System, method and apparatus for secure transmission of confidential information

System, method and device for secure transmission of confidential information

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation application of the assignee's U.S. Patent Application Serial No. 09/022289, the title of which is "System, Method and Apparatus for Secure Transmission of Confidential Information", dated February 1998 It was filed on 11th, and the co-pending US patent application with serial number 08/845938 and titled "Combined Mobile Phone and Remote Control Terminal" filed on April 29, 1997 by the assignee is incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a system, method, and device for establishing a secure wireless communication link between two devices, which can minimize the interception of sensitive information by third parties, such as those exchanged during the communication initialization process. The risk of sensitive information.

Background and purpose of the invention Since Guglielmo Marconi proved that radio can maintain uninterrupted contact with ships sailing in the English Channel in 1897, the development of wireless communication in the past century has been remarkable. Since Marconis discovery, people all over the world have adopted new wired and wireless communication methods, services and standards. This trend is accelerating, especially in the last ten years, countless technological advances have made portable radio equipment smaller, cheaper, and more reliable, and the mobile communication industry has therefore grown by several orders of magnitude. The exponential growth of mobile phones will continue in the next ten years, because this wireless network promotes each other with the existing wired network, and eventually replaces the wired network.

Cordless phones are also part of the exponential growth of wireless phones. The original purpose of the cordless phone was to provide economical cordless voice communication in the house, that is, to replace the wire between the landline and its mobile phone with a short wireless link. Although the quality of early cordless phones was quite reluctant, sales soared after the introduction of improved cordless phones in 1980. Especially in Europe, it has recently been developed to expand the use of cordless phones beyond residential buildings.

Another development direction of cordless phones in Europe is the Digital Enhanced Cordless Communication (DECT) standard, which is most suitable for use in buildings. When the user moves, the DECT controller can switch the ongoing call from one base station to another base station, and can page the mobile phone or make the mobile phone ring when the user passes through the area covered by different base stations. However, as everyone in the field knows, the range of cordless phones is quite limited compared with more general-purpose cellular phones, that is, the range of cellular phones is 0.3 to 30 kilometers or more. Cordless systems are within 100 meters, often only tens of meters.

Recently, with the introduction of a cordless standard compatible with Cellular Brothers, cellular and cordless phones have begun to move together. As a result, mobile cellular users can use their cellular phones within a cordless phone system, eliminating the need to specifically purchase cordless phones that are usually incompatible. Figure 1 shows a private telephone system, represented by a digital identification 10, which has at least one private base station 12 and a plurality of cellular phones 14 capable of communicating with each other. In the cordless mode, a cell phone user, such as the phone 14A, can communicate with another user in the private phone system 10, such as another cordless mode cell phone 14B or cordless phone 16, through the private base station 12 used as a relay station.

One problem with the use of the cellular telephone 14 in this dedicated telephone system 10 is security. As mentioned above, the cordless phone that makes the call, such as the phone 16 in Figure 1, is an independent consumer product and does not require any collaboration specifications. In other words, every cordless phone has its own base station, and it only needs to be compatible with its own base station. The billing, security and confidentiality in this system are guaranteed by preventing the cordless phone from being connected to any other base stations and limiting the transmission distance of the cordless phone. However, with the integration of cordless and cellular technologies and the use of collaborative specifications, the inherent physical defects of cordless systems make it no longer possible to guarantee safety. The cellular phone 14 can transmit signals several kilometers away. When such a phone is used in the dedicated telephone system 10, security is indeed a serious problem.

As everyone in the art knows, the cellular phone 14A can communicate through the private base station 12 with a key or other such security protocol, and the information in it is encrypted, making it more difficult to crack. Therefore, even if the communication of cellular users in the private telephone system 10 may extend beyond the range of the system 10, the conversation or the data exchanged is still relatively safe. However, another problem arises when the communication is initialized through the radio interface. Without encryption, such a problem will inevitably arise because cellular users, such as the cellular terminal 14A, do not exchange keys. Therefore, the information is broadcast in a wide range, including the key, until the encryption protocol is established. Therefore, a third party may listen to the signal transmitted before encryption to obtain sensitive information.

