Multi-antenna key security generation and distribution method and device under line-of-sight transmission

The invention provides a multi-antenna secret key security generation and distribution method and device under line-of-sight transmission, and relates to the field of secret communication. The central user Alice generates a root key according to the time-varying distance data with the legal user Bob and the local noise data; the legal user Bob uses a sum beam to transmit a random pilot frequency to the center user Alice, uses a difference beam to transmit first artificial interference to the eavesdropping direction, and forms null in the center user Alice direction; the central user Alice scrambles the coded and modulated root key according to the random pilot frequency to obtain a scrambled root key; the central user Alice transmits a scrambling root key to the legal user Bob direction by using a sum beam, and transmits second artificial interference to the eavesdropping direction by using a difference beam, and a null is formed in the legal user Bob direction; the legal user Bob descrambles the scrambling r