A system according to an embodiment includes electronic lock and key of which the electronic lock can be installed on a portal such as a door. The electronic lock is capable of contact-less authentication of the electronic key carried in person by a user, and also determines the open/close condition of the door panel with respect to the door frame. Being an add-on, there is no need to replace or modify the existing mechanical lock at the door. The electronic key does not require any batteries to operate, being powered by the electronic lock through wireless transfer of power through the door panel. After a successful authentication of the electronic key, the electronic lock clears the user to open the door. An attempted illegal entry by force or using duplicate key of the mechanical lock without electronic authentication is considered intrusion. Once an intrusion is detected, the system generates an alarm at the premises as well informs multiple mobile devices (e.g., cell phone) anywhere in the world through a wireless network. The electronic lock can be powered by a battery or AC source depending on the installation scenario.