Method of controlling electronic device using wearable device and method of operating electronic device

A method of operating an electronic device, comprising:

• pairing the electronic device with a wearable device;
• receiving an unlock signal from the wearable device when a distance between the wearable device and the electronic device is smaller than a threshold distance;
• and
• unlocking a lock system of the electronic device based on the unlock signal.

A wearable device for controlling a paired electronic device, the wearable device comprising:

• a communication device;
• a secure storage device configured to store a cryptographic key which corresponds to the electronic device;
• and
• a processor configured to, in combination with the communication device and the secure storage device, estimate a distance between the wearable device and the electronic device, and transmit an unlock signal including the cryptographic key, which is stored in the secure storage device, from the wearable device to the electronic device when the estimated distance is smaller than a threshold distance to unlock the electronic device.