I recently asked a question Can applications push themselves in Windows?

where an appealing answer wrote that

Pushing it simply creates an electrical connection. There is no program stored in the web cam, so nothing is being "pushed" to the OS.

In a USB key there are no buttons. So my question/s is/are

1. Does a USB password key push the password to the operating system?

2. How does the USB password store the key?

I recently came across the ATtiny85 which can be used for the purpose of the key.

Is this device capable of pushing data/commands/passwords to the OS?

1 Answer 1


It pretends to be a HID and keys in the password emulating a keyboard.

In fact, there's boards based on microcontrollers that can emulate or act as a controller for a keyboard - most famously the teensy, and similar devices uses for good and evil.

Since every modern PC uses a standard USB keyboard, no additional drivers are needed.

  • Can a USB key store many password? if yes how does it know which pwd?
    – Vedant
    Nov 16, 2016 at 20:30
  • 1
    In theory, yes, but you'd need some form of input/output for that. Something like the mooltipass, while not a simple key would work. or the key stores a key which is used to verify your identity, like with U2F
    – Journeyman Geek
    Nov 17, 2016 at 0:18

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