Various techniques can be used to deal with such eavesdropping. The first method is to use a wired connection in the initial information exchange process. In this way, there must be an electrical connection between the cellular phone 14A and the private base station to start the private communication. Therefore, this method requires the establishment of an electrical interface between these two components, which prevents manufacturers from designing a good terminal with their hands and feet, because standardized connectors will increase the size and weight of the terminal. In addition, doing so will limit further improvements to this type of phone 14, such as energy-saving and reduced-volume voltage reduction technology.

Another method is to use Subscriber Identity Module (SIM) in both the private base station 10 and the corresponding cellular terminal 14. In this method, the necessary identification information is already prepared, and the correct key can be used without transmitting them. In addition to increasing the component cost, the use of two SIMs in this way also increases the management cost of the mobile network operator. The operator must allocate a unique SIM pair for the private base station 20 and the corresponding cellular terminal 14. In addition, it is also possible to insert the SIM card of the cellular terminal 14 into the private base station 12, making this method more complicated.

The third method is to make full use of the radio interface, such as standardization. However, as mentioned above, because radio waves can penetrate walls and travel long distances, there are also safety issues in doing so, and these issues must be resolved.

Obviously, considering the shortcomings of the above methods, there is a need for a simple and safe system and method for establishing a communication link between a first device, such as a cellular phone, and another device, such as a dedicated base station. .

Therefore, an object of the present invention is to provide a system, method, and device for establishing such a simple and secure communication link, in which at least a part of information, especially information containing sensitive content, can be transmitted accurately and without error. And receiving, while minimizing the risk of being intercepted.

Another object of the present invention is to provide additional systems, methods and devices that can transmit confidential or sensitive information for use in the first and second devices communicating via radio interfaces, such as laptop computers and printers. Establish connections between peripherals.

Another object of the present invention is to provide a secure wireless transmission path between two devices, whether in the workplace or at home, such as a computer in a residence that accepts commands from the Internet to turn on heating. After a secure link is established by using the system, method and device of the present invention, the two devices can communicate through short-range or long-range wireless radio links without the need for dedicated cables or other physical connections.

Brief Description of the Invention The purpose of the present invention is to provide a system, method and device for establishing a secure wireless radio communication link between two devices, minimizing the risk of exposing sensitive information to a third party. This secure link is established by establishing an infrared link between the two devices to exchange sensitive information such as encrypted information. Subsequent communications will be encrypted and protected, thereby establishing a secure wireless radio communication link.

A more complete understanding of the present invention and its scope can be obtained by reading the following detailed description and claims of the preferred embodiments and referring to the accompanying drawings.

Brief Description of the Drawings Figure 1 is a schematic diagram of a private telephone system, which includes a private base station communicating with cellular and cordless phones; Figure 2 illustrates the dual-mode radio frequency and infrared mobile station and base station of the present invention; Figure 3 illustrates the Figure 2 shows the various circuits used in the dual-mode device; and Figure 4 illustrates various devices that communicate with each other using the principles of the present invention.

Preferred Embodiments Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings, which show preferred embodiments. However, the present invention can be implemented in many different forms, and should not be construed as being limited to these embodiments; on the contrary, the purpose of these embodiments is to make the description of the present invention more comprehensive and complete, so as to complete the content of the present invention. Introduce to those skilled in the art.

Transmitting infrared (IR) between various electronic devices, such as between a TV and a remote control, has long been well known. For example, US patents 5,508,836, 5,588,009, 5,564,020, 5,617,236, and 5,446,783 all introduce various IR electronic interconnections. Similarly, US Patent 5636264 introduces an IR interface between a telephone handset and a computer. Although these patent documents generally introduce the application of IR, they neither mention the inherent security problems of wireless communication mentioned above, nor the solution proposed by the present invention, which will be described in detail below.

In FIG. 2, a dual-mode mobile station 20 communicating with a dual-mode dedicated base station 21 is shown. As described above, the mobile station 20 communicates with the private base station 21 through an RF connection with an effective range of several hundred meters and a more limited and smaller range "cordless" communication mode. As everyone in the field understands, the RF transmission mode is carried out through the antennas 20A and 21A of the mobile station 20 and the private base station 21, and the signals therein are transmitted and received in a conventional manner.

