System and method for managing communication between contactless devices

Abstract

Various embodiments of the present disclosure relate to systems and methods for managing communications between contactless devices. The present disclosure relates to a modified NFC frame used by a reader and a selected device during at least a portion of communication between the reader and the selected device. The reader and the selected device store a modification rule for modifying the frame. Devices that do not store these modification rules will discard the received modified frames.

Description

[0001] This application is a divisional application of the invention patent application with the filing date of February 17, 2022 (the earliest priority date: February 17, 2021), the Chinese national application number 202210144811.3, and the title "System and Method for Managing Communication between Contactless Devices". Technical Field

[0002] Embodiments of the present invention relate to the field of contactless communication, such as Near Field Communication (NFC), and more particularly to frames used during communication between contactless devices. Background Art

[0003] Near Field Communication (more well-known in the art as NFC (Near Field Communication)) is a wireless connection technology that allows short-range (e.g., 10 cm) communication between electronic devices, such as between contactless smart cards or tags or between a mobile device and a reader.

[0004] NFC technology is particularly suitable for connecting any type of user device and allows for fast and easy communication.

[0005] A contactless device is a device capable of exchanging information with a contactless reader via an antenna according to a contactless communication protocol.

[0006] An NFC device as a contactless device is a device compatible with NFC technology.

[0007] NFC technology is an open standard technology platform in ISO / IEC 18092, ISO / IEC 21481, NFC Forum, and EMVCo, but combines many existing standards, such as Type A and Type B protocols defined in ISO-14443, ISO-15693 (Type V), or FeliCA JIS X6319-4 (Type F), and these standards can be communication protocols that can be used for NFC technology.

[0008] Contactless technology can also be used for Radio Frequency Identification (RFID) devices compatible with ISO 15693 and ISO 18000-3.

[0009] When transmitting information between a reader and a device, the reader generates a magnetic field via its antenna, which is typically a sine wave (carrier wave) of 13.56 MHz in commonly used standards.

[0010] To transmit information from the reader to the device, the reader uses amplitude modulation of the carrier wave.

[0011] The device includes a processor configured to demodulate the received carrier wave to obtain the data transmitted from the reader.

[0012] For the transmission of information from the device to the reader, the reader generates a magnetic field (carrier wave) without modulation.

[0013] The device antenna then modulates the field generated by the reader according to the information to be transmitted. The frequency of this modulation corresponds to a sub-carrier of the carrier wave. The frequency of this sub-carrier depends on the communication protocol used and can be equal to 848 kHz, for example.

[0014] This modulation is performed by modifying the load of the terminals connected to the device antenna.

[0015] Thus, two operating modes are possible: passive mode or active mode.

[0016] In passive mode, the device inverse-modulates the wave from the reader to transmit information and, for the transmission of information, does not integrate a transmitter itself or a transmitter, such as a transmitter capable of generating its own magnetic field during broadcasting. Such a device without a transmitter is called a passive device, as opposed to an active device that includes a transmitter.

[0017] Typically, a passive device has no power supply as it uses the wave from the reader to power its integrated circuit.

[0018] In active operating mode, both the reader and the active device generate an electromagnetic field. Typically, this operating mode is used when the active device is equipped with a power supply, such as a battery.

[0019] Each of the NFC devices (reader and device) uses a modulation scheme to transmit data. Here, again, the modulation results in an effect similar to load modification and this is called active load modulation (ALM) communication.

[0020] Compared to the passive communication mode, depending on the protocol used, a larger operating distance of up to 20 cm can be achieved.

[0021] In addition, the use of active load modulation allows for the use of very small antennas.

[0022] If the signal strength generated by passive load modulation is not strong enough to be detected by the reader, ALM needs to be used. This occurs when the antenna of the device is small or located in a challenging environment.

[0023] Embodiments of the present invention are applicable to various contactless devices, passive devices or active devices.

[0024] As described above, NFC is a ubiquitous technology based on well-known standards in the industry. The NFC frames used during communication rely on formats that are clearly defined for each technology. Therefore, all devices supporting the technology will receive and decode individual frames.

