System method and apparatus for secure transmission of confidential information

SYSTEM, METHOD AND APPARATUS FOR SECURE TRANSMISSION OF CONFIDENTIAL INFORMATION

This application relates to the assignee's United States Patent Application No. 09/022,289 "System, Method and Apparatus for Secure Transmission of Confidential Information, filed on February 11, 1998," See, pending assignee, U.S. Patent Application Serial No. 08/845,938, "Combined Mobile Telephone and Remote Control Terminal," which is a continuation-in-part of "and also filed April 29, 1997." included in the literature.

The present invention relates to a system, method and apparatus for establishing a secure wireless communication link between two devices that minimizes the risk of third party interception of sensitive information that may be exchanged during communication initiation.

Since Marconi demonstrated in 1897 the ability of radios to be in constant contact with ships sailing in the English Channel, the development of radio communications over the past century has been remarkable. Since Marconi's discovery, new wired and wireless communication methods, services and standards have been adopted by many people around the world. In particular, in the past decade or so, when the mobile wireless communication industry has grown more than tenfold, this development has accelerated and has been further accelerated by numerous technological advantages that have made portable wireless equipment smaller, cheaper and more reliable. Likewise, the potential growth of wireless telephony will continue over the next decade or so, as these wireless networks will interact with existing wireless networks and ultimately overtake existing wireless networks.

Cordless telephony has become part of the potential growth in cordless phones. Cordless telephony was originally intended to provide economical, unlimited range voice communication within residential areas using short radio links instead of cords between a telephone base and a handset. Although early cordless telephones had quality limitations, the introduction of improved cordless telephones to the market in the 1980s increased significantly. In particular, in Europe, more recent progress has been made in the area of use of cordless telephones outside of residential areas.

Another European, cordless telephone revolution is the Digital European Cordless Communication (DECT) standard, optimized for use within buildings. DECT controllers handoff active calls from one base unit to another as the user moves, and page or ring the handset as the user walks through areas covered by other base units. can overflow However, as is well known in the art, the range of cordless telephones is greatly limited compared to more directional cellular telephones. For example, for cellular telephones the range is 0.3-30 or more, and for cordless systems the range is less than 100 meters and typically up to several tens of meters.

More recently, the world of cellular and cordless telephones has begun to be covered by the introduction of cordless standards that are compatible with those of cordless telephones and their cousins, cellular. Thus, mobile cellular users can use their cellular telephones within a cordless telephone system, eliminating the need to purchase proprietary and typically incompatible cordless telephones. A private telephone system 10 having at least one private base station 12 and a plurality of cellular telephones 14 communicating with the base station is shown in FIG. In cordless mode, e.g., a cellular user at phone 14A can use another user, e.g., another cordless-mode cellular phone 14B or a cordless 16) can communicate.

One problem with the use of cellular telephones 14 within private telephone system 10 is security. As discussed, the earliest cordless phones, such as phone 16 in Figure 1, were standalone consumer products that did not require any interoperability specifications. In other words, each codeless telephone was attached to its own base station, and it was necessary to be compatible only with that base station. Problems such as charges, security, and privacy in these systems were solved by preventing the cordless telephone from operating with other base stations and limiting the transmission range of the cordless telephone. However, with the specification of the convergence and interoperability of cordless and cellular technologies, the inherent physical limitations of cordless systems no longer provide security. With cellular telephones 14 capable of transmitting signals over tens of kilometers, the use of telephones within private telephone system 10 increases a real security problem.

As is known in the art, cellular phone 14A may communicate via private base station 12 using an encoding key or other security protocol such as this, so that messages are encoded and more difficult to decrypt. Thus, even if the content of communications from a cellular user communicating with the private telephone system 10 may be sufficiently outside the outer reach of the system 10, the conversation or data being exchanged can be kept relatively confidential. However, another problem arises during communication initialization over the air interface, which must be done without encoding since no encoding keys are exchanged between the cellular users of the cellular terminal 14A. Thus, until encoding protocols are established, information, including keys, is broadcast over a wide range. Therefore, a third party can listen to such transmission before encoding to obtain sensitive information.

