tags attached to or embedded within objects to be accessed/identified. RFID readers include transmitter-receivers, i.e., transceivers, for transmitting a signal to the tag and receiving and reading a response of the RFID chip. To start operation of a “passive” RFID chip, it must be powered by the signal transmitted by an RFID reader, wherein that transmitted signal has a power level roughly three times stronger than would be required only for RFID tag identification. 
         [0003]    Unfortunately, unauthorized access to typical RFID-based documents can be accomplished by means of any nearby RFID reader that is sufficiently close that its transmitted signal can “wake up” the RFID chip or tag of the document and thereby access data stored in it. Due to the nature of RFID reading, any accessing of the RFID chip requiring less than a half second can be transparent to the document user. A typical RFID tag requires 30-50 μW (microwatts) to operate. 
         [0004]    An RFID chip typically includes an antenna, a circuit for producing DC power from the RF signals transmitted by the RFID reader in order to power up the RFID chip, a transceiver for modulating and demodulating the RF signal, and integrated circuitry for storing and processing digital information. The tag information is stored in a non-volatile memory. The RFID tag may also include identification data storage circuitry. In operation, the RFID reader transmits an encoded RF signal to the RFID chip to interrogate it. The RFID chip receives and decodes the RF signal and then responds by transmitting stored identification information and possibly other information back to the RFID reader. 
         [0005]    RFID tags included in recent US passports typically store the same information that is printed within the passport and also store a digital picture of the passport owner. Unfortunately, the stored information is vulnerable to unauthorized “skimming” or eavesdropping of the RFID tag. In order to make it more difficult for nearby unauthorized RFID readers to “skim” information in a RFID passport tag while the passport is closed, a thin metal lining or shield has been included in or around the passports. However, this approach has been unsatisfactory in some cases because of its costs and also because of various user compliance problems. For example, some people either lose the passports or forget to replace the shields on the passports after removing them to allow them to be accessed by a RFID reader. In some cases the shields are so thin that they tear easily, and sometimes people simply fail to use them. Another method of preventing unauthorized reading of RFID tags in secure documents is by use of cryptography, which typically is complex and costly. Complex biometric passports (also known as digital passports) use contactless smart card technology including a microprocessor and antenna embedded in the cover or a center page of the passport, but these are costly and also unsatisfactory in some cases. If cryptography is utilized in every RFID-based passport or document, the cryptography needs to be complex and the associated calculations require a large amount of relatively expensive computing power. 
         [0006]    Thus, there is an unmet need for a convenient and inexpensive way to prevent unauthorized access to a RFID-based document or a passport by anyone who has a RFID reader that is sufficiently close to the document or passport to effectively scan its RFID code. 
         [0007]    There also is an unmet need for a convenient and inexpensive way to provide restricted access to a passport with RFID by anyone who has a RFID reader that is sufficiently close to the passport to scan its RFID code. 
       SUMMARY OF THE INVENTION 
       [0008]    It is an object of the invention to provide a convenient and inexpensive way to prevent unauthorized access to a passport with RFID by anyone who has a RFID reader that is sufficiently close to the passport to scan its RFID code. 
         [0009]    It is another object of the invention to provide a convenient and inexpensive way to provide restricted access to a passport with RFID by anyone who has a REID reader that is sufficiently close to the passport to scan its RFID code. 
         [0010]    Briefly described, and in accordance with one embodiment thereof, the invention provides a system ( 9 , 22 ) for limiting access to confidential information including storage circuitry ( 14 , 22 ) for storing the confidential information. An access enabling circuit ( 9 ) allows access to the storage circuitry ( 14 , 22 ) in response to a first level (“1”) of an enabling signal (ENABLE). A processor ( 22 ) generates the enabling signal (ENABLE) for a predetermined amount of time in response to sensing of a change of a predetermined value that is produced in response to an act by a person responsible for the confidentiality of the confidential information. The enabling signal (ENABLE) assumes a second level (“0”) after the predetermined amount of time to block access to the storage circuitry ( 14 , 22 ). 
