Electronic User Authentication Key for Access to HMI/SCADA via Unsecured Internet Networks

Figure 2

Hardware components of the electronic key. (a) Arduino Pro Micro (ATmega32U4) [42]; (b) 0.91 OLED display module 128 × 32 [43]; and (c) button clock model A24 [44].

(a)

(b)

(c)