Quantum signal coding method and quantum key extraction method suitable for quantum key distribution

The invention discloses a quantum signal coding method and a quantum key extraction method suitable for quantum key distribution. The quantum key extraction method comprises the following steps of: randomly selecting horizontal, vertical, positive 45-degree or negative 45-degree basis vectors by using a polarization wave plate and a polarization beam splitter to carry out projection measurement on a polarization state of a coded optical pulse signal sent by a sending terminal; randomly inputting a projection measurement result to a first detector or a second detector with asymmetric performance parameters to obtain a measurement result; keeping a measurement result that the measurement basis vector is consistent with the basis vector published by the sending terminal; estimating a channel parameter by adopting a decoy state, and calculating the size of a key rate by utilizing the estimated channel parameter; and extracting a final key from the reserved measurement result according to the key rate. According t