[0025] The open nature of NFC is crucial for applications that require interoperability but have some drawbacks in deploying NFC in certain systems:

[0026] a) NFC communication can be easily eavesdropped on and parsed because the payload format is common knowledge;

[0027] b) NFC systems without a strong security mechanism are vulnerable to replay attacks;

[0028] c) Since NFC frames rely on formats that are clearly defined for each technology, all devices supporting the technology will receive and decode individual frames, but frames that may not be suitable for certain receivers or devices in the NFC system will result in the reception and processing of frames that will be discarded at the application layer later.

[0029] Regarding a) and b), existing solutions based on advanced encryption and session mechanisms are robust but also expensive.

[0030] Although such a high level of security may be required for some high-cost / risk systems, it may be unreasonable for NFC systems addressing low-cost applications (e.g., disposable accessories).

[0031] Regarding c), processing the received payload requires energy, which is obtained from the reader's RF carrier.

[0032] Even when the received frames are not intended for some tags, the presence and processing of multiple tags may have a negative impact on the reader's energy consumption and maximum communication distance.

[0033] Therefore, another solution for improving security and communication distance is needed, especially in the presence of multiple tags. Summary of the Invention

[0034] According to one embodiment, it is proposed to prevent replay attacks as much as possible.

[0035] According to one embodiment, it is also proposed to improve the communication range, especially in the presence of multiple tags.

[0036] According to one aspect, a method for managing communication between a first non-contact device and a second non-contact device is proposed.

[0037] The device exchanges frames during communication that have a frame format (or structure) compliant with a contactless communication standard and include a frame start field, a frame end field, a payload field, and an error check field calculated from the payload field in a manner compliant with the communication standard.

[0038] The method according to this aspect includes storing modification rules in both devices, and for at least a part of the communication (or for the entire communication): causing the first device to modify the content of at least one frame element of each frame of at least a part of the communication according to the modification rules, such that the modified content of the at least one frame element is different from the reference content of the at least one frame element compliant with the communication standard, where the at least one frame element includes the frame start field or the frame end field or the payload field or the error check field; causing the first device to send the modified frame to the second device; causing the second device to receive the modified frame and analyze the at least one modified frame element according to the modification rules; and if the second device recognizes the at least one modified frame element, causing the second device to continue the communication.

[0039] Thus, the method according to this aspect proposes to maintain the standardized frame format or structure of the frame (maintaining the same fields as those included in the standardized frame) but modify the content of, for example, at least one frame element (such as one or more fields), such as the frame start field, resulting in such modified frames being processed only by (a) specific NFC systems, i.e., including, for example, readers and tags, and all tags store the modification rules allowing the modification of the content, while standard NFC devices should, for example, ignore these modified frames.

[0040] Attacks using off-the-shelf tools can be prevented, and eavesdropping can be weakened using basic tools because these tools support limited NFC technologies and standardized frames.

[0041] The complexity during tag manipulation increases because default reader tools may only support common NFC technologies (off-the-shelf tools, NFC-enabled smartphones, etc.), thus also helping to prevent attacks.

[0042] If individual systems use specific modification rules (one modification rule per system), replay attacks can also be prevented on a large scale, or if each system uses individual modification rules (one modification rule per tag), replay attacks between each tag can also be prevented.

[0043] The method according to this aspect thus introduces a certain level of prevention mechanism while keeping the system offline and without expensive and complex encryption and session mechanisms.

[0044] Additional frame acceptance / rejection (device addressing) is advantageously performed during actual reception. Thus, the application layer does not need to parse / digest the payload content.

[0045] The tag can reject unanticipated frames, thereby eliminating the need to harvest energy from the RF field at an early moment of communication, which is particularly advantageous when the content at the start of the frame has been modified.

[0046] In this way, the energy transmitted from the reader can be conserved to increase the communication range (when power is limited) when the addressed tag needs to digest and act.

[0047] As described above, according to an advantageous embodiment, at least one frame element includes a frame start field.

[0048] According to one embodiment, the modification rules include a set of functions, and modifying the content of at least one frame element includes applying at least one of these functions to the reference content of at least one frame element to obtain modified content that is different from the reference content.

