Systems and methods for operating a security tag. The methods involve: receiving, by the security tag, an authorization code comprising a security tag identifier signed using a cryptographic key of a plurality of cryptographic keys that are respectively assigned to a plurality of security tags; performing operations by the security tag to verify a signature of the authorization code; and performing detach operations or deactivation operations by the security tag, responsive to the signature's verification. The detach operations cause a mechanical detachment of the security tag from an item. The deactivation operations cause a disablement of a response by the security tag to an interrogation signal from a Radio Frequency Identification ("RFID") system or an Electronic Article Surveillance ("EAS") system.