Physically securing passive devices with smart phones

A method of unlocking a lock assembly, the method comprising:

• producing, by a mobile device, light;
• and
• encoding, by the mobile device, a key in the light produced by the mobile device, wherein the lock assembly comprises circuitry comprising:
• an optical-to-electrical converter device configured to generate an electrical signal when illuminated by the light produced by the mobile device;
• a key reader configured to be powered by the electrical signal and, when powered, to read the key encoded in the light and to generate a key signal in accordance with the key;
• and
• a processor configured to be powered by the electrical signal and, when powered, receive the key signal and determine a validity of the key in accordance with the key signal, the processor further configured to, when powered and the key is valid, generate a switch signal;
• and
• a locking device coupled to the circuitry and configured to be powered by the electrical signal, the locking device configured to switch between a locked configuration and an unlocked configuration, the locking device further configured to, when powered, receive the switch signal and, when the switch signal is received, switch from the locked configuration to the unlocked configuration.