Key distribution method, device and system

The invention provides a key distribution method, device and system. The method comprises the following steps: an identity management server judging whether the terminal passes the AAA authenticationor not according to the AAA authentication information in the ID registration request message sent by the terminal; if the terminal passes the AAA authentication, an ID is distributed to the terminal,sending the ID of the terminal to the key management server, and the key management server generating a private key of the terminal according to the ID of the terminal and returns the private key tothe identity management server; after the identity management server negotiates with the terminal to generate a first secret key, encrypting the ID and the private key of the terminal through the first secret key and sent to the terminal, and the terminal decrypting the ID and the private key through the first secret key after receiving the ID and the private key of the terminal. According to thekey distribution method, dev