Simple encryption method

Abstract

According to the simple encryption method provided by the invention, the encryption signal is superposed in the data line in the original communication bus, and the modulation-demodulation module is added in the original circuit, so that the encryption data can be sent based on the original chip without adding other chips; according to the method, encryption parameters of the encrypted signal are agreed based on an original communication bus protocol, an original circuit and a data communication mode do not need to be changed, and the transmission mode of the encrypted signal can be realized with relatively simple logic; according to the method, encrypted data can be sent at low cost, and meanwhile, the research and development period of equipment is effectively controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of data communication encryption, in particular to a simple encryption method. Background Art

[0002] In some smart devices such as printers and smart cars, the communication between the master chip and the slave chip is implemented based on SPI (Serial Peripheral Interface), IIC (Inter-Integrated Circuit) and 1-WIRE protocols. Usually, the communication between the master and the slave is encrypted based on software-based or hardware-based encryption methods in the existing technology. However, for some devices that need to strictly control costs, the performance of the original chip is relatively low. If encryption is implemented based on hardware chips, additional encryption chips need to be added, which will increase the overall R&D cost; if encryption is implemented based on software encryption algorithms, the storage and performance of the original chip cannot support the operation of the software algorithm, and the chip must be replaced. This causes the original system design to change synchronously with the chip, resulting in a longer R&D cycle for the device. Summary of the invention

[0003] In order to solve the problem that the encryption method in the prior art cannot be directly applied to the chips of some low-cost smart devices, the present invention provides a simple encryption method, which can utilize the original chip in the device to realize the transmission of encrypted data at a lower cost, while effectively controlling the research and development cycle of the device.

[0004] The technical solution of the present invention is as follows: a simple encryption method, characterized in that it comprises the following steps: S1: Add a group of modulation and demodulation modules to the master end and the slave end respectively, wherein the modulation and demodulation modules are used for analog signal modulation, demodulation and transmission and reception; S2: agreeing on encryption parameters for encryption signals between the master and the slave according to the protocol type of the communication bus between the master and the slave; The encryption parameters include: carrier wave, signal line for carrying and modulation parameters; the modulation parameters include: encryption frequency modulation or encryption amplitude modulation; S3: the master control end acts as a sending end to control the transmission of encrypted signals; The specific process of sending the encrypted signal includes the following steps: a1: The sending end passes the data to be encrypted through the modulation and demodulation module, and generates an encrypted signal based on the encryption parameters; a2: the transmitting end selects a signal interval in the carrying signal line to carry the encrypted signal, which is recorded as: encrypted signal carrying signal segment; a3: The transmitting end superimposes the encrypted signal on the frequency domain of the encrypted signal carrying signal segment based on the modulation and demodulation module, and sends it to the receiving end through the carrying signal line; S4: After the slave terminal demodulates the encrypted signal based on the modulation and demodulation module, the slave terminal performs corresponding processing according to the received signal; S5: the slave terminal sends back a feedback signal; S6: After the main control end receives the feedback signal sent by the sending end, a communication process is completed.

[0005] It is further characterized by: The modulation and demodulation modules of the master end and the slave end are always in working state, performing modulation and demodulation processing on all received signals; When the modulation and demodulation module modulates the encrypted signal, the voltage swing cannot exceed ±10% of the original circuit standard voltage; In step S2, the total length L of each data needs to be agreed upon between the master end and the slave end; The total length L is set to the longest length of data that needs to be encrypted between the master end and the slave end; The data sent by the sender can only be equal to the length of L. If the length does not meet L, it will be padded with 0; The number of signal segments carried by the encrypted signal is greater than or equal to 1; The protocol type of the communication bus includes: SPI, IIC or 1-WIRE; In step S2, when the protocol type of the communication bus between the master terminal and the slave terminal is not 1-WIRE, any data line in the protocol is selected as the carrying signal line; In step a2, when the protocol type of the communication bus between the master terminal and the slave terminal is 1-WIRE, the encrypted signal carrying signal segment can only be set in the high level signal segment; In step S5, the slave terminal sends back a feedback signal in the following ways: an encrypted signal sending way and a standard protocol response way.

