SK177197A3 - Radiocommunication equipment having a secure communication mode, and an extension unit formingpart of the equipment - Google Patents

Abstract

The equipment includes a secure coding extension unit (60) which is connected to a mobile telephone unit (10) and has a similar appearance to a mobile telephone. The mobile telephone is connected to a digital communication network. The extension unit has a microphone and a loudspeaker. Sounds from the microphone are passed to a vocoder and cypher coding system. The coded output is passed to the connected mobile telephone for secure communications, for example, via the GSM network.

Description

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Secure communication radio communication apparatus and extension unit as part of the apparatus.

Technical field

The invention relates to a radio communication mobile device which offers its user the possibility of confidential communication with other callers.

"Confidential Communication" here means communication having audio signals encrypted according to the encryption method and / or the encryption key only known to the participants or to the organization that groups them.

In particular, the invention aims to authorize such confidential communications in broad geographical areas.

BACKGROUND OF THE INVENTION

The current boom in public radiotelephony cellular networks offers attractive opportunities due to the existing number of stations providing very significant coverage of the area.

Some cellular networks allow encryption of audio communications. This is particularly the case for the European GSM system and the systems derived from it. However, the encryption performed typically ensures the confidentiality of the connection only in the phase interface environment. Even in the case of GSM communication between two mobile terminals, the audio signals are decrypted and transcoded (between 13 and 64 kbit / s) for connections between different infrastructure entities in the country. Communication security is then not perfect. In addition, the functions are encrypted under the control of the network operator and by no means to users, which is not a satisfactory situation to ensure confidentiality in the above sense.

It is an object of the present invention to provide a radio communication device suitable for confidential communication through an existing public mobile phone network infrastructure. It is also desirable to be able to use the device discreetly and in addition at an affordable price.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a radio communication apparatus comprising a radio terminal adapted to be connected to a public mobile phone network supporting audio and data channels, the radio terminal comprising a data interface for connecting a data input / output unit enabling communication on network data channels. According to the invention

It further comprises a data input / output unit and an expansion unit having an external appearance similar to a radio terminal and comprising at least a microphone, a handset, an audio digitizer and an encryption module. In secure communication mode, the audio digitizer generates a binary stream from the microphone-based signal, which the encryption module processes into data transmitted to the data interface for data channel transmission, and the data present on the data interface after receiving the data channel is decrypted by the encryption module. the audio digitizer decodes for the handset.

The invention also exploits the existence of a data channel in some radiotelephony networks. Confidential communications use these data channels more easily. The data thus exchanged represents audio signals and is encrypted and decrypted at each end of the communication. The third party supervising the communication path has no access to the audio signals without knowing the encoding method, encryption method and keys used for encryption.

The necessary functions of the secured communication method are grouped in an extension unit of an existing radio terminal. In order to assemble the kit for this particular application, it is thus possible to avoid the need to create a separate radio terminal compatible with the public network. As a result, the installation cost of the equipment is significantly reduced. The savings advantage is further enhanced by the use of a conventional radio terminal by benefiting from a large number of conventional radio mobiles, such as the development of cellular numerical networks such as GSM.

Another advantage of the device according to the invention is its confidentiality. The radio terminal used may be worn discreetly by the user and connected, for example, by a cable to an extension unit held by the user. The extension unit has an outward appearance than a radio communication terminal, so that the viewer feels that this is a normal radio connection and not a special, confidential connection.

Other particularities and advantages of the present invention will become apparent from the description of an exemplary particular embodiment and from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows the radio communication apparatus according to the invention in operation. Figures 2 and 3 are respective block diagrams of the extension unit and the radio terminal forming part of the device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 depicts a person using a radio communication device according to the invention, namely a radio terminal 10, an extension unit 60 and a connection cable 50. The user carries the assembly in a discreet manner by placing the terminal 10 in a garment pocket and holding the extension unit 60 in his hand; such as the sleeve of the garment and may not be visible.

The radio terminal 10, whose block diagram is shown in FIG. 3 is an ordinary terminal compatible with the public radio telephone network. Continuation of the description and explanation will consider the case of the GSM network without, however, limiting the invention to this case.

