How a reading works.

The computer prepares, the rail decides

A program on a computer can assemble the details of a request. It cannot complete that request. The details travel down the USB-C cable into Aurora Root, and they stop there until the line has been read and the dial has been pressed.

The program’s own window is a draft. The horizontal line is the record. If the two disagree, the line is the one that matters, and the dial stays up.

What the line is willing to show

The chip draws the request in words it can fit on the glass: what is being asked, where it is aimed, and a warning if something in the request looks unlike the ones the rail has seen before. You step through that text with the square key. Nothing is signed while you are still stepping.

The teal slit stays lit for the length of this look, then goes out. That light is a lamp for the chip, not a signal to anything else in the room.

The press

Pressing the silver dial is the confirm. The chip signs, and only the signature leaves the rail. The private key does not. If you clear the line with the square key, or if you unplug the cable and let the cell sleep, the request ends without a signature.

The same discipline covers setup. The chip creates the key on the rail. The 21-word phrase appears once, on the line, so it can be written on paper. After that screen, the rail does not show the phrase again. Goingclear, Inc. does not ask for those words. The essay on the paper is the longer version of that rule.

More on the parts themselves sits on the device page.