Patent ID: 7881472
Filing Date: 2011-02-01
Classification: H03M,H04L

Abstract:
1. A quantum-key distributing method for a quantum cryptographic system including a transmission-side communication apparatus that transmits a random number sequence forming a basis of an encryption key in a predetermined quantum state on a quantum communication path and a reception-side communication apparatus that measures a photon on the quantum communication path, the quantum-key distributing method comprising: transmitting and receiving including the reception-side communication apparatus maintaining reception data with probability information obtained as a result of measuring a light direction with a measuring device for correctly identifying the light direction; and the transmission-side communication apparatus maintaining transmission data corresponding to the reception data; information notifying including the transmission-side communication apparatus notifying, via a public communication path, the reception-side communication apparatus of error correction information generated based on a parity check matrix, of which elements are “0” or “1”, and the transmission data and error detection information generated based on a cyclic code for detecting an error and the transmission data; transmission-data estimating including the reception-side communication apparatus estimating the transmission data based on a same parity check matrix as that of the transmission-side communication apparatus, the reception data with probability information, the error correction information, and the error detection information; and encryption-key generating including the transmission-side communication apparatus and the reception-side communication apparatus discarding a part of the transmission data according to an amount of information laid open to the public communications path and generating an encryption key using rest of the transmission data.