Visible light encryption method, decryption method, communication device and communication system

A communication device, comprising:

• a receiver, configured to receive a visible light signal from a transmit end and output a digital signal, wherein the visible light signal is encrypted at the transmit end by using a key;
• or a visible light signal is at least partially encrypted on the transmitting device by using a key that varies with a state of a state machine of the transmitting device;
• the decoder is configured to use keys corresponding to a current state of the state machine of the communication device and at least one state before and/or after the current state to decrypt the visible light signal;
• a decoder, configured to obtain the key, and decrypt the visible light signal according to the key, wherein the obtaining the key comprises:
• obtaining the key corresponding to a state of a state machine of a receive end;
• or, obtaining indication information according to the visible light signal and obtaining the key according to the indication information, wherein the indication information is used to obtain the key;
• the decoder specifically comprises:
• a pseudocode sequence indicator decomposing unit, configured to decompose the digital signal into a signal that comprises a pseudocode sequence indicator and a pseudocode signal;
• a pseudocode sequence querying unit, configured to query a pseudocode sequence corresponding to the pseudocode sequence indicator, wherein the pseudocode sequence is the key;
• and a convolutional decoder, configured to perform a logical operation on the pseudocode sequence and the pseudocode signal and output a logical operation result;
• wherein
• the decoder further comprises a device addressing code decomposing unit, configured to decompose the digital signal into a device addressing code and a first integrated signal;
• the pseudocode sequence indicator decomposing unit is configured to decompose the first integrated signal into the pseudocode sequence indicator and the pseudocode signal;
• and
• the pseudocode sequence querying unit is configured to determine legality of the pseudocode sequence indicator according to the device addressing code, and if the pseudocode sequence indicator is legal, query the pseudocode sequence corresponding to the pseudocode sequence indicator.

A visible light signal encryption method, comprising:

• encrypting data by using a key;
• and
• transmitting the encrypted data as a visible light signal, wherein the key varies with a state of a state machine of a transmit end, or the visible light signal carries indication information used to obtain the key;
• wherein in a case that the visible light signal carries the indication information, the encrypting data by using a key and transmitting the encrypted data as a visible light signal comprises:
• encoding a generated pseudocode sequence and the data to obtain a pseudocode signal, wherein the pseudocode sequence is the key;
• integrating a pseudocode sequence indicator corresponding to the pseudocode sequence into a header of the pseudocode signal to obtain an integrated signal that comprises the pseudocode sequence indicator and the pseudocode signal, specifically comprises:
• integrating the pseudocode sequence indicator corresponding to the pseudocode sequence into the header of the pseudocode signal to obtain a first integrated signal;
• integrating a device addressing code into a header of the first integrated signal to obtain a second integrated signal;
• and
• sending the integrated signal in a form of visible light.

A communication device, comprising:

• an encryption device, configured to encrypt data by using a key;
• and
• a transmitting unit, configured to transmit the encrypted data as a visible light signal, wherein the key varies with a state of a state machine of a transmit end, or the visible light signal carries indication information used to obtain the key;
• wherein
• the encryption device comprises:
• a pseudocode generator, configured to output a pseudocode sequence and a corresponding pseudocode sequence indicator;
• a convolutional encoder, configured to perform a logical operation on the pseudocode sequence and the data, and output a pseudocode signal;
• and a pseudocode sequence indicator integrating unit, configured to integrate the pseudocode sequence indicator into a header of the pseudocode signal, and output an integrated signal that comprises the pseudocode sequence indicator and the pseudocode signal, wherein the pseudocode sequence is the key, and the pseudocode sequence indicator is the indication information;
• and
• the transmitting unit is configured to send the integrated signal in a form of a visible light signal;
• wherein
• the pseudocode sequence indicator integrating unit is further configured to integrate the pseudocode sequence indicator into the header of the pseudocode signal, and output a first integrated signal;
• the encryption device further comprises a device addressing code integrating unit, configured to integrate a device addressing code into a header of the first integrated signal and output a second integrated signal;
• and
• the transmitting unit is configured to send the second integrated signal in a form of a visible light signal.