Abstract: An identity certificate may be issued to a blockchain node. The issuance may include issuing a first identity certificate to a first terminal and receiving a second identity certificate issuance request that is from the first terminal. A second identity certificate may be issued to the first terminal, and a third identity certificate issuance request is received from the second terminal. A third identity certificate is issued to the second terminal, so that the second terminal forwards the third identity certificate to the third terminal.

Abstract: A digital photo frame having dual display panels of the present invention includes a frame body, a foot, a microprocessor, an output and input interface, an external connecting storage device, a multiplexer, a first buffer unit, a second buffer unit, a third buffer unit, a first display panel, a second display panel and a control panel. When a portrait mode photo is desired to be displayed, the microprocessor sends the photo to the first buffer and to display the photo in the first display panel. When a landscape mode photo is desired to be displayed, the microprocessor sends the photo to the second buffer and to display the photo in the second display panel. Hence the present invention can avoid incorrect display ratio of the photos.