An identity authentication system comprising an identity authentication request apparatus and an identity authentication apparatus, wherein the identity authentication request apparatus is a mobile phone light key, wherein the identity authentication request apparatus is configured to send a verification code issuing request to the identity authentication apparatus (S 1202); the identity authentication apparatus is configured to respond to the verification code issuing request sent by the identity authentication request apparatus, generate an ID and a corresponding verification code according to the verification code issuing request, bind the generated ID and the verification code, store the generated ID, the verification code, and a binding record, and feed back feedback information that carries the verification code to the identity authentication request apparatus, wherein the ID is used for uniquely identify the mobile phone light key; the identity authentication request apparatus is further configured to receive the feedback information, from the identity authentication apparatus, and send an ID issuing request to the identity authentication apparatus, wherein the ID issuing request comprises the verification code carried in the feedback information; and the identity authentication apparatus is further configured to parse the received ID issuing request and determine whether the verification code comprised in the ID issuing request matches the stored verification code, and if the verification code comprised in the ID issuing request matches the stored verification code, send allocation information that carries the ID, which is stored in the identity authentication apparatus and bounded with the verification code, to the identity authentication request apparatus; wherein the identity authentication apparatus is further configured to perform channel encryption for the feedback information that carries the verification code before the feedback information that carries the verification code is fed back to the identity authentication request apparatus; wherein algorithms used for the channel encryption comprise a time-based sync encryption algorithm, the performing channel encryption by using the time-based sync encryption algorithm comprises: acquiring current time information; adding the time information into the feedback information or the allocation information; generating or selecting a group of scrambling codes according to the time information; and performing scrambling for the feedback information or the allocation information by using the generated or selected group of scrambling codes; wherein, the identity authentication request apparatus is further configured to decrypt encrypted information received from the identity authentication apparatus, so as to extract the time information; if a time in the time information is greater than a time stored in the identity authentication request apparatus, determine that the verification code fed back or the allocated ID is legal; otherwise, if the time in the time information is less than or equal to the time stored in the identity authentication request apparatus, determine that the verification code fed back or the allocated ID is illegal.