[0006] The present invention provides a simple encryption method, which superimposes an encrypted signal in a data line in an original communication bus, and adds a modulation and demodulation module in the original circuit. It is not necessary to add other chips, and the encrypted data can be sent based on the original chip. In the method, encryption parameters of the encrypted signal are agreed upon based on the original communication bus protocol, and the original circuit and data communication method do not need to be changed. The encrypted signal sending method can be realized with relatively simple logic. The method realizes the sending of encrypted data at a relatively low cost, and effectively controls the research and development cycle of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic diagram of the structure of the encryption system of this application; Figure 2 This is an example of comparing frequency domain signals and time domain signals; Figure 3 This is an example of the 1-WIRE protocol read and write timing in the prior art; Figure 4 This is an example of encrypting an AM signal in a high-level signal segment; Figure 5 This is an example of encrypting FM signals in the high-level signal segment; Figure 6 It is the SPI communication signal in the prior art; Figure 7 Example 1 for encrypting and sending signals in SPI communication signals based on this method; Figure 8 This is Example 2 of encrypting and sending signals in SPI communication signals based on this method. DETAILED DESCRIPTION

[0008] In the present application method, encrypted data is sent in the modulated signal. The voltage and time of the conventional communication protocol show the characteristics of typical time domain signals, and of course some frequency domain information is also hidden, such as Figure 2 As shown. The so-called time domain signal is a signal that can be directly analyzed on the time axis, such as Figure 2 The 0 and 1 signals displayed by the time domain signal. The frequency domain signal is the frequency characteristics presented on the time axis, such as Figure 2 The intermediate frequency domain signal is a periodic waveform on the time axis, that is, a clock signal with a period of 10ns is converted into frequency information to 100MHz, and its frequency is fixed. 20us is 50MHZ, and information can be sent out periodically according to the different signal frequencies. This method adds modulation information to the conventional communication protocol, which can not only improve the communication efficiency per unit time, but also increase the communication concealment.

[0009] The present application includes a simple encryption method, which includes the following steps.

[0010] S1: Add a set of modulation and demodulation modules to the master end and the slave end respectively. The modulation and demodulation modules are used for analog signal modulation and demodulation and transceiver. The details are shown in 1. In this method, the superimposed signal can be achieved at the millivolt level through the modulation and demodulation module, and the normal communication is generally 3.3V.

[0011] S2: According to the protocol type of the communication bus between the master and the slave, the encryption parameters for the encrypted signal are agreed between the master and the slave. The encryption parameters include: carrier, signal line for carrying and modulation parameters; the modulation parameters include: encryption frequency modulation or encryption amplitude modulation.

[0012] The protocol type of the communication bus includes: SPI, IIC or 1-WIRE. When the protocol type of the communication bus between the master end and the slave end is not 1-WIRE, any data line in the protocol is selected as the signal line for piggybacking.

[0013] Among them, 1-WIRE protocol communication is achieved by one line to realize master-slave communication. Since there is only one line, the signal offline is responsible for both power supply and communication. The present invention only needs to ensure that the chip is powered normally (the 1-WIRE actual sequence is not adjusted) and add some interactions to achieve the purpose of simple encryption. The specific method is as follows.

[0014] like Figure 3 The write timing part in the conventional 1-WIRE protocol is the waveform of the binary digit 0 and digit 1 in the write process. It is mainly distinguished by changing the communication duty cycle. This part of the waveform is controlled by the master. The "0" SLOT indicates a write 0 operation, and the "1" SLOT indicates a master write 1 operation to the slave. In the figure, VPU refers to the power pull-up part of the master. The power part in the 1-WIRE protocol is provided by the pull-up resistor. Therefore, during the reading and writing process, the maximum pull-down time is generally 120us. When the signal is pulled low, the power is maintained by the capacitor integrated in the chip. The red line is controlled by the master, and the black line is controlled by the Vpu pull-up resistor. Figure 3 The middle read timing is the waveform of the slave chip responding to the binary digital 0 and 1. The red line part is controlled by the host, while the blue line is controlled by the slave when responding. The black line is pulled up by the pull-up resistor after the master and slave are released. The part where the lines intersect in the figure is time redundancy and can be adjusted freely.

