In operation 2110, the wearable device 100 may register data transmission authority of the user and a vein image of the user. The data transmission authority may indicate a transmission-available data type and data volume for each user.

In operation 2120, when transmitting the data, the wearable device 100 may control the sensor 110 to capture a vein image of the user wearing the wearable device 100. When the user transmits the data to the outside of the wearable device 100, the wearable device 100 may capture the vein image. When the user transmits the data to external electronic devices, the wearable device 100 may capture the vein image and perform vein authentication before the data is transmitted.

In operation 2130, the wearable device 100 may identify the user wearing the wearable device 100 by comparing the captured vein image with the registered vein images.

In operation 2140, when the identified user has the appropriate data transmission authority, the wearable device 100 may transmit the data. The wearable device 100 may confirm the data transmission authority of the identified user. The wearable device 100 may determine based on the confirmed data transmission authority whether to currently transmit the data. When a type of the data to be currently transmitted is a type in which the user is not authorized to transmit, or a volume of the data to be currently transmitted is greater than a volume in which the user is authorized to transmit, the wearable device 100 may display the message “No Data Transmission” on a display unit 120 and may transmit no data.