An identity authentication method and a device based on a block chain

The present application discloses an identity authentication method and device based on block chain, The method includes: the first block chain node determines at least one second user associated withthe first user according to the identity information of the first user, and sends an authentication request to the at least one second block chain node logged in by the second user, wherein the authentication request includes the identity information of the first user; the authentication information sent by at least one of the first block chain nodes is received, and the identity of the first user is authenticated according to the authentication information and the set identity authentication contract. By virtue of the untamperable nature of the block chain network, the identity of the traderwho has not been authenticated is authenticated by the trader who has the authority to authenticate, and according to the generated authentication information and the set identity authentication contract, trader identity auth