         [0011]    In one embodiment, the invention provides a system ( 9 , 22 ) for limiting access to confidential information, including storage circuitry ( 14 , 22 ) for storing the confidential information; an access enabling circuit ( 9 ) for allowing access to the storage circuitry ( 14 , 22 ) in response to a first level (“1”) of an enabling signal (ENABLE); and a processor ( 22 ) for generating the enabling signal (ENABLE) for a predetermined amount of time in response to sensing of a change of a predetermined value that is produced in response to an act by a person responsible for the confidentiality of the confidential information, the enabling signal (ENABLE) assuming a second level (“0”) after the predetermined amount of time to block access to the storage circuitry ( 14 , 22 ). In one embodiment, the change of the predetermined value is produced in response to a physical act by the person responsible for the confidentiality of the confidential information. 
         [0012]    In one embodiment, the access enabling circuit ( 9 ) includes an RFID (Radio Frequency Identification) circuit ( 9 ) including a transceiver ( 10 ) and also includes an RFID tag ( 14 ) which is included in the storage circuitry ( 14 , 22 ). The RFID circuit ( 9 ) includes an enabling input for receiving the enabling signal. In one embodiment, the RFID circuit ( 9 ) is awakened and powered by energy received from a RFID reader ( 3 ). 
         [0013]    In one embodiment, the predetermined value is a capacitive value, the system including capacitance sensing (CapSense) circuitry ( 24 ) for sensing the capacitance value and determining an amount of change in the capacitive value, wherein the processor and the capacitance sensing circuitry ( 24 ) are part of a microcontroller ( 22 ). 
         [0014]    In one embodiment, the confidential information, the RFID circuit ( 9 ), and the microcontroller ( 22 ) are embedded in an RFID-based passport ( 5 ). 
         [0015]    In one embodiment, the RFID circuit ( 9 ) receives a wireless interrogation signal from an RFID reader ( 3 ) by means of an antenna ( 11 ), the antenna ( 11 ) being coupled to a rectifier circuit ( 17 ) which produces power to awaken and operate the microcontroller ( 22 ). 
         [0016]    In one embodiment, the system includes a battery ( 20 ) which provides power to operate the microcontroller ( 22 ). 
         [0017]    In one embodiment, at least part of the confidential information is contained in a secure package/container, wherein another part of the confidential information, the RFID circuit ( 9 ), and the microcontroller ( 22 ) are in the secure package/container ( 15 - 1 ) 
         [0018]    In one embodiment, the capacitive value is a capacitance associated with a conductive trace ( 16 - 1 ) which is embedded in a RFID passport ( 5 ) including the confidential information. 
         [0019]    In one embodiment, the microcontroller ( 22 ) operates to count a number of times the confidential information has been accessed to indicate whether the number of times indicates a security breach. 
         [0020]    In one embodiment, the confidential information is contained in an electronic document ( 14 , 22 ). The electronic document is stored in a wireless digital device ( 5 ) which communicates in accordance with a predetermined communication framework. 
         [0021]    In one embodiment, the invention provides a method for limiting wireless digital access to confidential information in a wireless digital device ( 5 ), the method including storing the confidential information in storage circuitry ( 14 , 22 ) in the wireless digital device ( 5 ); operating a processor ( 22 ) to generate an enabling signal (ENABLE) for a predetermined amount of time in response to sensing of a change of a predetermined value of a quantity that is produced in response to an act by a person responsible for the confidentiality of the confidential information, the enabling signal (ENABLE) having one level (“0”) after the predetermined amount of time to block access to the storage circuitry ( 14 , 22 ); and allowing wireless digital access to the storage circuitry ( 14 , 22 ) in response to another level (“1”) of the enable signal (ENABLE). 
         [0022]    In one embodiment, the wireless device is provided as a RFID (radio frequency identification) device ( 5 ). 
         [0023]    In one embodiment, the predetermined value is a capacitive value, the method including utilizing capacitance sensing circuitry ( 24 ) for sensing the capacitance value and determining an amount of change in the capacitive value, wherein the processor and the capacitance sensing circuitry ( 24 ) are part of a microcontroller ( 22 ). 
         [0024]    In one embodiment, the method includes embedding the confidential information, the RFID circuit ( 9 ), and the microcontroller ( 22 ) in an RFID-based passport ( 5 ). 