Fig. 2 also shows the IR transceiver interfaces 20B and 21B of the mobile station 20 and the private base station 21, respectively. Each interface preferably includes a photodetector 22 for receiving IR signals and an IR signal transmitter 23 for emitting such IR signals. Obviously, the positions of the interfaces 20B and 21B on the mobile station 20 and the private base station 21 are arbitrary, as long as the IR signals between the interfaces 20B and 21B are not blocked, for example, beside the palm or fingers of the telephone user. In other words, how to install these interfaces mainly considers ergonomics, which is self-explanatory in the field.

With further reference to FIG. 2, the practical application of the dual-mode mobile station 20 will be described below. In particular, when the dual-mode mobile station 20 enters a more limited range of the private base station 21, such as in the same room or in an adjacent room, the user may wish to transfer the control right from the cellular provider to this private system, such as , Access to the public switched telephone network (PSTN) through a dedicated system, and save money with cheaper wired telephones. For example, through the PSTN 24, the mobile station 20 can communicate with a remote wired telephone 25 and a remote cellular phone 26 through a base station system 27 (for simplicity, represented by a base station tower).

Referring now to FIG. 3, there is shown (FIG. 2) a part of the mobile station 20, specifically the IR transceiver interface 20B and various circuits in the mobile station 20 for processing IR signals. The IR receiver or photodetector 30 receives IR signals, such as signals from the dedicated base station 21, and transmits these signals to the decoder 31, which converts the infrared information in the IR signal into electrical information, such as digital pulses. The converted information is then forwarded to the controller 32, which controls the flow of electrical information (pulses). The signal conversion device 33 receives the aforementioned electrical information stream, and organizes the incoming pulses into a unit size (frame) according to a known signal format. The controller 32 may be a UART or other similar controllers, as everyone knows in the art.

The incoming signal that has been transformed is transmitted to the processor 34, and the processor 34 executes the commands in the signal, for example, forwards the incoming signal to another telephone such as the mobile station 14B (in FIG. 1) through the RF communication link. . Similarly, the processor 34 may send a message through the IR communication link according to one or more commands. The message is first forwarded to the signal conversion device 33, and the signal conversion device 33 converts the structured message into the aforementioned The received electrical information or electrical pulses are then sent to the decoder 35 by the controller 32. In the decoder 35, the electrical pulse is converted into an IR radiation signal, which is emitted by an IR transmitter 36, such as a light emitting diode.

Of course, it should be understood that the circuit shown in FIG. 3 is preferably placed in the private base station 21, so that a wireless IR dialogue can be established with the mobile station 20.

As mentioned above, the effective range of the IR signal transmitted in this way is very limited, for example, about tens of meters. When touching walls, floors and ceilings, the effective range will be further reduced, which is the same as the situation encountered by users using products such as TV remote controls. In this way, IR signal provides a good way to exchange secret information in infrared mode. It effectively limits the communication signal within the range of point-to-point dialogue, although it is best to temporarily use it before the security protocol is safely established. a bit. Although it can still eavesdrop, it is limited by the range of action, because other security measures can be used at the same time to meet any level of protection requirements.

Because there are various encryption methods that can make the decryption machine almost lose its effect on the wireless conversation, in order to prevent the decryption, the wireless communication of the dual-mode phone 20 (Figure 2 and Figure 3) is better to switch to the RF communication mode, using encryption enhancement Security. However, despite the encryption, wireless RF communications are still easily intercepted by remote eavesdroppers. Although encrypted data can prevent an eavesdropper from decrypting the intercepted coded information, the calling party and the called party first exchange keys through unencrypted wireless communication to establish a secure transmission path. The eavesdropper can monitor all this. So it is easy to crack the relevant key, and then crack the encrypted communication signal that should be safe.

The system, method and device of the present invention provide an improved and more secure way to protect the confidentiality of wirelessly transmitted signals by preventing exposure of keys and other confidential information by using the aforementioned IR communication .