A detailed description of GSM is known to the person skilled in the art. Terminal 10 includes: microphone 12 and earpiece 14, GSM (RPE-LTP type) audio digitizer 16, modulator / demodulator 18 providing channel decoding encoding function, and AMTR (Multiple Time Distribution Approach) shaping under control of the control module 20 , a radio stage 22 performing an interface with the terminal antenna 24, a portable data reader 26 or a Subscriber Identity Module (STM) card where the subscriber subscription data is stored so that the control module 20 can perform the authentication and control tasks of the subpoena according to GSM standards, a keypad 28 for dialing subscriber numbers or calling other functions, a rechargeable battery 30 for powering various terminal modules.

In addition, the terminal 10 is provided with a number of interfaces grouped in a single connector 40 on which the connection cable 50 branches. These interfaces include: a data interface 32 for connecting an external data input / output unit. The interface 32 is coupled to a modulator / demodulator 18 for supplying data for transmission according to the radio network data channel and for transmitting the demodulated data upon reception on the radio network data channel towards the data input / output unit. In most known applications, the data input / output unit is typically a microcomputer or a fax: an antenna interface 34 for connecting an external antenna. Such an interface is often planned to utilize a terminal in an automobile so that the radio stage 22 can use the vehicle antenna; an audio interface 36 so that the audio digitizer 16 can receive its audio signals towards the voice microphone or external handset rather than the handset 14. Such an interface 36 is often planned to be connected to the free hand device at the terminals; a command interface 38 for connecting an external keyboard instead of a number dialing keypad 28 or other commands (most commonly, the external keyboard is a microcomputer or fax connected to the data interface 32).

An example of a GSM terminal 10 grouping the above interfaces in the same connector 40 is a MATRACOM 2050 terminal sold to the applicant.

The invention proposes to connect to such a radio terminal an extension unit 60 having the same external appearance as the radiotelephone terminal and equipped with a connector 90 which is an additional connector to the connector 40 for branching the connection cable 50.

The extension unit 60 includes a microphone 62 and a handset 64, a specific audio digitizer 66 for secure communication, and an encryption module 67. The encryption module 67 is connected to the data interface 32 of the terminal 10 via a connector 90 and a connection cable 50.

In secure communication mode, the expansion unit 60, more precisely, the encryption module 67, constitutes a data input / output unit connected to the interface 32 of the terminal 10. Audio signals received from the microphone 62 are encoded by the audio digitizer 66 then decrypted by the module 67 thereby producing data sent to the data interface 32. In another sense, the data received from the interface 32 is decrypted by the module 67, then decoded by the audio digitizer 66, wherein the audio signal so converted is transferred to the handset 64.

Thus, encrypted audio communications uses cellular network data channels. In the GSM network, data channels of up to 9600 bits / s are assumed (see GSM 02.02 recommendation), with a performance of at least sufficient for a large number of known audio digitizers. The user's counterparty may be equipped with a device of the same type or a still data transmission / reception device capable of decrypting the transmitted message.

The function of the expansion unit 60 is controlled by a control module 70 that cooperates with a portable media sensor 76. This data carrier is, for example, a chip card entrusted to the user, which may contain data of the same kind as the GSM SIM modules and which may have the same interface characteristics. However, this data relates to the user in relation to his organization or his correspondents and in any case not to the public network operator (the GSM SIM module must therefore be present in the sensor 28 of the GSM terminal 10). In particular, the control module 70 provides authentication and / or identification procedures between the user and its correspondent according to a predetermined protocol by comparing the corresponding data with the portable medium present in the sensor 76. The control module 70 defines, inter alia, the encryption key or keys that the module 67 She needs.

The extension unit 60 preferably comprises an antenna 74 which is connected to the antenna interface 34 via a connector 90 and a cable 50 for making an external antenna of the terminal 10.

The microphone 62 and the headphone 64 of the extension unit 60 may also be used in the audio interface 36 via the connector 90 and the interface cable 50 to form an external microphone and an external handset with the audio terminal 10 digitizer. security mode (via the audio digitizer 66, the encryption module 67, and the data channel), so it can also choose an unsecured communication mode (via the audio digitizer 16 and network audio channel).