Various techniques can be employed to deter such eavesdropping. The first solution is to initiate private communication with the cellular telephone 14A electrically connected to the private base station using a wired connection during the initial information exchange. Thus, this solution requires the provision of an electrical interface between the two devices, limiting the freedom of manufacturers to design attractive terminals, since a standardized connector can increase the size and weight of the terminal. . In addition, such regulations may limit the development of the telephone 14, such as low voltage technology for energy saving and size reduction.

Another solution is to use Subscriber Identity Modules (SIMs) in the private base station 10 and each cellular terminal 14 so that the necessary identification information can be easily established so that the appropriate keys are applied without diverting the keys. will do In addition to the added component cost, the use of two SIMs in this manner adds to the management cost of the mobile network operator who must allocate unique SIM pairings between the private base station 20 and each cellular terminal 14 . Also, the SIM for the cellular terminal 14 can be inserted in the private base station 12 instead, making this solution more complicated.

A third solution is to use the advantages of the air interface, eg standardization. However, as discussed above, since radio waves propagate through walls and also over long distances, there is also a security risk that must be overcome.

In view of the shortcomings of the above-mentioned solutions, it is evident that a simple and secure security system and method are needed for establishing a communication link between a first device, such as a cellular telephone, and another device, such as a private base station.

Accordingly, it is an object of the present invention to provide a system, method and apparatus for establishing a simple secure communication link, whereby at least a portion of a transmission, in particular a transmission containing sensitive information, is transmitted explicitly for proper reception while minimizing the risk of eavesdropping. will provide

It is another object of the present invention to provide additional systems and methods for securely transmitting confidential or sensitive information establishing a connection between a first device and a second device communicating via a wireless link, eg a laptop computer and a peripheral device such as a printer. to provide tools and equipment.

Another object of the present invention is to provide a secure wireless transmission link between two predetermined devices in a workplace or home, for example, a computer that receives an Internet command and turns on a heater in an apartment. After establishing a secure link using the system, methods and devices of the present invention, the two devices can communicate over a short or long range wireless radio link without a dedicated cable or other physical interconnection.

The present invention relates to a system, method and apparatus for establishing a secure wireless wireless communication link between two devices that minimizes exposure of sensitive information by eavesdropping by third parties. For the exchange of sensitive information such as encoded information, a secure link is established by establishing an infrared link between two devices. Subsequent communications can then take advantage of encoding protection, establishing a secure wireless wireless communication link.

A more complete understanding and scope of the invention may be obtained from the accompanying drawings, which are briefly summarized below, from the detailed description of a preferred embodiment of the invention, and from the claims.

1 schematically illustrates a private telephone system comprising a cellular telephone and a private base station having a cordless telephone;

2 is a diagram illustrating a dual-mode radio frequency and infrared mobile station and a private base station according to the present invention;

Fig. 3 is a diagram illustrating various circuits used in the dual-mode device shown in Fig. 2;

4 is a diagram illustrating various devices communicating with each other using the principles of the present invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be fully described below with reference to the accompanying drawings in which preferred embodiments of the invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments given herein. Rather, the examples are provided in order to thoroughly describe the invention and to fully convey the scope of the invention to those skilled in the art.

The use of infrared (IR) transmission between various electronic devices, for example between a television and a remote controller, is known. For example, U.S. Patent Nos. 5,508,836, 5,588,009, 5,564,020, 5,617,236, and 5,446,783 each disclose a variety of IR electronic interconnects. U.S. Patent No. 5,636,264 describes an IR interface between a telephone handset and a computer. As described in more detail below, although these patent specifications describe the use of IR, these references do not discuss the above-mentioned security issues inherent in wireless communication, or We are not discussing a solution.

A dual-mode mobile station 20 in communication with a dual-mode private base station 21 is shown in FIG. As discussed, the mobile station 20 communicates with the private base station 21 via RF transmission, which has an effective range of several hundred meters, and a more limited 'cordless' communication mode, which has a much shorter coverage. As is known in the art, the RF transmission mode is through individual antennas 20A and 21A of the mobile station 20 and the private base station 21, and signals are transmitted and received in a conventional manner.

