In order to solve the potential security 
hazard problem existing in RFID, the invention provides a 
security system applied to an electronic tag. The 
security system comprises an RFID 
chip, a reader and an unsymmetrical cryptographic 
algorithm, wherein the RFID 
chip is provided with tag memory codes of a 
Faraday cup and a memory switching key; the reader is provided with a 
detector; and the unsymmetrical cryptographic 
algorithm with the following improvement is arranged between the RFID 
chip and the reader. The 
algorithm comprises the steps of initially permuting, inversely permuting, transmitting a Query 
authentication request to the electronic tag by the electronic tag reader, generating H(IDkIIR), putting forward a request for obtaining all electronic tag marks to a backend 
database by the electronic tag reader, automatically marking the electronic tag reader by the backend 
database, authenticating the electronic tag reader, verifying the electronic tag, and the like.