         [0025]    In one embodiment, the method includes storing the confidential information as an electronic document ( 14 , 22 ), and storing the electronic document in a wireless digital device ( 5 ) which communicates in accordance with a predetermined communication framework. 
         [0026]    In one embodiment, the invention includes a system for limiting wireless digital access to confidential information in a wireless digital device ( 5 ), including means ( 14 , 22 ) for storing the confidential information in the wireless digital device ( 5 ); processing means ( 22 ) for generating an enabling signal (ENABLE) for a predetermined amount of time in response to sensing of a change of a predetermined value of a quantity that is produced in response to an act by a person responsible for the confidentiality of the confidential information, the enabling signal (ENABLE) having one level (“0”) after the predetermined amount of time to block access to the storage circuitry ( 14 , 22 ); and means ( 9 ) for allowing wireless digital access to the storage circuitry ( 14 , 22 ) in response to another level (“1”) of the enable signal (ENABLE). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a block diagram of a system including a capacitive touch enabling system for preventing unauthorized scanning of an RFID passport. 
           [0028]      FIG. 2  a functional block diagram of the microcontroller in block  22  of  FIG. 1 . 
           [0029]      FIGS. 3A-D  are diagrams that show conductive traces of a touch capacitor which is embedded in a passport, a secure document, or its container. 
           [0030]      FIG. 4  is a diagram of a state machine that represents operation of the microcontroller in block  22  of  FIG. 1 . 
           [0031]      FIG. 5  is a flowchart illustrating a basic algorithm implemented by the microcontroller in block  22  of  FIG. 1 . 
           [0032]      FIG. 6  is a more detailed flowchart of the algorithm shown in  FIG. 5 . 
           [0033]      FIG. 7  is a flowchart that shows a variation of the algorithm shown in  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    Various embodiments of the invention protect information in a RFID-accessible document, e.g., a passport, by preventing it from being accessed or read by an RFID reader unless the document has first been touched, opened, or otherwise handled by the person in possession of the document in some way that “enables” it or “resets” it to allow information in the document to be accessed. The present invention thus prevents unauthorized access to the document, even if the RFID reader transmits sufficient power, by requiring the RFID circuitry embedded in the document to be “enabled” by the person in possession of the RFID document before it can be “powered up” in response to the signal transmitted by the RFID reader. For example, the RFID circuitry may be enabled if the person in possession of the passport or document touches a sense capacitor that is embedded in the document or physically opens the document or actuates a switch in or associated with the document. For example, there also may be a physical requirement for the person in possession of a passport to keep the passport open during scanning by the RFID reader to thereby indicate a need and intent by the passport holder to allow access to the contents of the RFID tag of the RFID circuitry. Such measures may effectively prevent unauthorized access to the contents of the RFID passport. 
         [0035]    Alternatively, a circuit somewhat analogous to RFID chip  9  but operative in accordance with a different suitable communications framework could be embedded in a cover of a package or case containing a device such as a smart phone or a computer such as a digital tablet so as to allow other kinds of wireless access such as Wi-Fi access, 4G access, or GPS communication with the device. 
         [0036]    In  FIG. 1 , a secure document identification system  1  includes a conventional RFID reader  3  which attempts to access information in an RFID passport  5  (or other secure document). Passport  5  includes a conventional RFID chip  9  embedded in a cover or disposed on a sheet of passport  5 . RFID chip  9  includes a transceiver  10 , an RFID tag or label  14 , and an antenna  11 . RFID reader  3  may be either authorized or unauthorized to access information from RFID tag  14  or any other part of passport  5 . An ultra-low-power microcontroller, which may be a commercially available Texas Instruments Wolverine ultra-low-power microcontroller, part number MSP430FR59xx (where the “xx” indicates the class of the microcontroller), is embedded in the cover or a sheet of passport  5 . Microcontroller  22  includes a peripheral capacitance bio-sensor or capsense circuit  24  which is capable of sensing changes in an external capacitance  30  embedded in or associated with the cover or pages of passport  5  caused by a person touching or opening passport  5 . 