The transmit/receive interfaces 20B and 21B of the mobile station 20 and the private base station 21 are shown in FIG. Each interface includes a photodetector 22 for receiving IR signals and an IR signal emitter 23 for emitting these IR signals. The positions of the interfaces 20B and 21B on the body of the mobile station 20 and the private base station 21 are arbitrary, as long as the IR signals to and from the interfaces 20B and 21B are not blocked by the palm or finger of the phone user. In other words, as is known in the art, ergonomic considerations can handle the placement of interfaces.

With further reference to FIG. 2 , one of the practical uses of the dual-mode mobile station 20 is described. In particular, if the dual-mode mobile station 20 comes within range of the more limited private base station 21, e.g., in the same or a neighboring room, the subscriber may wish to switch control from the cellular provider to the private system. . For example, you may want to switch to the Public Switched Telephone Network (PSTN) through a private system to save money on lower landline phone rates. For example, via the PSTN 24, the mobile station 20 can communicate with a remote landline phone 25 and also via a base station transceiver system 27 (shown as a base station tower for simplicity) via a remote cellular phone ( 26) can communicate.

Referring to FIG. 3, a portion of the mobile station 20 (of FIG. 2), in particular an IR transmit/receive interface 20B, and various circuits within the mobile station 20 for processing IR signals are shown. The IR receiver or photodetector 30 receives IR signals from the private base station 21 and delivers these signals to the decoder 31, which converts the infrared information in the IR signal into electrical information, for example, a digital pulse. . The converted information is transmitted to the controller 32, which controls the flow of the electrical information (pulses). The signal conversion device 33 receives the electrical information flow, and groups these input pulses into a unit size (frame) according to a known signal format. As is well known in the art, the controller 32 may be a UART or other similar controller.

The converted input signal is sent to a processor 34, which executes the instructions given in the signal. It transmits the input signals to another phone, such as mobile station 14B (in FIG. 1), for example via an RF communication link. Similarly, in response to one or more commands, the processor 34 may transmit a message via IR communication by first sending a message to the signal converter 33 , which may transmit the message to the controller 32 . ) to the above electrical signal or pulse transmitted to the decoder (35). At the decoder the electrical pulses are converted into an IR radiation signal, which is transmitted by an IR transmitter 36, for example a light emitting diode, to emit an IR signal.

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

As discussed above, the effective range of the IR signal thus emitted is limited to several tens of meters. The effective range is further reduced by obstacles such as walls, floors and ceilings, as customers may feel in products such as television remotes. Thus, IR signals provide an excellent way for point-to-point conversations to exchange confidential information, effectively limiting communication wirelessly, even if temporary until a security protocol is securely established. Even if eavesdropping is possible, such range restrictions can prevent eavesdropping because other security measures, such as building controls, can be used to provide almost any level of eavesdropping protection.

Since various encoding methods can be used to conduct a radio conversation that is almost impossible for a decryptor to eavesdrop, wireless communication between users of the dual-mode phone 20 (of FIGS. 2 and 3) is switched to the RF communication mode. Decryption is prevented by exploiting the enhanced encoding security advantage. However, even with coding, wireless RF communication can be easily eavesdropped by a remote eavesdropper. Although the encoded data can prevent an eavesdropper from decrypting an intercepted encoded message, the caller and receiver must first establish a secure transmission through the exchange of encryption keys using unencrypted wireless communication. , which can be monitored by an eavesdropper and easily decrypt the appropriate keys to decrypt putatively secure-encoded transmissions.

The system, method and apparatus of the present invention provide an improved security scheme for preserving the confidentiality of wirelessly transmitted information by limiting the exposure of encoding keys and other confidential information through the use of IR transmission as described above. do.