[0015] During the 1-WIRE protocol communication process, it is entirely possible to send a set of modulation signals when the signal is pulled high. This type of modulation signal can be an amplitude modulation signal or a frequency modulation signal, as shown below Figure 4 It is the encryption of AM signal. Figure 5 It is FM signal encryption. Both encryption methods are to write 1 gap at the master end, and send AM signal at the same time during the period of level pull-up. After the demodulation module at the slave end demodulates the signal, it can selectively respond with standard protocol, or reply with the same method.

[0016] In multi-line protocols such as SPI, IIC or UART, this method can be implemented more efficiently because it is not restricted by the power supply environment. Figure 6 It includes: SPI communication, CS is the control enable pin, SCLK is the synchronous clock, MOSI / MISO is the data pin (can also be an independent line).

[0017] Figure 7In order to select the CS signal as the signal line for carrying, the modulated communication signal is superimposed on the SPI signal based on this method. In order to simplify the system structure and be more suitable for low-cost devices with limited performance chips, the superimposed signal in this method generally only selects one of the amplitude modulation or frequency modulation methods. The voltage of the SPI standard protocol is generally 3.3V or 5V, so the voltage of the modulated signal is preferably controlled within ±10%. The smaller the signal voltage, the smaller the signal, and the more difficult it is for the signal grabber to observe. Unlike traditional wireless communication methods, the wired communication scheme of this method requires that the time domain communication function is normal, and it is the main signal communication. Combined with the frequency domain communication method, some data information that needs to be hidden is "mixed" into the standard wired communication. Since it is a modulated signal, its modulation frequency can be set accordingly according to the cost requirements of the system. Of course, the higher the frequency, the shorter the signal, and the signal is more likely to be misjudged as a noise signal, thereby enhancing its communication security. Traditional wireless communication uses radio waves to communicate data on one or several channels using specific modulation rules, and its system complexity is much higher than that of wired communication.

[0018] Figure 8 This is an example of selecting the SPI clock signal SCLK as the signal line for the carrier. The transmitted digital signal is the same, and some information can be transmitted by changing the frequency of SCLK. Figure 8 This method is not recommended for practical applications because it is visible in the time domain and can be easily discovered by observers.

[0019] Other multi-line communication protocols also select the signal lines in a similar manner to SPI. When applying this method, the designer can choose to add a modulation module to any wired communication line to transmit and receive frequency domain information.

[0020] In order to reduce the complexity of the chip processing logic, in step S2, the total length L of each data needs to be agreed upon between the master and the slave; the total length L is set to the most common length of the data that needs to be encrypted between the master and the slave; the data sent by the sender can only be equal to L, and if the length L is not met, it is filled with 0. The specific data of L can be set according to actual needs. After agreeing on the signal length L, the encrypted signal can be sent based on this method, and it can be sent in whole or in segments, without the need for more complex judgment logic. Moreover, the specific value of the length L is not limited, ensuring that this method is more practical.

[0021] S3: The master end acts as the sending end to control the transmission of encrypted signals.

[0022] The specific process of sending encrypted signals includes the following steps: a1: The sender passes the data to be encrypted through the modem module and generates an encrypted signal based on the encryption parameters.

[0023] The modem modules of the master and slave terminals are always in working state, and perform real-time modem and demodulation processing on all received signals. When the modem module modulates the encrypted signal, the voltage swing cannot exceed ±10% of the original circuit standard voltage, ensuring that the transmission of the original signal is not affected.

[0024] a2: The transmitting end selects a signal interval in the carrying signal line to carry the encrypted signal, which is recorded as: encrypted signal carrying signal segment.

[0025] The number of signal segments carried by the encrypted signal is greater than or equal to 1, that is, the length of the signal segment carried by the encrypted signal can be greater than or equal to L, or less than L; because the total length L of the encrypted signal is agreed upon, when the modem module at the receiving end receives the encrypted signal in real time, it is determined to be a complete encrypted signal if the length L is met. Therefore, even if the encrypted signal is received in segments, it is considered a complete signal after the length L is met.