         [0037]    Microcontroller  22  generates an enable signal “ENABLE” on conductor  26 , which is connected to an enable input of RFID chip  9  if a detected change in the above mentioned external capacitance exceeds a predetermined level and therefore indicates that the person possessing passport  5  wishes to allow the nearby RFID reader  3  to wirelessly enable RFID chip  9  and also allow information stored in chip  9  and in other parts of passport  5  to be accessed by RFID reader  3 . Microcontroller  22  may be powered by a voltage V DD  produced by a rectifier circuit  17 , the input of which is connected to transceiver antenna  11  in response to a sufficiently strong RF signal from the nearby RFID reader  3  and received by antenna  11 . Alternatively, microcontroller  22  may be powered by a lithium battery  20 . As indicated by dotted line  18 A, the output V DD  of rectifier  17  could also be utilized to charge lithium battery  20 . 
         [0038]    If RFID chip  9  is enabled, i.e., turned ON by a “high” level of the signal ENABLE, it can receive instructions and commands from RFID reader  3  and, in response to the instructions and/or commands, it can transmit data stored in RFID tag  14  and/or microcontroller  22  back to RFID reader  3 . RFID chip  9  can communicate with microcontroller  22  via a digital signal path  19 . When the ENABLE signal is “low” the entire RFID chip  9  is turned OFF and does not consume an unacceptably large amount of power. 
         [0039]    At this point, it will be convenient to briefly describe the structure and operation of the Texas instruments Wolverine MSP430FR59xx ultra-low-power microcontroller  22 . Referring to  FIG. 2 , which shows a functional block diagram of the MSP430FR59xx, microcontroller  22  includes a microprocessor unit  22 - 1 , a random access memory  22 - 2 , power management circuitry  22 - 3 , timer registers  22 - 4 , a multi-channel ADC (analog to digital converter)  22 - 5 , and a number of capacitive touch input/output ports  22 - 26  (included in block  24  in  FIG. 1 ) connected to corresponding external capacitive touch port conductors. (This is all in addition to the usual DMA controller, CPU, electrically erasable memory, bus control logic, clock generation circuitry, encryption/decryption circuitry etc., of a typical state-of-the-art integrated circuit microcontroller.) The fact that microcontroller  22  is a ultra-low-power microcontroller means that it can remain in a “hibernate” or extremely low power state or in an OFF state for a very long time interval and then “wake up”, perform various functions, and then go back into its sleep or hibernation state, and thereby use a very small amount of power over that long time interval. 
         [0040]    The very low power consumption of the MSP430FR59xx microcontroller  22  makes it suitable for long-term microcontroller implementations which are required to be intermittently operable over a very long amount of time while being powered only by a small battery or other low power source. In addition to its very low-power characteristics, the MSP430FR59xx microcontroller  22  also includes capacitive touch input/output (I/O) ports that may, for example, be connected to short copper traces or micro-wire traces that are connected to the capacitive I/O ports of MSP430FR59xx ultra-low-power microcontroller  22 . The MSP430FR59xx microcontroller  22  is able to detect capacitances and compute capacitance changes that occur in devices or circuitry connected to any of its I/O ports. For example, microcontroller  22  can sense the capacitance change that occurs when a human finger touches a copper trace embedded in an RFID passport. As another example, microcontroller  22  can sense the change in capacitance between separate copper traces that occur as a result of opening and/or closing a RFID passport and/or can recognize a sensed capacitance or capacitance change corresponding to an open state or a closed state of the RFID passport  5 . The MSP430FR59xx microcontroller  22  can accomplish this by “remembering” the previous capacitance value, comparing it with a corresponding present capacitance value, and computing the difference between them. 
         [0041]    The MSP430FR59xx microcontroller  22  can be “calibrated” based on various different “prototypes”. Example, if thin copper traces are embedded or formed on adjacent sheets of a RFID passport (or other secure RFID document) and the capacitance between the embedded copper traces is measured when the sheets are touching each other and also is measured when the sheets are not touching (while the passport is opened); that information can be used to calibrate microcontroller  22  and the passport in which the microcontroller  22  is embedded. The “calibrating” of microcontroller  22  includes calculating capacitances of the documents or materials used in the documents. 