In one embodiment of the present invention, the user of the mobile station 20 is close enough to the private telephone system, for example, when close to the private base station 21, the mobile station transmits IR signals, for example, through an IR transmitter 36. Or when receiving and transmitting any data requiring safety, let the mobile station 20 automatically turn on the IR signal transmission mode. In an embodiment of the present invention, for example, when establishing communication with a private base station 21 such as a cordless telephone landline, and after exchanging encrypted data or other such data with security requirements, the mobile station adopts a traditional radio frequency method. To exchange all data that does not require security. In the process of information exchange, when encountering the aforementioned data or protocol that requires security, the mobile station 20 uses the IR transmitter 36 to switch to the aforementioned IR signal transmission mode. Obviously, the switch from RF to IR can be performed early in the exchange of signals, for example, in an attempt to establish a communication link, or later in the exchange process, as long as the encrypted signal is transmitted through IR.

In both cases, the private base station 21 will use the photodetector 30 in the base station 21 described above to detect the IR signal transmitted by the mobile station 20, process the received IR signal, and respond with an IR response signal. The response signal preferably includes a key. It should be understood that the encryption device 37 connected to the processor 34 can put one or more keys in the response signal. When the key is safely received from the private base station 21 through the IR signal, the mobile station 20 can safely start/restore the wireless RF communication. At this time, the wireless RF communication signal has been encrypted with the embedded key. So users can move freely throughout the building, and at the same time make full use of cheap wired communication links through the PSTN 24.

In another embodiment of the present invention, the private base station 21 periodically transmits an IR signal, and if it is close enough, the mobile station 20 will receive this signal. In fact, the private base station can use IR to interrogate, establish the initial IR connection, and exchange security information, just like the key described above. For example, when the (photodetector 30) detects a signal, the mobile station 20 (like the private base station 21 in the previous embodiment) responds with an IR response signal, which includes a key for subsequent use The RF signal is encrypted when communicating with the private base station 21 to provide a periodic or random encryption measure.

In another embodiment of the present invention, the user of the mobile station 20 or the administrator of the dedicated telephone system can use a more secure IR communication connection to transmit other non-initialized information. For example, if particularly sensitive information needs to be transmitted during the RF communication process, the mobile station 20 and the private base station 21 can switch to a more secure IR communication mode, and restore the RF mode after transmitting the sensitive information. It should also be known that the mobile station 20 and the private base station 21 can automatically switch to the IR communication mode when they are close to each other, and only switch back when the IR connection quality decreases.

Although one embodiment of the present invention is aimed at a mobile phone when adopting the principles of the present invention, it is obvious that the scope of the present invention, as stated in the claims, covers various dual modes that use infrared mode for security purposes. Wireless interconnection.

Referring now to FIG. 4, there is shown another embodiment of the present invention, in which a first device such as a mobile phone and a headset on the user's head or a computer communicate with one of a large number of other devices, such as this Those described in the assignees pending patent application, the title of which is "combined mobile phone and remote control terminal", US patent application number 08/845938, filed on April 29, 1997, here It is fully incorporated as a reference. Obviously, although the various devices shown in FIG. 4 are able to communicate with each other, some pairings may not be used (currently). For example, the printer 50 (receiving commands from a personal computer or PC 48) does not need to communicate with the TV 68, although the TV 68 can also send images to the printer 50 for printing. However, the printer 50 can (with or without the security measures in this application) send a print end message (or out of paper or error message) to the PC 48.

Recent protocols, such as the Bluetooth mobile communication protocol, will support more and more collaboration between various electrical, electronic and mechanical devices in the workplace and at home. Figure 4 shows many devices that can use Bluetooth or other similar technologies, including a home base station 40 connected to a common public switched telephone network (PSTN) 42, which converts from a dual-mode phone 26 (shown in Figure 2), and a wireless headset Wireless RF and infrared signals from other devices such as a microphone/hands-free unit 44 or other cordless device 46. The desktop or laptop PC 48 can also communicate with many accessory peripherals, such as printer/plotter/projector 50, fax machine 52, pager 54, data manager 56, or other such personal, handheld manager devices ( Used to exchange sensitive information with the manager 56 and to keep synchronization with the data in the PC 48, another PC 57 or the electronic data terminal 58), the scanner 60, the microphone 62, the PC card 64 and countless such peripherals, It is indicated by the number 66 in general. Of course, the principles of the present invention can also be applied to the mobile station 26 and the SIM card 26A, like the one used by the mobile station 26, or the SIM card 67 independent of the mobile station 26 as shown in FIG.