[0026] In step a2, when the protocol type of the communication bus between the master end and the slave end is 1-WIRE, the encryption signal carrying signal segment can only be set in the high level signal segment.

[0027] a3: The transmitter superimposes the encrypted signal on the frequency domain of the encrypted signal carrying signal segment based on the modulation and demodulation module, and sends it to the receiver through the carrying signal line.

[0028] S4: After the slave terminal demodulates the encrypted signal based on the modulation and demodulation module, the slave terminal performs corresponding processing according to the received signal.

[0029] S5: The slave sends back a feedback signal. The slave sends back a feedback signal in two ways: an encrypted signal sending method and a standard protocol response method.

[0030] S6: After the main control end receives the encrypted signal sent by the sending end, it completes the signal extraction based on the modulation and demodulation module, and completes a communication process.

[0031] After using the technical solution of the present invention, based on the protocol type of the communication bus between the master end and the slave end, a carrying signal line is selected, and a second signal is superimposed on the encrypted signal carrying signal segment of the carrying signal line, so that the communication efficiency per unit time is higher; the superimposed signal can be achieved at the millivolt level through the modulation and demodulation module, so that the signal can be hidden in the normal signal and is not easy to detect, thereby achieving a communication method with better encryption effect at a lower cost.

Claims

1. A simple encryption method, characterized in that: It includes the following steps: S1: Add a group of modulation and demodulation modules to the master end and the slave end respectively, wherein the modulation and demodulation modules are used for analog signal modulation, demodulation and transmission and reception; S2: agreeing on encryption parameters for encryption signals between the master and the slave according to the protocol type of the communication bus between the master and the slave; The encryption parameters include: carrier wave, signal line for carrying and modulation parameters; the modulation parameters include: encryption frequency modulation or encryption amplitude modulation; S3: the master control end acts as a sending end to control the transmission of encrypted signals; The specific process of sending the encrypted signal includes the following steps: a1: The sending end passes the data to be encrypted through the modulation and demodulation module, and generates an encrypted signal based on the encryption parameters; a2: the transmitting end selects a signal interval in the carrying signal line to carry the encrypted signal, which is recorded as: encrypted signal carrying signal segment; a3: The transmitting end superimposes the encrypted signal on the frequency domain of the encrypted signal carrying signal segment based on the modulation and demodulation module, and sends it to the receiving end through the carrying signal line; S4: After the slave terminal demodulates the encrypted signal based on the modulation and demodulation module, the slave terminal performs corresponding processing according to the received signal; S5: the slave terminal sends back a feedback signal; S6: After the main control end receives the feedback signal sent by the sending end, a communication process is completed.

2. A simple encryption method according to claim 1, characterized in that: The modulation and demodulation modules of the master end and the slave end are always in working state, and perform modulation and demodulation processing on all received signals.

3. A simple encryption method according to claim 1, characterized in that: When the modulation and demodulation module modulates the encrypted signal, the voltage swing cannot exceed ±10% of the original circuit standard voltage.

4. A simple encryption method according to claim 1, characterized in that: In step S2, the total length L of each data needs to be agreed upon between the master end and the slave end; The total length L is set to the longest length of data that needs to be encrypted between the master end and the slave end; The data sent by the sender can only be equal to the length of L. If the length does not meet L, it will be padded with 0.

5. A simple encryption method according to claim 1, characterized in that: The number of signal segments carried by the encrypted signal is greater than or equal to 1.

6. A simple encryption method according to claim 1, characterized in that: The protocol type of the communication bus includes: SPI, IIC or 1-WIRE.

7. A simple encryption method according to claim 1, characterized in that: In step S2, when the protocol type of the communication bus between the master end and the slave end is not 1-WIRE, any data line in the protocol is selected as the carrying signal line.

8. A simple encryption method according to claim 1, characterized in that: In step a2, when the protocol type of the communication bus between the master end and the slave end is 1-WIRE, the encrypted signal carrying signal segment can only be set in the high level signal segment.

9. A simple encryption method according to claim 1, characterized in that: In step S5, the slave terminal sends back a feedback signal in the following ways: an encrypted signal sending way and a standard protocol response way.

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