[0049] When at least one frame element is an error check field, modifying the content of the error check field can include calculating the content of the error check field in a manner different from that indicated in the communication standard.

[0050] Both devices can apply the modification rules from the start of the communication.

[0051] As a variant, both devices can apply the modification rules from a defined moment of the communication.

[0052] The device can also apply the modification rules during a defined time period of the communication.

[0053] The modification rules can also include a set of different modification rules, and the method can thus include causing the two devices to apply the set of different modification rules at different moments of the communication.

[0054] According to another aspect, a system is proposed that at least includes a first non-contact device and a second non-contact device, which are configured to exchange frames having a frame format conforming to a non-contact communication standard and including a frame start field, a frame end field, a payload, and an error check field calculated from the payload in a manner conforming to the communication standard during non-contact communication.

[0055] The first device includes: a first storage medium for storing modification rules; a first processor configured to modify the content of at least one frame element of each frame of at least a part of the communication according to the modification rules such that the modified content of at least one frame element is different from the reference content of at least one frame element conforming to the communication standard, where at least one frame element includes a frame start field or a frame end field or a payload field or an error check field; and a transmitter configured to send the modified frames to the second device.

[0056] The second device includes a second storage medium for storing modification rules; a receiver configured to receive modified frames; and a second processor configured to analyze at least one modified frame element within each modified frame according to the modification rules and continue communication when at least one modified frame element is recognized.

[0057] According to one embodiment, at least one frame element includes a frame start field.

[0058] According to one embodiment, the modification rules include a set of functions, and the first processor of the first device is configured to modify the content of at least one frame element, including by applying at least one of these functions to the reference content of at least one frame element to obtain modified content different from the reference content.

[0059] According to one embodiment, at least one frame element is an error check field, and the first processor of the first device is configured to modify the content of the error check field by calculating it in a manner different from the manner indicated in the communication standard.

[0060] According to one embodiment, the first processor of the first device and the second processor of the second device are configured to apply the modification rules from the start of the communication.

[0061] According to one embodiment, the first processor of the first device and the second processor of the second device are configured to apply the modification rules from a defined moment of the communication.

[0062] According to one embodiment, the first processor of the first device and the second processor of the second device are configured to apply the modification rules during a defined time period of the communication.

[0063] According to one embodiment, the modification rules include a set of different modification rules, wherein the first processor of the first device and the second processor of the second device are configured to apply the set of different modification rules at different moments of the communication.

[0064] According to another aspect, a device, such as a contactless reader, is proposed as the first device belonging to the system defined above.

[0065] According to another aspect, a device, such as a transceiver, is proposed as the second device belonging to the system defined above.

[0066] According to another aspect, an object, such as an object belonging to the Internet of Things (IoT) field, is proposed, which includes an antenna and a device coupled to the antenna, such as the second device. Description of the Drawings

[0067] Other advantages and features of the present invention will appear in the following detailed description and the drawings, which are not restrictive, and in the drawings:

[0068] Figure 1 A system including several contactless devices is shown;

[0069] Figure 2 A first storage medium and a second storage medium storing modification rules are shown;

[0070] Figure 3 A standardized NFC frame of the prior art is shown;

[0071] Figure 4 An example modified frame that has been modified using the modification rules is shown;

[0072] Figure 5 A modification rule function is shown;

[0073] Figure 6 A modification rule function is shown;

[0074] Figure 7 A standardized NFC frame of the prior art is shown;

[0075] Figure 8 A modified frame with a modified SOF field is shown;

[0076] Figure 9 A standardized NFC frame of the prior art is shown;

[0077] Figure 10 A modified frame with a modified SOF field is shown;

[0078] Figure 11 Various ways of modifying the content of an error check field are shown;

[0079] Figure 12 A flowchart of communication management between a reader and a third device using the modified frame is shown;

[0080] Figure 13 A flowchart of communication management between a reader and a second device using the modified frame is shown;

[0081] Figure 14 A modified NFC frame used during the entire communication between a reader and a device is shown;

[0082] Figure 15 A standardized NFC frame for the first part of communication and a modified NFC frame for the latter part of communication are shown;

[0083] Figure 16Shows the standardized NFC frames used at the start and end of communication and the modified NFC frames used in between; and

[0084] Figure 17 Shows different modification rules for different parts of the communication. Detailed Description

[0085] In Figure 1 , the reference numeral SYS denotes a system including a number of contactless devices.

