Touch-sensitive Alphanumeric Encrypting PIN Pad Design Based on Hamilton-connected Subgraph Recognition

The encrypting PIN pad (EPP) is one common interface used to verify the authentications for such as access control management, automatic teller machine (ATM), etc. by entering personal identification number (PIN). However, the strength of the passwords composed of ten candidate digits is less than 30% of with alphanumeric inputs by additional 26 English alphabet letters. This paper proposes an alternative alphanumeric EPP solution by using touch-sensitive technology based on the theory of Hamilton-connected subgraph. The experimental result for the design shows that the one-stroke operations are feasible and the recognitions are accurate for the proposed alphabet patterns.