This is Windows Phone application, wich utilize NFC features of phones.
Tap Hint application provides the ability to secure or plain storage for the text hints or codes in NFC tags. The information you entered is stored in the NFC tags in encrypted AES format or in plain UTF encoded text. The encryption key is a unique identifier for the phone. To allow the use of the key automatically without having to type it manually. This makes it impossible to read the safe hints, using other devices. Plain text hints can be read with another devices.