[0086] More precisely, an object such as a contactless reader RD includes a first contactless device DV1 coupled to a first antenna ANT1.

[0087] An object OBJ2 such as a transponder or tag includes a second contactless device DV2 coupled to a second antenna ANT2.

[0088] Another object OBJ3 such as another tag includes a third contactless device DV3 coupled to a third antenna ANT3.

[0089] In this example, the system SYS uses NFC technology for communication between the reader RD and the objects OBJ2 and OBJ3.

[0090] The first device DV1 includes a first processor PRM1 (e.g., an NFC controller), a first transmitter TRM1 specifically configured to perform modulation / demodulation of the RF carrier, and a first storage medium MM1, such as a non-transitory computer-readable memory.

[0091] The structure of the first transmitter TRM1 is conventional and is known per se.

[0092] The second device DV2 includes a second processor PRM2 (e.g., an NFC controller), a second transmitter TRM2 having a structure known per se and specifically configured to perform load modulation of the carrier, and a second storage medium MM2, such as a non-transitory computer-readable memory.

[0093] The third contactless device DV3 includes a third processor PRM3 (e.g., an NFC controller), a third transmitter TRM3 having a structure known per se and the same as that of the second processor PRM2, and a third storage medium MM3, such as a non-transitory computer-readable memory.

[0094] Of course, although Figure 1 shows only one device DV2 and one device DV3, the system SYS may include a number of devices DV2 and a number of devices DV3.

[0095] As Figure 2As shown, the first storage medium MM1 and the second storage medium MM2 store a modification rule MDFR, which is intended to be used to modify at least some frames exchanged during the communication between the reader RD and the object OBJ2 including the second contactless device DV2, as will be explained in more detail below.

[0096] However, the modification rule is not included in the third storage medium MM3 of the third device DV3.

[0097] Therefore, as will be explained in more detail later, the third device DV3 will not be able to process the modified frames sent by the reader RD.

[0098] Figure 3 A standardized frame STD that complies with one of the standards used within the NFC platform is schematically shown.

[0099] Such a standardized frame STDFR includes a frame start field SoF, a payload field PLD for the data sent or received within the frame, and an error check field EoD that includes two bytes CRC1 and CRC2 here. This error check field EoD allows checking for transmission errors and is calculated from the payload PLD in a manner compliant with the communication standard used.

[0100] The standardized frame STD also includes a frame end field EoF.

[0101] The third contactless device DV3 is intended to interpret and process such a standardized frame STDFR.

[0102] Figure 4 An example of a modified frame MFR is schematically shown, which has been modified from the standardized frame STDFR by using the modification rule MDFR.

[0103] As will be explained in more detail later, these modified frames MFR can be exchanged between the reader RD and the second device DVD from the start of the communication and throughout the communication or only during a part of the communication or only for specific commands.

[0104] Such a modified frame MFR has the same format or structure as one of the standardized frames STDFR. In other words, the format or structure of the modified frame MFR still includes a frame start field FLD1, a payload field PLD, an error check field FLD2, and a frame end field FLD3.

[0105] However, the content of at least one frame element of the frame is modified with respect to the reference content of the corresponding frame element of the standardized frame STDFR.

[0106] In Figure 4 the example shown, the content of all frame elements of the frame has been modified.

[0107] However, at least one frame element or some of the frame elements of a frame can be modified.

[0108] For example, only the frame start field FLD1 can be modified while keeping the other frame elements unmodified.

[0109] It is also possible to modify only the frame end field FLD3 or only the error check field FLD2.

[0110] As Figure 4 shown, the modification rules can include a set of functions f s , f d , f c and f e that are respectively applied to the reference content of the frame elements to obtain the modified content.

[0111] As Figure 5 shown, these functions f s , f d , f c and f e are selected such that the modified content obtained by applying these functions to the corresponding reference content of the frame elements is different from these corresponding reference contents.

