Single sign-on method, server and system based on blockchain

The invention provides a single sign-on method, server and system based on a block chain, and the method comprises the following steps: feeding back an information file comprising the address of the server to a first user terminal after receiving a login request transmitted by the first user terminal; receiving a user ID sent by a second user terminal; obtaining a public key corresponding to the user ID and the encrypted identity attribute from the blockchain; sending an identification attribute range and a random number corresponding to the encrypted identity attribute to a second user terminal; receiving a secret key corresponding to the encrypted identity attribute and a signed random number fed back by the second user terminal; and decrypting the encrypted identity attribute accordingto the public key, the secret key and the signed random number to obtain the identity attribute, and responding to the login request according to the identity attribute. An identity provider is canceled, so that a user manage