Patent ID: 8543811

Claim:
An identity-based ring signature authentication method comprising: generating, by a private key generator, a secret key S t by using public parameters (q, G 1 , G 2 , e, P, P pub , g, H 1 , H 2 ) and identity ID t received from a t th user terminal and transmitting the generated secret key S t to the t th user terminal; setting, by the terminal, (n−1) values (V 1 , V 2 , . . . , V t−1 , V t+1 , . . . , V n ) by choosing an arbitrary random value and generating a first digital signature U on a message m by using the public parameters, the secret key S t , a set (L={ID 1 , . . . , ID n }) of identities of ring members including the identity ID t of a t th user and the (n−1) values; generating a digital signature V t of the t th user by using the first digital signature U, the message m, the set L and the secret key S t ; generating, a plurality of second digital signature including the (n−1) values used to generate the first digital signature U and the digital signature V t of the t th user; generating, a ring signature τ including the first digital signature U and the plurality of second digital signature; and receiving, by an authentication server, the set L, the message m and the ring signature τ on the message m from the t th user terminal and verifying validity of the received ring signature τ by using the public parameter, wherein the public parameters include an elliptic curve group G 1 and a multiplicative subgroup G 2 of a finite field, each of the G 1 and G 2 denotes a group of prime order q, a bilinear pairing e, a generator P of the G 1 , a public key P pub (=s·P) which is a scalar multiplication of the generator P and a master secret key s of the private key generator, a result (g=e(P, P)) of the bilinear pairing e taking as an input the generator P, a first hash function H 1 and a second hash function H 2 .