In the home, countless other household devices can be equipped with the dual mode function of the present invention. For example, the PC 48 can communicate with a TV 68, a radio 70, a stereo system 72 or peripherals connected to it or a VCR or other video player 74 (tape or disk). Other interconnected devices in the home include lamps (lights) 76, dimmer switches 78, thermostats 80 to control the heating/cooling of the residence, door devices 82 such as garage doors, refrigerators/freezers 84, kitchen utensils 85 (microwaves, gas, etc.) ), washer/dryer 86, telephone answering machine 88 and alarm device 90. Other devices that can use the technology of the present invention are car alarms 92 (with a car lock device). In order to work in infrared mode, they must be very close to it, preferably within the line of sight, and other devices that may be stationary. External alarm device.

Using the principles of the present invention, it is possible to communicate securely through infrared and wireless connections, enabling users to walk out and lock their car by inputting voice or keyboard commands from a handheld or wrist (watch) communication device generally represented by the number 94 , Turn off the alarm device 90 at home, and enter the home that has been heated/cooled by the remote control command sent to the thermostat 80 (relayed wirelessly by the home PC 48) in advance.

Obviously, although there are a large number of wirelessly interconnected devices with a composite Bluetooth protocol that can use low-cost short-distance radio links to replace the expensive and bulky dedicated cables that are now required, it is guaranteed that these distances can reach more than 100 meters for RF communication. Security is of utmost importance, because unauthorized users may easily eavesdrop, intercept and crack these communication signals, enter the users personal territory, and control the users personal belongings. This protocol, the more secure infrared method of the present invention, requires a very short distance and secure data exchange within the line of sight, which provides indispensable protection for these vulnerable systems.

Currently, the spectrum available for these dedicated devices is quite limited. For example, currently in the United States, the frequency bands at 900MHz, 2.4 GHz, and 5.7 GHz are not licensed and can be used freely, as long as the transmit (TX) power is very low or a spread spectrum method is used. The Bluetooth protocol plans to use the 2.45 GHz industrial, scientific and medical (ISM) "free frequency band" that can be used worldwide, enabling international travelers to use Bluetooth devices all over the world. For those skilled in the art, it is obvious that in the effort to avoid interference, spread spectrum technology, including frequency hopping (FH) or direct sequence (DS) spread spectrum, should be used. The 2.45 GHz ISM frequency band can be used for various devices, and its frequency band ranges from approximately 2.4 GHz to approximately 2.483 GHz. See the co-pending patent application "Method and Device for Tracking Mobile Phones" by the assignee. As stated in this patent application, in order to avoid the use of narrow-band filtering to filter out-of-band signals, the radio frequency band used should preferably be far away from the edge of the ISM band. Also avoid known interference zones, such as 2.435 GHz~2.465 used by microwave ovens GHz. The user code can be modulated onto the RF carrier with frequency shift keying (FSK). In this FSK modulation technology, the frequency RF+Df is used to represent "1", and RF-Df is used to represent "0" (or vice versa), where RF is the carrier frequency and Df is the frequency offset, the latter should be large enough , To deal with the frequency deviation between the transmitter and receiver. For example, if an inaccurate frequency reference (accuracy of about 50 ppm) is used, the worst frequency deviation can reach 240 kHz. In this case, in order to receive the pulse signal, the offset frequency Df should be greater than 240 kHz.

It should be understood that although the GSM technology is currently used, the principles of the present invention can also be applied to other time division multiple access (TDMA), personal digital cellular (PDC) and currently developed (and future) third-generation systems and equipment. Therefore, various frequencies used by these systems and other systems, such as 800, 900, 1500, 1800, 1900, 2000, and 2100 MHz frequency bands, can also be used in the system, method, and device of the present invention.

The preferred embodiments of the present invention have been described above, but the scope of the present invention is not necessarily limited to these descriptions. The scope of the present invention is illustrated by the following claims.