I think it's not too complicated if you understand that a FLASH memory chipset plus a CPU plus some programming for security needs (in case the wallet is misplaced or stolen) is required.
All this is available in at least three commercially available products, so ye who knows naught of electronics should purchase one instead of trying to learn enough to re-invent that particular wheel.
Oh, and for all of our readers that haven't a clue as to what this is all about: a digital wallet is used to store blockchains documenting digital cryptocurrency transactions, Bitcoin for example. It also stores the encrypted passcodes necessary to access your bitcoins. More convenient that writing the passcode strings (long hexadecimal strings) down on paper. The digital wallets act like memory sticks that attach (temporarily) to a USB port on your Internet-connected desktop computer or laptop for the purpose of securely conducting and storing cryptocurrency transactions.
Pretty neat idea unless you are worried that the imminent quantum computer revolution (less than ten year horizon) will virtually destroy the value of bitcoin mining and lead to a decrease in "value" of cryptocurrency coins as "newly mined" coins rapidly flood the market. Of course quantum computers are to microprocessors as nuclear weapons are to M80 firecrackers... much noisier with far-ranging effects.