[0112] For example, as Figure 6 illustrated in the figure, such a function fi applied to the content "a" can be equal to!a (! represents logical NOT).

[0113] As a variant, such a function fi applied to the content "a" can be the exclusive OR function of "a" and a constant C.

[0114] As a variant, the constant C can be replaced with different values K n respectively associated with different contents an.

[0115] Figure 8 Shows another possible way to modify the frame start field SoF of the standardized frame STDFR shown in Figure 7 .

[0116] More precisely, in this example of the standardized frame STDFR, the frame start field SoF includes an S bit before the first data byte of the payload PLD (note that in Figure 7 , P represents the parity bit).

[0117] In Figure 8 the modified frame MFR, the modified frame start field FLD1 can include n bits added after the S bit.

[0118] Figure 10 The figure illustrates a way to modify Figure 9Another example of a frame start field (or frame end field) of an example of a standardized frame STDFR as shown.

[0119] In this example, in compliance with standard ISO 15 693, modulation pulses are used to signal the start-of-frame field SoF of the standardized frame FTDFR.

[0120] In Figure 10 the modification rules may include a modified pattern of these modulation pulses to signal a modified start-of-frame field FLD1.

[0121] Regarding the check error field, although the check error field can be calculated in a manner defined in the communication standard and then a function can be applied to modify the obtained content of the check error field, it is also possible to modify the content of the error check field as Figure 11 shown by calculating the content of the error check field in a manner different from the way indicated in the communication standard.

[0122] More precisely, the error check field is typically calculated according to standard ISO13239 by using a polynomial and a standardized initial value STDIV.

[0123] This standardized initial value depends on the communication standard used.

[0124] It is also possible to invert or not invert the obtained result.

[0125] And, in order to modify the content of the check error field, the initial value can be modified and, for example, another initial value MIV can be used.

[0126] For example, four initial values MIV0, MIV1, MIV2, and MIV3 can be used that are different from the standardized initial value STDIV associated with the four illustrated standards, respectively.

[0127] Now referring more specifically to Figure 12 and the following to illustrate an example of communication management between a reader RD and a number of devices DV2 and DV3.

[0128] Figure 12 More specifically, communication management between a reader RD and a third device DV3 is shown, where the reader uses a modified frame.

[0129] In step ST120, device DV3 verifies the presence of modulation.

[0130] If modulation is present, then in step ST121, a third processor PRM3 of device DV3 analyzes the start-of-frame field SoF.

[0131] If it is assumed that the frame start field has been modified according to the modification rules, then the modified frame start field is not the expected frame start field SoF of device DV3.

[0132] Therefore, the frame is rejected and the communication is interrupted.

[0133] For example, if the frame start field is not modified in the modified frame and if it is assumed that the frame end field has been modified, then step ST122 is executed, including receiving start.

[0134] The incoming data is stored in device DV3 (step 123).

[0135] Then, in step ST124, the detection of the frame end field EoF is performed.

[0136] Since the frame end field has been modified, the modified frame end field is not the expected frame end field EoF, so device DV3 does not detect the frame end field EoF.

[0137] Therefore, the communication is interrupted again.

[0138] If it is assumed that in the modified frame, only the check error field has been modified, but neither the frame start field nor the frame end field has been modified, then in step ST124, the frame end field is detected, and in step ST125, the transmission error is checked.

[0139] Since the check error field does not correspond to the standardized check error field, in step ST126, the reception is not considered correct, and in step ST127, the communication is aborted.

[0140] Figure 13 The communication management using the modified frame between the reader RD and the second device DV2 is shown.

[0141] In Figure 13 it is assumed that the frame start field, the check error field, and the frame end field have been modified according to the modification rules.

[0142] In step ST130, the presence of modulation is verified.

[0143] If there is modulation, the frame start field FLD1 is analyzed, and if in step ST131 the field FLD1 is the expected field, then reception can start in step ST132.

[0144] If the modified field FLD1 is not the expected field, the frame is discarded and the communication is interrupted.

[0145] In step ST133, the incoming data is stored.

[0146] Also, in step ST134, the frame end field FLD3 is analyzed.

[0147] If this field does not correspond to the expected field considering the modification rules, the communication is interrupted again.