         [0042]    A typical wakeup time for microcontroller  22  from a deep sleep state is from roughly 5 to 8 μs to as high as roughly 150 μs (microseconds). Note that the parameters of microcontroller  22  which are very important include first, the amount of power consumed during both the microcontroller&#39;s sleep mode and its active mode because they strongly affect battery life if a battery is used, and second, the amount of time required for microcontroller  22  to “wake up”, because this amount of time affects the response time of RFID passport  5  to an interrogation signal received from RFID reader  3 . (Note that the MSP430FR59xx microcontroller  22  has multiple selectable low-power states, all of which require different amounts of time for microcontroller  22  to wake up, so determining battery power usage versus microcontroller wakeup time is a trade-off that can be dealt with by selecting which low-power state to utilize. Microcontroller  22  can cycle between the various low-power states as it performs different functions.) 
         [0043]    In its active mode, microcontroller  22  requires approximately 100 μA (microamperes) of current per megahertz of operating speed. For 10 MHZ operation, microcontroller  22  requires 1 mA (milliamperes) of operating current for approximately 10 seconds. In its standby mode, in which microcontroller  22  typically spends nearly all of its time, its current consumption is only approximately 0.5 μA. For example, if RFID passport  5  is opened once per day, it is in its active mode for about 10 seconds every 24 hours, so its average current consumption is approximately 0.0227 mA per hour. In this example, a 1000 mA-hour battery source would have a lifetime of roughly 5 years, and a 2500 mA-hour battery would have a lifetime of roughly 12 years. 
         [0044]    The boot-up time from its off state for microcontroller  22  in this example is roughly one second, and its boot-up time is even less when it is waking up from a low power state. Therefore, the entire operation of waking up microcontroller  22  reading its capacitance sensing circuit  22 - 6 , checking the state of the document, and then enabling RFID chip  9  therein may be completed in less than roughly 5 milliseconds. 
         [0045]    The lifetime of a passport typically is 5 to 10 years or more. Therefore, if embedded microcontroller  22  is powered by a battery  20  it needs to consume only an extremely small amount of power when in its standby mode. The battery (or other power source) should not add significant bulk or cost to RFID passport  5 . In some cases, paper batteries or the like can be used to provide the power needed for an RFID document including embedded access-control circuitry of the kind described herein. (Each sheet of battery paper can generate approximately 2.4 volts with a power density of approximately 0.6 mA per square centimeter. For higher voltage requirements, battery paper sheets can be stacked. Battery paper operates from −100° Fahrenheit and is capable of delivering quick surges of current.) 
         [0046]    It should be understood that the term “document” as used herein is intended to encompass various items, including passports, paper documents, and company badges, which may have a lifetime of only one or two years. For example, a contractor working for a company may receive a secure RFID badge which needs to be replaced every year. In such a document or badge, a paper cell battery or the like might be adequate to power controller  22 . 
         [0047]      FIGS. 3A-D  are diagrams that show one or more elements of one or more touch capacitors (or alternatively, other types of switches and sensor elements, such as inductors) which can be “embedded” in a passport, a secure document, or its container. First,  FIG. 3A  illustrates the connection of multiple capacitive sensor elements  30 A embedded in one or more sheets  15  of a RFID-based passport  5 . Some of the capacitive sensor elements  30 A may be embedded in different sheets. All of the capacitive sensor elements  30 A are connected to corresponding ports of capacitive touch input/output circuitry  22 - 6  of microcontroller  22  ( FIG. 2 ). 
         [0048]      FIG. 3B  shows a capacitive sensor element  30 - 1  as a variable capacitance between conductive traces or micro-wires  16 - 1  and  16 - 2  in/on a sheet or cover  15 - 1  of RFID-based passport  5 . Capacitive sensor element  30 - 1  is illustrated as a variable capacitance, the capacitance of which may be influenced by the presence of a human finger or other at least somewhat conductive element being introduced into the region of the electrical field associated with conductive traces  16 - 1  and  16 - 2  (as subsequently explained with reference to  FIG. 3D ). If the finger simultaneously touches conductive traces  16 - 1  and  16 - 2 , it short-circuits traces  16 - 1  and  16 - 2  together so that in essence they function as an on-off switch. 
