Low-leakage telephone set secret communication circuit

Abstract

The invention discloses a low-leakage telephone set secret communication circuit which comprises a power supply circuit, an MCU circuit and an encryption circuit. The power supply circuit is connected with an external telephone line to take power and output power; the MCU circuit communicates with external communication equipment to realize telephone communication; and the encryption circuit is connected between the MCU circuit and the external communication equipment and is used for sending encrypted data, and after the external communication equipment is verified to be correct, the MCU circuit and the external communication equipment carry out telephone communication. Through the power supply circuit, external telephone line power taking is realized, and the power supply reliability of equipment is guaranteed; the encryption circuit performs data encryption verification before communication, so that information leakage is effectively prevented, and the communication confidentiality is improved; the three circuits work cooperatively, give consideration to the low leakage characteristic and the confidentiality requirement, provide safe and reliable confidentiality communication support for a telephone set, are suitable for scenes with high information security requirements, and promote improvement of practicability and security of confidentiality communication equipment.

Description

Technical Field

[0001] The present invention relates to a telephone, and more particularly to a low-emission telephone secure communication circuit. Background Art

[0002] Some organizations with high communication requirements require specialized low-emission phones. These devices utilize specialized design and technology to significantly reduce electromagnetic leakage emissions (TEMPEST). They are primarily used in high-security scenarios such as government networks, military, and finance to prevent unauthorized interception and reconstructing of conversations. Their core principle is to suppress electromagnetic radiation at the source by optimizing circuit layout, shielding materials, and filtering technologies. However, existing low-emission phones, when used with communication equipment, can compromise confidentiality by allowing calls to be made while other standard phones are connected. Summary of the Invention

[0003] In response to the shortcomings of the prior art, the present invention aims to provide a low-radiation telephone secure communication circuit that, when used in conjunction with dedicated communication equipment, automatically disables the telephone call function when another ordinary telephone is connected, greatly improving the line confidentiality function.

[0004] To achieve the above object, the present invention provides the following technical solution: a low-emission telephone secure communication circuit, comprising: A power supply circuit is connected to an external telephone line, and is used to take power from the external telephone line and then output power; The MCU circuit is connected to the external communication device for telephone communication with the external communication device; The encryption circuit is connected between the MCU circuit and the external communication device and is used to send encrypted data to the external communication device. After the external communication device receives the encrypted data and verifies that it is correct, the MCU circuit and the external communication device conduct telephone communication.

[0005] As a further improvement of the present invention, the encryption circuit includes: The encryption chip U4 has a voice signal sampling pin, a voice signal output pin, a coding receiving pin and a coding output pin. The coding receiving pin and the coding output pin are connected to the MCU circuit and the external communication device to encode and decode the communication data. The voice signal sampling pin and the voice signal output pin are connected to each other and then connected to the voice conversion circuit, and then connected to the external circuit line.

[0006] As a further improvement of the present invention, the voice conversion circuit includes: The analog switch U12D has a first end and a second end. The first end is connected to a resistor R103 and then connected to an external telephone line. A resistor R94 is connected between the first and second ends. The second end is connected to a capacitor C31 and a resistor R15 connected in series and then connected to a voice signal sampling pin. The other end of the resistor R15 opposite to the capacitor C31 is also connected to a resistor R9 and a capacitor C09 connected in parallel and then connected to the voice signal output pin.

[0007] As a further improvement of the present invention, a hands-free function circuit is further included. The hands-free function circuit is connected between the external hands-free receiver and the MCU circuit to open or close the hands-free call between the hands-free receiver and the MCU circuit.

[0008] As a further improvement of the present invention, the hands-free function circuit includes: The analog switch U16D has a first end and a second end. The first end is connected to the MCU circuit, a resistor R143 is connected between the first end and the second end, and the second end is connected to a resistor R38 and a capacitor C27 connected in series and then connected to an external hands-free receiver.

[0009] As a further improvement of the present invention, it also includes a handset circuit, which is connected between the external handle microphone, the external handle speaker and the encryption circuit and the MCU circuit to input the voice signal into the encryption circuit or receive the voice signal to play the voice content.

[0010] As a further improvement of the present invention, the handset circuit of the telephone receiver includes: An analog switch U12A, the analog switch U12A having a first end and a second end, the first end being connected to the encryption circuit, and the second end being connected to the external handle microphone; The analog switch U12B has a first end and a second end, the first end is connected to the MCU circuit, and the second end is connected to the external handle speaker.