[0148] Otherwise, in step ST135, transmission errors are checked.

[0149] If the received check error field FLD2 corresponds to the expected check error field, in step ST136, the reception is considered correct, and in step ST137, the payload can be parsed.

[0150] If the reception is not considered correct, the communication is aborted.

[0151] In step ST138, if, for example, the received command is not the expected command, the communication is also aborted.

[0152] Otherwise, the process continues.

[0153] In other words, for a modified frame, if the expected SoF is not met (frame mismatch), the receiving process of the NFC system may discard the incoming reception.

[0154] In cases where an unexpected SoF is ignored, an unforeseen EoF may also cause the frame to be ignored.

[0155] In cases where frame errors are ignored (SoF and EoF), data integrity checks should trigger a transmission error due to a mismatched CRC field.

[0156] Thus, with a modified NFC frame, starting from the early moments of actual reception, only the (multiple) expected receivers (storing the modification rules) will be triggered, without relying on subsequent processing at the application layer.

[0157] Therefore, the use of modified frames allows a certain level of security to be given to some selected or desired devices (receivers), especially against replay attacks.

[0158] Furthermore, since devices that have not implemented the modification rules cannot interpret the received modified frames and thus interrupt the communication, the energy consumed by the reader is reduced and the communication range with the selected (desired) devices containing the modification rules is increased.

[0159] Now turning to Figure 14 it can be seen that the modified NFC frame MFR can be used throughout the entire communication between the reader and the device, from the start to the end of the communication.

[0160] As Figure 15As shown, the standardized NFC frame STDFR can also be used from the start of the communication up to time t1. Then, from t1 to the end of the communication, the modified NFC frame MFR is used.

[0161] As Figure 16 shown, the modified NFC frame MFR can also be used between time t1 and time t2 of the communication, while the standardized NFC frame STDFR is used during other periods of the communication.

[0162] As Figure 17 shown, the modification rule MDFR can also include a set of different modification rules MDFR1 - MDFR4.

[0163] And, as Figure 17 shown, for example, the modified frame MFR1 modified according to the first set of modification rules MDFR1 is used from the start of the communication until time t1.

[0164] The frame MFR2 modified according to the second set of modification rules MDFR2 will be used from t1 to t2.

[0165] The frame MFR3 modified according to the third set of modification rules MDFR3 will be used from t2 to t3, and the frame MFR4 modified according to the fourth set of modification rules MDFR4 will be used from t3 to the end of the communication.

[0166] These different times can be programmed and stored in the reader and the selected device DV2.

[0167] These times can be implemented by a counter that increments or decrements from the start of the communication, or can correspond to, for example, the start or end of a specific phase of the communication (tag activation, anti - collision, acquisition of the tag identifier (UID), etc.), or can correspond to the transmission / reception of a defined command. These examples are not restrictive.

[0168] As mentioned above, the reader and the selected device DV2 share the modification rule MFR, that is, they share the same configuration.

[0169] Several possibilities can be used to assign the modification rule or configuration to the reader and the corresponding selected device.

[0170] Thus, these modification rules can be assigned during the production of the reader and the selected device DV2.

[0171] Such an assignment can also be performed during production, but this can be changed manually.

[0172] For example, modification rules can be changed in the reader by a software / firmware update and can be changed in the selected device DV2 (e.g., a card) via a contact interface compliant with standard ISO7816.

[0173] Assignments can also be performed during production and the modification rule MFR can be changed when triggered at the backend.

[0174] More precisely, these modification rules can be changed in the reader by an automatic software / firmware update.

[0175] For example, the modification rules in the contactless device included in the card can be updated by the reader using dedicated RF commands, for example.

Claims

1. A method for non-contact communication through a first non-contact device, the method comprising: Exchanging frames with a second non-contact device, the frames having a frame format compliant with a non-contact communication standard and including a frame start field, a frame end field, a payload field, and an error check field calculated from the payload field according to the communication standard; Storing a modification rule; Modifying the content of at least one frame element of each frame of at least a part of the communication according to the modification rule such that the modified content of the at least one frame element is different from the reference content of the at least one frame element compliant with the communication standard, the at least one frame element including the frame start field, or the frame end field, or the payload field, or the error check field; And Sending the frame with the modified content to the second non-contact device.