         [0049]      FIG. 3C  shows capacitive sensor element  30 - 1  as the variable capacitance between conductive traces or micro-wires  16 - 1  and  16 - 2  in the case in which conductive trace  16 - 1  is embedded in sheet or passport cover  15 - 1  of RFID-based passport  5  and conductive trace  16 - 2  is embedded in a different sheet  15 - 2  of passport  5 . Capacitive sensor element  30 - 2  is illustrated as a variable capacitance, the capacitance of which may be influenced by the presence of a human finger or other somewhat conductive element being introduced into the region of the electrical field associated with conductive traces  16 - 1  and  16 - 2 . 
         [0050]      FIG. 3D  shows a perspective view of passport sheet  15 - 1  in which a human finger  28  causes a variation in the capacitance between embedded conductive traces  16 - 1  and  16 - 2  by interrupting some of the electric field lines  29  between those conductive traces. If finger  28  actually touches both of conductive traces  16 - 1  and  16 - 2 , that short-circuits them together as if they were terminals of a mechanical switch. 
         [0051]    Conductive metal traces or micro-wires such as conductors  16 - 1  and  16 - 2  in  FIGS. 3B and 3C  are formed on or deposited on embedded in pages  15 - 1  and/or  15 - 2  of RFID passport  5 . These metal traces or micro-wires may be formed, for example, on one or two pages of passport  5 , as shown, and may be coupled to input/output terminals of capacitive touch I/O port  22 - 6  in  FIG. 2 . The capacitance between copper traces  16 - 1  and  16 - 2  in  FIG. 3B  varies as a human hand or finger touches them, and the capacitance between traces  16 - 1  and  16 - 2  in the example of  FIG. 3C  varies as RFID passport  5  is opened. Therefore the capacitance change between the present measured value of capacitance associated with one or both of the copper traces and a prior measured value of that same capacitance can be computed and compared to a threshold value that indicates whether the signal ENABLE applied by microcontroller  22  to the enable input RFID chip  9  of RFID passport  5  should be set to a “1” or “high” level to allow access by RFID reader  3  to the data on RFID tag  14 . 
         [0052]    Alternatively, variable capacitance  30 - 1  in  FIG. 3B  or variable capacitance  30 - 2  in  FIG. 3C  could be a manual switch that the person in possession or control of the RFID passport or other secure document could manually or even remotely actuate to enable wireless access to the secure passport or document. 
         [0053]    The state machine shown in  FIG. 4  defines the main action blocks or “states” of the secure document identification system shown in  FIG. 1 . The program executed by microcontroller  22  operates in accordance with 3 separate states. The first state is the “Waiting State” designated by reference numeral  34 , in which the program/algorithm waits for microcontroller  22  to “wake up” when it is in its “hibernation” state. The second state is the STATE_OPEN state designated by reference numeral  33 . The third stage is the STATE_CLOSED state designated by reference numeral  32 . Upon “waking up” when sufficient energy is received from a nearby RFID reader, if the condition for STATE_OPEN is met, the program/algorithm transitions to that state and performs a predetermined set of actions and then returns to the Waiting State  34 . However, if the condition for STATE_OPEN is not met, the program/algorithm instead enters the STATE_CLOSED condition designated by reference numeral  32  and can perform a set of actions if required and then returns to the Waiting State  34 . 
         [0054]    The flowchart of  FIG. 5  generally indicates how the microcontroller  22  wakes up, makes decisions and takes affirmative action so as to prevent unauthorized data access by RFID reader  3 . In  FIG. 5 , the program/algorithm executed by microcontroller  22  waits for sufficient energy to be received from a remote RFID reader as indicated in block  40 , and then wakes up microcontroller  22 , as indicated in block  42 . The program/algorithm then proceeds to decision block  44  to determine if the capacitive sensor  30  in  FIG. 1  and the capacitor input/output circuitry  24  in  FIGS. 1 and 2  have captured a valid input which indicates completion of the required authorization act by the person in possession or control of the RFID passport or other secure document. If the determination of decision block  44  is affirmative, the program operation proceeds to enable the RFID chip  9  in  FIG. 1 , as indicated in block  46  of  FIG. 5 . The program/algorithm then allows access to stored data in RFID tag  14  and/or microcontroller  22 , as indicated in block  48 . Upon completion of the data access operation, the program/algorithm returns to block  40 . If the determination of decision block  44  is negative, this means the external capacitance or sensors have not detected a valid input representing completion of the required action by the person in possession or control of the RFID passport. In this case, RFID chip  9  remains disabled, as indicated in block  50 , and access to the data in RFID passport  5  is blocked, as indicated in block  52 . The program/algorithm then returns to block  40 . 
