title: Remotely Writable NFC Tags
body: <p>I am developing a solution to open doors via NFC tags. These NFC tags will only hold the door identifier, with which the door can then be opened. However, I want to prevent people from reading the identifier once and then sending the identifier to a friend who could then remotely start the door opening process.</p>
  
  <p>So far, the system used QR codes that were displayed on screen and changed every 10 seconds. The QR codes contained secrets that were only valid for a few minutes.</p>
  
  <p><strong>Do you know of any NFC tags or tag emulators that are capable of being rewritten remotely, e.g., via WLAN?</strong></p>
  
  <p>For example, is it possible to emulate an NFC tag using a Raspberry Pi, and to then change the content of the emulated tag every 10 seconds? Are there even cheaper, smaller, or more simple solutions?</p>
  
  <p>I realize that this question is not a software question and I apologize, but StackOverflow is my go-to place for technical questions and I am sure you can help me or point me to a place where I am helped.</p>