2. The method according to claim 1, wherein the at least one frame element includes the frame start field.

3. The method according to claim 1, wherein the modification rule includes a set of functions, and modifying the content of the at least one frame element includes applying at least one of the functions to the reference content of the at least one frame element to obtain the modified content different from the reference content.

4. The method according to claim 1, wherein the at least one frame element is the error check field, and modifying the content of the error check field includes calculating the modified content of the error check field in a manner different from the calculation of the error check field in the communication standard.

5. The method according to claim 1, further comprising applying the modification rule from the start of the communication.

6. The method according to claim 1, further comprising applying the modification rule starting from a defined moment during the communication.

7. The method according to claim 1, further comprising applying the modification rule during a defined time period of the communication.

8. The method according to claim 1, wherein the modification rule includes a set of different modification rules, and the method further comprises applying different modification rules of the set at different times of the communication.

9. A method for non-contact communication through a second non-contact device, the method comprising: Exchanging frames with a first non-contact device, the frames having a frame format compliant with a non-contact communication standard and including a frame start field, a frame end field, a payload field, and an error check field calculated from the payload field according to the communication standard; Storing a modification rule; Receiving a modified frame from the first non-contact device, the content of at least one frame element of each frame of at least a part of the communication being modified according to the modification rule such that the modified content of the at least one frame element is different from the reference content of the at least one frame element compliant with the communication standard, the at least one frame element including the frame start field, or the frame end field, or the payload field, or the error check field; Analyze the at least one modified frame element within each modified frame according to the modification rule; and Continue the communication in response to identifying the at least one modified frame element.

10. The method according to claim 9, wherein the at least one frame element includes a frame start field.

11. The method according to claim 9, wherein the modification rule includes a set of functions, the modified content is different from the reference content, and the method further includes deriving the modified content of the at least one frame element from at least one of the functions applied to the reference content of the at least one frame element.

12. The method according to claim 9, wherein the at least one frame element is the error check field, and the method further includes calculating the modified content of the error check field in a manner different from the error check field calculation of the communication standard.

13. The method according to claim 9, further including applying the modification rule from the start of the communication.

14. The method according to claim 9, further including applying the modification rule from a defined moment during the communication.

15. The method according to claim 9, further including applying the modification rule during a defined time period of the communication.

16. The method according to claim 9, wherein the modification rule includes a set of different modification rules, and the method further includes applying the different modification rules of the set at different times during the communication.

17. A system for managing communication between a first non-contact device and a second non-contact device, the system comprising: The first non-contact device, including: A first storage medium configured to store a modification rule; A transmitter; A first processor coupled to the first storage medium and the transmitter; The second non-contact device, including: A second storage medium configured to store the modification rule; A receiver; A second processor coupled to the second storage medium and the receiver; Wherein the first non-contact device and the second non-contact device are configured to exchange frames during the communication, the frames having a frame format conforming to a non-contact communication standard and including a frame start field, a frame end field, a payload field, and an error check field calculated from the payload field according to the communication standard; Wherein the first non-contact device is further configured to: Modify the content of at least one frame element of each frame of at least a part of the communication according to the modification rule, such that the modified content of the at least one frame element is different from the reference content of the at least one frame element conforming to the communication standard, the at least one frame element including the frame start field, or the frame end field, or the payload field, or the error check field; and Send the frame having the modified content to the second non-contact device; and Wherein the second non-contact device is further configured to: Receive the frame having the modified content; Analyze the at least one modified frame element according to the modification rule; and Continue the communication in response to the at least one frame element being identified as modified by the second non-contact device.

18. The system according to claim 17, wherein the at least one frame element includes a frame start field.

19. The system according to claim 17, wherein the modification rule includes a set of functions, and modifying the content of the at least one frame element includes applying at least one of the functions to the reference content of the at least one frame element to obtain the modified content that is different from the reference content.

20. The system according to claim 17, wherein the at least one frame element is the error check field, and modifying the content of the error check field includes calculating the content of the error check field in a manner different from the communication standard.

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