SECRET COMMUNICATION METHOD AND SECRET COMMUNICATION DEVICE THEREOF
A secret communication method and device are described using a communication path less frequently as a whole while avoiding a duplicative use of public communication. The method includes: estimating an error ratio of initial random numbers X, Y
estimating the upper limit of an eavesdrop information amount
determining an encryption function determined by the error correction code based on the estimated error probability, an error correction decoding function, and a decryption auxiliary variable
determining a confidentiality increase matrix C based on the estimated upper limit of the eavesdrop information amount and the encoding ratio of the error correction code
generating a ciphertext from information to be sent using the encryption function, the initial random number X, and the confidentiality increase matrix C.
Once received, the ciphertext is decrypted using the initial random number Y, the confidentiality increase matrix C, the decryption auxiliary variable, and the error correction decoding function.