In one embodiment of the present invention, when a subscriber of mobile station 20 is sufficiently close to the private telephone system, e.g., near a private base station 21, the subscriber causes mobile station 20 to transmit an IR signal via IR transmitter 36. Activate to release. Alternatively, the mobile station 20 may automatically activate the IR signaling capability prior to transmission and reception of any security-related data. In a preferred embodiment of the present invention, the mobile station initiates communication with a private base station 21, such as a cordless telephone base station, and after exchanging a code or other secure data such as the radio frequency normal for all non-secure transmissions. use Upon receipt of the above-mentioned secure data or protocols in transmission, the mobile station switches to IR signaling using the IR transmitter (36). It should be noted that, insofar as certain secure portions of the signals are transmitted via IR transmission, the RF-IR transition in the transmission may occur early, for example, during an initial communication attempt, or may occur later during transmission.

In any case, the private base station 21 detects the IR signal transmission from the mobile station 20 via the photodetector 30 in the base station 21, processes the input IR signal, and an IR response including the encoding key. respond with a signal It should be noted that one or more encoding keys may be inserted into the response signal by an encoding device 37 in communication with the processor 34 . When the mobile station 20 securely receives the encoding keys from the private base station 1 through IR transmission, the mobile station 20 can start/resume wireless RF communication encoded according to the encoding keys in the signal. As previously discussed, subscribers are then able to move more freely within the building while taking advantage of an inexpensive wired communication link over the PSTN 24 .

In another embodiment of the present invention, the private base station 21 periodically emits an IR signal, and the mobile station 20 can receive it if it is close enough. In practice, the private base station performs an IR poll to establish a spare IR link for the exchange of security information, such as the encoding keys described above. For example, upon detection (in the photodetector 30), the mobile station 20 (as in the private base station 21 in the previous embodiment) controls the subsequent RF transmission with the private base station 21, so that periodic or random It responds with an IR response signal, which may contain encoding keys providing a procedure for measuring security.

In another embodiment of the present invention, a subscriber of mobile station 20 or an administrator of a private telephone system may use a more secure IR communication link to transmit other non-initialization-related information. For example, if it is necessary to transmit sensitive information during RF communication, the mobile station 20 and the private base station 21 can switch to a more secret IR communication mode, and resume RF mode transmission after the sensitive information is transmitted. It should be noted that the mobile station 20 and the private base station 21 automatically return to the IR communication mode while within range of each other and can only switch when the IR transmission starts to deteriorate.

Although one preferred embodiment of the present invention uses the principles of the present invention in the context of a mobile phone, the scope of the present invention includes various dual-mode wireless interconnects that use infrared mode for security purposes, as given in the claims below. do.

4, assignee's United States Patent Application Serial No. 08/845,938, filed April 29, 1997, wherein a first device, such as a mobile phone, user's handset or computer, is incorporated by reference in its entirety. Another embodiment of the present invention is described that communicates with at least one of a number of other devices, such as those described in "Combined Mobile Telephone and Remote Control Terminal". It should be noted that although all the various devices shown in FIG. 4 may communicate with each other, certain pairs may not be available (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 send images to the printer 50 for printing. . However, the printer 50 is well able to send a print complete message (or out of paper or error message) to the PC 48 (with or without the security measure of instantaneous application).

Recent initiatives, such as the Bluetooth Mobile Communications Initiative, are accelerating the increasing interoperability of a variety of electrical, electronic and mechanical devices used in the workplace and at home. A number of different devices capable of using the above Bluetooth or other similar technologies are illustrated in FIG. 4, of which a home base station 40 is linked to a conventional public switched telephone network (PSTN) 42 (shown in FIG. 2 ). converts RF and infrared signals received from other devices, such as dual-mode telephones 26 and wireless headset/hands-free units 44 or other cordless devices 46 . A desktop or laptop PC 48 also has a printer/plotter/projector 50, a facsimile 52, a pager 54, a data organizer 56 or (organizer) 56) or other personal hand-held configurator devices, such as those that enable the downloading of sensitive information from or to the configurator and synchronization with data stored on the PC 48, with another PC 57 or with the electronic data terminal 58). It can interact with the scanner 60 , the microphone 62 , the PC card 64 , and a number of other peripherals denoted by reference numeral 66 . Of course, the principles of the present invention are also applicable to mobile station 26 and SIM card 26A, such as associated with the mobile station, or SIM card 67 separate from mobile station 26, as shown in FIG. can