         [0055]    In the case in which microcontroller  22  is powered by a battery, microcontroller  22  may be waiting in a low-power state because it already has a lithium battery providing power. Microcontroller  22  may be waiting in a loop for RFID energy to be detected. 
         [0056]    In the flowchart of  FIG. 6 , the RFID access control program executed by microcontroller  22  goes from entry label  54  to decision block  55  and determines if the RF enable signal ENABLE is at a high level. If this determination is negative, the RFID access control program goes to block  56  and ensures that ENABLE is at a low level so that RFID chip  9  is disabled and will not respond to an RF signal transmitted by RFID reader  3 . The RFID control program then returns to label  54  and repeats. 
         [0057]    If the determination of decision block  55  is affirmative, the program being executed by microcontroller  22  goes to block  58  and ensures that the signal ENABLE is at a high level and then measures the present (or very recent) touch capacitance value and then computes the present touch capacitance change by comparing the present touch capacitance with a prior value of the touch capacitance. The program then goes to decision block  59  and determines whether a touch or other required handling of the RFID passport or document by its owner has occurred. If that determination is affirmative, the program ensures that ENABLE is at a high level which enables RFID chip  9  as indicated in block  60 , and thereby temporarily allows RFID reader  3  access to data in the RFID tag  14  and possibly to other data in microcontroller  22 . The RFID access control program then returns to the entry point at label  54 . 
         [0058]    If the determination of decision block  59  is negative, the program goes to decision block  62  and determines whether the passport/document has been opened, and if this determination is negative, the RFID access control program returns to the entry point at label  54 . If the determination of decision block  62  is affirmative, the program returns to block  60  and sets ENABLE to a high level. 
         [0059]    Thus, a new additional security requirement is included along with any other existing security requirements that must be met before RFID reader  3  is allowed to access data in RFID passport  5 , wherein a physical touch or physical handling that generates an additional predetermined input to RFID passport  5  is required before it will enable RFID reader  3  to access anything in RFID passport  5 . The described embodiment of the invention prevents access to information in the RFID passport/document  5  by not allowing it to be accessed or read from an RFID-accessible document such as a passport without the document first being suitably touched/handled (and thereby “enabled”) by the person in possession of the RFID-based document. 
         [0060]    In one embodiment, the invention provides a RFID document/passport  5  including circuitry embedded therein which must sense the opening and/or closing or other physical handling of the RFID document before allowing access to the information stored therein. When the sense capacitor  30  embedded in passport  5  is touched by the person in possession of the RFID document, its capacitance changes. The capacitance sensing circuitry in microcontroller  22  senses the capacitance change. If the sensed capacitance change meets a predetermined threshold level, microcontroller  22  generates the signal ENABLE, which allows a sufficiently powerful interrogation signal transmitted by RFID reader  3  to “wake up” RFID chip  9  and allow information stored in RFID tag  14  to be accessed by RFID reader  3 . When RFID chip  9  “wakes up”, it can wake up microcontroller  22  if microcontroller  22  is powered by a battery  20 . If a rectifier  17  is provided, it can wake up microcontroller  22  and provide operating power to it. In one embodiment, the microcontroller  22  embedded in the passport or document  5  is powered wirelessly by the signal sent by RFID reader  3 . In another embodiment, the embedded microcontroller  22  is powered by a battery  20  embedded within the passport/document  5 . 
         [0061]    In one example, when microcontroller  22  is in its active mode, it requires about 100 microamperes of operating current per megahertz (MHZ). For 10 MHZ operation, the current requirement of microcontroller  22  in its active mode is approximately 1 milliampere for approximately 10 seconds, in order to respond to an “authorized” interrogation by RFID reader  3 . In its standby mode, the current requirement of microcontroller  22  is approximately 0.5 microamperes. If, for example, RFID passport  5  is opened once per day, microcontroller  22  operates in its active mode for about 10 seconds during that 24 hour interval. In that case, the cumulative current consumption/requirement of microcontroller  22  is 0.005 milliamperes+(2.5 milliamperes/0.17/24)=0.0227 milliamperes per hour. In that case, a 1000 mAH (milliampere-hours) battery can adequately power microcontroller  22  for roughly 5 years, and a 2500 mAH battery can adequately provide power to microcontroller  22  for up to roughly 12 years. (Typically, a battery (if used) only provides operating power to microcontroller  22  because RFID chip  9  typically receives all of its operating power wirelessly from RFID reader  3 .) 
