The present invention provides a security authentication method, a configuration method, and a related device. A first terminal receives a public key for signature of a configuration device sent by the configuration device. The first terminal receives second signature information and second type information. The first terminal determines, according to at least the second type information and the second signature information, that the first terminal is to generate key information. In this way, the first terminal establishes a security connection between the first terminal and the second terminal. This effectively prevents a terminal from tampering with its role, and therefore effectively prevents a terminal from establishing a connection to an attacker terminal with a changed role, thereby further preventing the attacker terminal from obtaining information of the terminal, to effectively ensure security of the terminal.