In the home, many other household devices may be equipped with dual-mode functional devices such as those described herein. For example, PC 48 may intercommunicate with television 68 , radio 70 , stereo 72 or peripherals attached thereto, or VCR or other video player 74 (tape or disk). Other interconnected devices in the home include a lighting device (lamp) 76 , a dimmer switch 78 , a thermostat 80 controlling the heating/cooling of the home, and a gate such as a garage door. Intercommunicate with device 82 , refrigerator/freezer 84 , cooking device 85 (microwave, gas, etc.), washer/dryer 86 , answering machine 88 , and alarm device 90 . . Additional devices that may incorporate the inventive technology of the present invention include a vehicle warning device 92 (with vehicle locking feature), which must be located in close proximity, preferably within a line of sight, to operate in infrared mode, and a stationary type. Other external alarms that may be included are included.

Utilizing the principles of the present invention, via voice or handheld or wrist (watch) communication device 94, a user opens his garage door 82, exits and locks his vehicle, and his home alarm 90 A secure communication can be established by infrared or wireless link, allowing entry into his heated/cooled home by preceding remote command to the thermostat (relayed wirelessly by the home PC 48). can

Many wirelessly interconnected devices, such as those established under the Bluetooth initiative, are expensive, burdensome, and even though inexpensive, short-range wireless links can be used instead of dedicated cables, these communications can be easily eavesdropped by unauthorized users. Thus, it is imperative to secure the rf transmission, which can be in the range of several hundred meters or more, as it can be intercepted and decrypted to gain access to a user's personal area and property. The more secure initial infrared transmission of the present invention, which requires close, more in-line secure data exchange, provides the necessary level of protection required in open-to-tampering systems.

Currently, the frequency spectrum available for these private applications is more limited. For example, in the United States, if the transmit (TX) output level is low or spread is applied, the bands of 900 MHz, 2.4 GHz, and 5.5 GHz are currently licensed and can be used freely. The Bluetooth initiative will operate in the universally available 2.45 GHz Industrial, Scientific and Medical (ISM) 'free band', allowing international travelers to use Bluetooth-enabled equipment worldwide. It will be appreciated by those skilled in the art that spreading must be applied as a frequency hopping (FH) or direct-sequence (DS) spread spectrum to avoid interference. As described in the assignee's pending patent application "Method and Apparatus for Tracking a Mobil Phone", the 2.45 GHz ISM band can be used for a variety of devices and is also available from 2.4 GHz to 2.483 GHz. up to a range of bands. In an effort to avoid a sharp filter to meet the out-of-band emission need, as discussed in the above patent application that describes frequencies in a phone tracking system, the applied radio band moves away from the ISM band edge. location is preferred. It is desirable to avoid the known interference region from 2.435 GHz to 2.465 GHz in which microwave (microwave) ovens operate. Frequency Shift Keying (FSK) can be used to map user codes to rf carriers. In this FSK modulation technique, the bit representing '1' is mapped to the frequency rf + Df, and the bit representing '0' is mapped to the frequency rf - Df (or vice versa), where rf represents the carrier frequency and Df is the frequency deviation, which must be large enough to account for the frequency offset between the transmitter and receiver. For example, if an inaccurate frequency reference (with an accuracy of about 50 parts per million) is used, the worst-case frequency offset can reach 240 kHz. In order to receive a burst in this case, the frequency duration Df must be greater than 240 kHz.

Although current GSM technology is preferred, it should be noted that the principles of the present invention are applicable to time division multiple access (TDMA), personal digital cellular (PDC) and 3rd generation systems and equipment currently under development (future). Accordingly, the various frequencies used by these and other systems, such as the 800, 900, 1500, 1800, 1900, 2000, and 2100 MHz bands, may be used in the systems, methods, and apparatus of the present invention.

The above description is a preferred embodiment of implementing the present invention, and the scope of the present invention should not be limited to this description. The scope of the present invention is defined by the following claims.