Method and system for error correction in quantum cryptography communication

A quantum cryptography communication method between at least one first communication device and at least one second communication device performed by at least one processor, the method comprising:

• a quantum communication step of generating a second information sequence based on a first information sequence by the second communication device, when the first communication device transmits the first information sequence generated by randomly modulating by a phase or polarization of photons to the second communication device;
• and
• a post-processing step of adjusting the first information sequence and the second information sequence to be identical using parity information in an error correction mode selected based on a predetermined criterion, wherein
• the error correction mode is one among a first error correction mode in which when the first communication device encodes and transmits first parity information to the second communication device, the second communication device decodes the encoded first parity information to adjust the second information sequence to be identical to the first information sequence, and a second error correction mode in which when the second communication device encodes and transmits second parity information to the first communication device, the first communication device decodes the encoded second parity information to adjust the first information sequence to be identical to the second information sequence, and
• the predetermined criterion is selecting the first error correction mode as the error correction mode when an eavesdropper is located near the second communication device more than the first communication device, and selecting the second error correction mode as the error correction mode when the eavesdropper is located near the first communication device more than the second communication device.

A quantum cryptography communication system comprising:

• a first communication device for transmitting a first information sequence generated by randomly modulating by a phase or polarization of photons to a second communication device;
• and
• the second communication device for generating a second information sequence based on the received first information sequence, wherein
• quantum key distribution is performed through an error correction process of adjusting the first information sequence and the second information sequence to be identical using parity information in an error correction mode selected based on a predetermined criterion, and
• the error correction mode is one among a first error correction mode in which when the first communication device encodes and transmits first parity information to the second communication device, the second communication device decodes the encoded first parity information to adjust the second information sequence to be identical to the first information sequence, and a second error correction mode in which when the second communication device encodes and transmits second parity information to the first communication device, the first communication device decodes the encoded second parity information to adjust the first information sequence to be identical to the second information sequence, and
• the predetermined criterion is characterized by either (a) or (b):
• (a) the predetermined criterion includes a first criterion in which a communication device without a detector placed therein, among the first communication device and the second communication device, performs encoding of the parity information, and a communication device with a detector placed therein, among the first communication device and the second communication device, performs decoding of the parity information, and a second criterion in which any one among the first communication device and the second communication device performs decoding of the parity information on the basis of signaling information including information on a subject of decoding the parity information,
• (b) the predetermined criterion is selecting the first error correction mode as the error correction mode when an eavesdropper is located near the second communication device more than the first communication device, and selecting the second error correction mode as the error correction mode when the eavesdropper is located near the first communication device more than the second communication device.