[0011] Beneficial effects of the present invention: The present invention realizes the confidential communication function through the coordinated work of the power supply circuit, the MCU circuit and the encryption circuit. The encryption circuit encodes and decodes the communication data. When the communication equipment and the low-leakage confidential telephone are used at the same time, the low-leakage confidential telephone will respond to the encrypted data through the telephone line. After the communication equipment receives the encrypted data and verifies it successfully, the telephone function can be used normally, which effectively improves the security of communication. In addition, the setting of the hands-free function circuit and the answering machine handle circuit enriches the calling mode. The present invention overcomes the shortcomings of the prior art, can better meet the communication requirements of high-security demand scenarios such as party and government special networks, military, and finance, and improves the functionality and safety of low-leakage telephones. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A circuit diagram of an encryption circuit; Figure 2 This is the circuit diagram of the hands-free function circuit; Figure 3 This is the circuit diagram of the telephone handset circuit. DETAILED DESCRIPTION

[0013] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings.

[0014] Reference Figure 1 As shown, the secure communication circuit of the low-leakage telephone of this embodiment includes a power supply circuit, an MCU circuit and an encryption circuit. The power supply circuit is connected to the external telephone line, draws power from the line and outputs power; the MCU circuit is connected to the external communication device for communication to realize telephone communication; the encryption circuit is connected between the MCU circuit and the external communication device, sends encrypted data to the external communication device, and after the verification is successful, the MCU circuit establishes communication with the external communication device. In the process of using the communication circuit, the power supply circuit provides power to the entire system, and the encryption circuit encodes the communication data. Only the authorized device that passes the verification can decrypt and establish a connection, ensuring that the communication content is not illegally intercepted. Compared with the problem of reduced confidentiality performance caused by the existing low-leakage telephone communicating with non-encrypted devices in the background technology, this structure blocks the access of unauthorized devices from the source through the encrypted data verification mechanism, which significantly improves the confidentiality and security of communications.

[0015] Further, refer to Figure 1 As shown, the encryption circuit includes an encryption chip U4, which has a voice signal sampling pin, a voice signal output pin, a coding receiving pin and a coding output pin. The coding receiving pin and the coding output pin communicate with the MCU circuit and the external communication device to realize the encoding and decoding of the communication data; the voice signal sampling pin and the output pin are connected to the voice conversion circuit and then connected to the external telephone line. The encryption chip U4 samples and encodes the voice signal, transmits the encrypted digital signal to the external communication device through the coding output pin, and at the same time receives the encrypted signal of the external device and decodes it into a voice signal. The voice conversion circuit realizes the conversion between analog voice signal and digital encrypted signal, ensuring that the signal is transmitted in encrypted form in the telephone line. This design uses a dedicated encryption chip to achieve end-to-end data encryption. Compared with the unencrypted ordinary communication method in the background technology, it effectively suppresses electromagnetic leakage emission, prevents the call content from being illegally restored through electromagnetic radiation, and meets the confidentiality requirements of high-security scenarios.

[0016] Further, refer to Figure 1As shown, the voice conversion circuit includes an analog switch U12D. Its first end is connected to the external telephone line via resistor R103, with resistor R94 connected between the first and second ends. Its second end is connected in series with capacitor C31 and resistor R15, followed by a voice signal sampling pin. The other end of resistor R15 is connected in parallel with resistor R9 and capacitor C09, followed by a voice signal output pin. Analog switch U12D is turned on under the control of encryption chip U4. The analog voice signal from the external telephone line is current-limited by resistor R103 before passing through a filtering circuit consisting of resistor R94 and capacitor C31, converting it into a signal suitable for sampling by the encryption chip. The encrypted digital signal is filtered by resistor R15 and capacitor C09 before being fed back to the telephone line through analog switch U12D. This circuit, through a combination of resistors and capacitors, achieves signal filtering and impedance matching, reducing electromagnetic radiation leakage during signal transmission while ensuring the integrity of the voice signal and the accuracy of the encryption process, further enhancing the reliability of secure communications.

[0017] Further, refer to Figure 2 As shown, the circuit also includes a hands-free function circuit, connected between the external hands-free receiver and the MCU circuit, to control the hands-free function. The hands-free function circuit includes an analog switch U16D, whose first end is connected to the MCU circuit, a resistor R143 is connected between the first and second ends, and a second end is connected in series with a resistor R38 and a capacitor C27, followed by a connection to the external hands-free receiver. When a hands-free call is required, the MCU circuit controls analog switch U16D to conduct. The digital voice signal, after being current-limited by resistor R143, passes through a filter circuit consisting of resistor R38 and capacitor C27, converting it into an analog signal to drive the hands-free receiver. In the non-hands-free mode, analog switch U16D is disconnected, cutting off the signal path and preventing the risk of electromagnetic leakage in hands-free mode. This design uses an independent analog switch to control the hands-free signal path. Compared to the always-on hands-free circuit in the prior art, this design allows the hands-free function to be enabled on demand, reducing unnecessary electromagnetic radiation and further enhancing security.