The control module 70 is connected to another user interface formed by a keyboard 78 that allows the user to dial their correspondent number (wherein the keyboard 78 is connected as an external keyboard to the command interface 38 via the control module (70), select a communication mode (secure or unsecured) and optionally Expansion unit 60 may also include a notification screen (not shown).

Finally, the expansion unit 60 includes a rechargeable battery for powering its various components.

Claims (10)

PATENT CLAIMS A radio communication apparatus, comprising a radio terminal (10) adapted to be connected to a public network of mobile phones supporting audio and data channels, the radio terminal comprising a data interface (32) for connecting a data input / output unit enabling communication on network data channels, further comprising, as data input / output, an expansion unit (60) having an external appearance similar to a radio terminal and comprising at least a microphone (62), a handset (64), a sound digitizer (66) and an encryption module (67); in the secure communication mode, the audio digitizer generates a binary stream from the microphone-based signal, which the encryption module processes into data that it transmits to the data interface for data channel transmission, and the data present on the data interface upon receipt by the data channel is decrypted binary flow, who a digital audio decoder for the handset. Apparatus according to claim 1, characterized in that the radio terminal (10) comprises an antenna interface (34) for connecting an external antenna for transmitting and receiving radio wines by the terminal, and in that the extension unit (60) comprises an antenna (74) connected to Antenna interface as an external antenna. Apparatus according to claim 1 or 2, characterized in that the radio terminal (10) comprises an audio digitizer (16) adapted to the audio channel of the public network of mobile phones and an audio interface (36) for connection to the audio digitizer of the radio terminal of the external microphone and external the handset and by the microphone (62) and the handset (64) of the expansion unit (60) being connected to the audio interface to replace the external microphone and the external handset in unsecured communication mode. Apparatus according to claims 1 to 3, characterized in that the radio terminal (10) comprises a command interface (38) for connecting an external numeric keypad and that the expansion unit (60) comprises a keyboard (78) connected to the command interface as external keyboard. Apparatus according to claims 1 to 4, characterized in that the expansion unit comprises a control module (70) which controls at least a secure communication method and a sensor. -7 (76) a portable data carrier for exchanging authentication and / or identification data between the control module and the data carrier presented by the user An expansion unit for a radio terminal (10) adapted to communicate with a public mobile phone network supporting audio and data channels, the radio terminal comprising a data interface (32) for connecting a data input / output unit enabling communication over network data channels, an expansion unit (10). 60) characterized in that it is connectable to a radio terminal as a data input / output unit, having an external appearance similar to a radio terminal, comprising at least a microphone (62), a handset (64), a sound digitizer (66) and an encryption module (57) and that, in the security communication mode, the audio digitizer generates a binary stream from the microphone signal, which the encryption module processes into data and transmits them to the data interface for data channel transmission, and that data received by the data channel and submitted to the data interface are decrypted module to create a bin shrink flow, which vocoder decodes the handset. An extension unit according to claim 6 for a radio terminal (10) comprising an antenna interface (34) for connecting an external antenna for transmitting and receiving radio wines by a terminal, comprising an antenna (74) connectable to the antenna interface as an external antenna. An extension unit according to claim 6 or 7 for a radio terminal (10) comprising a sound digitizer (16) adapted to be connected to a public network of mobile telephones and an audio interface (36) to connect to the sound terminal of a radio terminal from an external microphone and external handset. characterized in that the microphone (62) and the handset (64) of the expansion unit (60) are connectable to the audio interface to serve the external microphone and external handset in unsecured communication mode. Expansion unit according to any of claims 6 to 8 for a radio terminal (10) comprising a command interface (38) for connecting an external keypad to a numeric dial, comprising a keyboard (78) connectable to the external keypad command interface. Expansion unit according to any one of claims 6 to 9, characterized in that: Comprising a control module (70) that controls at least a secure communication mode and a portable data carrier sensor (76) for exchanging authentication and / or identification data between the control module and the data carrier submitted to the sensor.