Identity authentication circuit, system thereof and electronic transaction method

Disclosed are an identity authentication circuit, a system thereof and an electronic transaction method. The circuit is for being built in or connected with an electronic device to allow a user to carry out electronic identity authentication with his or her unique biomedical features on a remote server. The identity authentication circuit comprises a memory unit, an acquisition unit, a processing unit and a communication unit. An authentication key code is stored in the memory unit. The acquisition unit acquires the biomedical features and generates a corresponding biomedical feature code. The processing unit processes the authentication key code and the biomedical feature code according to a process to generate a corresponding unverified code, and the communication unit transmits the unverified code to the server and awaits the authentication result of the electronic identity authentication. Further, the present invention also provides a related authentication system and an electronic transaction method.