[0018] Further, refer to Figure 3As shown, the circuit also includes a handset circuit that connects the external handset microphone and speaker to the encryption circuit and MCU circuit to implement voice signal input and output. The handset circuit includes analog switches U12A and U12B: The first end of analog switch U12A is connected to the encryption circuit, and the second end is connected to the external handset microphone, transmitting the voice signal from the handset microphone to the encryption circuit for encoding. The first end of analog switch U12B is connected to the MCU circuit, and the second end is connected to the external handset speaker, transmitting the decoded voice signal from the MCU circuit to the handset speaker for playback. When the handset is in use, analog switches U12A and U12B are closed, and the analog voice signal from the handset microphone is encoded by encryption chip U4 and transmitted to the external communication device. The encrypted signal from the external device is then decoded and played through the handset speaker. When the handset is not in use, the switch is open, terminating the signal path. This structure uses independent switches to control the handset signal path, preventing the handset microphone and speaker from becoming electromagnetic leakage channels when not in use, while ensuring encrypted signal transmission during handset calls, comprehensively improving the phone's confidentiality.

[0019] In summary, this solution, through the coordinated design of the power supply circuit, MCU circuit, encryption circuit, hands-free function circuit, and handset circuit, builds a fully encrypted, low-leakage communication system. Compared to existing technologies, it offers improved compatibility, allowing it to be used not only on dedicated communication devices but also on standard communication devices, while also avoiding the issue of compromised confidentiality associated with standard communication devices.

[0020] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A low-emission telephone secure communication circuit, characterized by: include: A power supply circuit is connected to an external telephone line, and is used to take power from the external telephone line and then output power; The MCU circuit is connected to the external communication device for telephone communication with the external communication device; The encryption circuit is connected between the MCU circuit and the external communication device and is used to send encrypted data to the external communication device. After the external communication device receives the encrypted data and verifies that it is correct, the MCU circuit and the external communication device conduct telephone communication.

2. The low-emission telephone secure communication circuit according to claim 1, characterized in that: The encryption circuit comprises: The encryption chip U4 has a voice signal sampling pin, a voice signal output pin, a coding receiving pin and a coding output pin. The coding receiving pin and the coding output pin are connected to the MCU circuit and the external communication device to encode and decode the communication data. The voice signal sampling pin and the voice signal output pin are connected to each other and then connected to the voice conversion circuit, and then connected to the external circuit line.

3. The low-radiation telephone secure communication circuit according to claim 2, characterized in that: The voice conversion circuit includes: The analog switch U12D has a first end and a second end. The first end is connected to a resistor R103 and then connected to an external telephone line. A resistor R94 is connected between the first and second ends. The second end is connected to a capacitor C31 and a resistor R15 connected in series and then connected to a voice signal sampling pin. The other end of the resistor R15 opposite to the capacitor C31 is also connected to a resistor R9 and a capacitor C09 connected in parallel and then connected to the voice signal output pin.

4. The low-radiation telephone secure communication circuit according to any one of claims 1 to 3, characterized in that: The invention also includes a hands-free function circuit, which is connected between an external hands-free receiver and an MCU circuit to open or close a hands-free call between the hands-free receiver and the MCU circuit.

5. The low-radiation telephone secure communication circuit according to claim 4, characterized in that: The hands-free function circuit includes: The analog switch U16D has a first end and a second end. The first end is connected to the MCU circuit, a resistor R143 is connected between the first end and the second end, and the second end is connected to a resistor R38 and a capacitor C27 connected in series and then connected to an external hands-free receiver.

6. The low-radiation telephone secure communication circuit according to any one of claims 1 to 3, characterized in that: It also includes a handset circuit, which is connected between the external handle microphone, the external handle speaker and the encryption circuit and the MCU circuit to input the voice signal into the encryption circuit or receive the voice signal to play the voice content.

7. The low-radiation telephone secure communication circuit according to claim 6, characterized in that: The handset circuit of the telephone receiver includes: An analog switch U12A, the analog switch U12A having a first end and a second end, the first end being connected to the encryption circuit, and the second end being connected to the external handle microphone; The analog switch U12B has a first end and a second end, the first end is connected to the MCU circuit, and the second end is connected to the external handle speaker.

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