         [0062]    The boot-up time for microcontroller  22  is roughly 1.5 milliseconds, and may be even less if microcontroller  22  is booted up from a low power or standby state. Thus, the entire operation of waking up microcontroller  22 , reading the touch capacitance, and computing the capacitance change, and then accordingly enabling or disabling RFID chip  9  can be completed in as little as 5 milliseconds or even less. 
         [0063]    Electronic documents and E-books are commonly loaded into an E-reader device such as a smart phone, tablet or laptop, and it may be desirable to avoid un-authorized non-physical interaction with such documents. The described access control could be utilized to help to further prevent unauthorized access to details of the documents or unauthorized loading of documents without the owner first performing a physical operation on a secure E-reader device. For example, an E-book or E-reader document may be sent from one person to another using a secure E-book or E-reader device wherein the information in the E-reader document has a predetermined lifetime that expires after a certain amount of time after which the document is automatically deleted. An unauthorized wireless transfer of such a document that could possibly occur, for example by using a Bluetooth data transfer mechanism, could be prevented by requiring a similar touching or handling of the smart phone, tablet, or laptop in order to enable a transfer of the E-book or E-reader document. 
         [0064]    In some cases it may be advantageous to know how many times a RFID-based document or passport has been accessed or opened. For example, if a top-secret document has been opened more than twice, that could suggest a possible security breach and information leak. Microcontroller  22  can be programmed to count the number of times RFID passport  5  (or other secure document) has been accessed or opened and provide that information to a user. In the flowchart of  FIG. 7  (which is the same as the flowchart of  FIG. 5  except for the addition of block  49 ), the secure identification program/algorithm goes from block  48  to block  49  and, in accordance with block  49 , increments a data access counter and then returns to block  40 . The person in possession or control of the RFID passport or other secure document can readily determine the number of times it has been accessed and then act accordingly. 
         [0065]    In some cases, the described electronic access control system may be utilized to prevent unauthorized access to a package or container which needs to be physically touched or otherwise physically handled or operated upon before RFID access to documents, passports, etc. or other wireless access utilizing a suitable digital communication framework can be achieved. 
         [0066]    Thus, the described embodiments of the invention prevent hackers or other unauthorized persons from stealing/accessing information in a RFID-based document or other secure document by simply being sufficiently close to the document to scan it with an RFID reader or the like. 
         [0067]    While the invention has been described with reference to several particular embodiments thereof, those skilled in the art will be able to make various modifications to the described embodiments of the invention without departing from its true spirit and scope. It is intended that all elements or steps which are insubstantially different from those recited in the claims but perform substantially the same functions, respectively, in substantially the same way to achieve the same result as what is claimed are within the scope of the invention. For example, changes in an inductance, rather than capacitance, located outside of the microcontroller chip could be measured. Furthermore, the predetermined change in value could be caused by multiple external conditions and is not limited to being caused by an act of a person. 
         [0068]    For example, there could be a requirement that two separate fingers touch two different touch spots of the document before access to an RFID passport or confidential document would be allowed or enabled. Also, the enable signal ENABLE in  FIG. 1  could actually be a “reset” signal which resets suitable circuitry in RFID chip  9  so as to prevent transceiver  10  from responding to a signal from RFID reader  3  unless microcontroller  22  determines that the person in possession of secure passport or document  5  has handled it in a required manner so as to allow it to respond to a signal from RFID reader  3 . Furthermore, the secure document or passport  5  could contain or respond to a physical switch that could be manually actuated in order to allow or enable RFID chip  9  to respond to a wireless request from RFID reader  3 . Also, the required act or acts by the person in possession or control of the RFID passport may require a sequence of steps to be performed by that person in order to authorize wireless access to the RFID passport.