USB Password Keeper Runs On Tiny Chip

The most important rule of password use, especially when used for online logins, is to avoid reusing passwords. From there, one’s method of keeping track of multiple passwords can vary considerably. While memorization is an option in theory, in practice a lot of people make use of a password manager like Lastpass or KeePass. For those with increased security concerns, though, you may want to implement a USB password keeper like this one based on an ATtiny.

This password keeper, called “snopf”, is a USB device with an ATtiny85 which adds a layer of separation to password keeping that increases security substantially. Passwords are created by the USB device itself using a 128-bit key to generate the passwords, which are physically detached from the computer. Password requests are made by the computer to the USB device, but the user must push a button on the snopf in order to send the password to the computer. It does this by emulating a keyboard, keeping the password information off of the computer’s clipboard.

Of course, snopf isn’t perfectly secure, and the project’s creator [Hajo] goes into detail on the project’s page about some of the potential vulnerabilities. For most use cases, though, none of these are of serious concern. Upgrading your password keeper to a physical device is likely to be a huge security improvement regardless, and one was actually developed on Hackaday a few years ago.

37 thoughts on “USB Password Keeper Runs On Tiny Chip

        1. The USB is the whole reason the internal oscillator is preferred. None of the common crystal speeds are perfect for USB, but the internal oscillator in the ATTiny85 is very accurate and precisely tuneable. It is not comparable to the more typical case of using an internal oscillator. That feature is a major part of why the `85 exists and why it is used in USB devices.

    1. I think this should be possible, all you really need is an ATtiny85. And it looks as if the digispark board uses software USB for communication too? No idea though how much space is left on the board (I guess there is a bootloader on the chip already?) and you’d have to adjust the V-USB driver to use the chip’s oscillator etc.

    2. On some microcontrollers you can use the ADC to get capacitive touch detection with no extra hardware: you can detect the user just touching the pin. There are Arduino libs for this. I think I saw an online discussion that you can do this on a Digispark, too.

    1. I don’t remember the details anymore but I didn’t like the password generation / storage details for the yubikey. (IIRC it was pretty restricted in number of passwords etc.)
      Apart from that, it kinda resembles a yubikey for services that don’t allow for 2FA / FIDO2..

        1. No I meant I don’t know whether it’s worth prodding you into making it, then lugging a bluetooth sniffer on a yagi out to your neighbourhood and following you around for hours, because you might only be using it for instagram and tumblr :-D

          1. I just finished it. When lit the device tries to pair – you can check on your computer if it does or not and you need a pin to confirm. Then you can send the password.

          2. It is just like a rusty chain; people look at it and worry, but the rust is only on the outside surface and the strength of the chain hasn’t changed.

            As for lifting the the gate of it’s hinges, if you found that, tell a security researcher so they can credit you when they publish, you’re going to be famous!!!

    1. I don’t think it is that easy, because the way this password keeper works is, that the computer/browser plugin sends a request for a certain account/website to the password keeper via usb. The password keeper than looks for the password for that account and only send it after the user pushes the button. I don’t know if the request part is that easy via bluetooth.

      1. My version is simpler : I have a two buttons device. The first one is a “mode” button allowing you to select different password options. The second one is a “log” button sending the code as a bluetooth keyboard. As simple as that !

    1. Yes, there are some other options as well, Mooltipass is another example. And I think 2FA/FIDO2 is a nice development. But so far there are still many services that still just rely on passwords only.

      TBH I built snopf because for every product I found there was something I wasn’t happy with (tech, not open source, handling..). But I guess that also includes NIH syndrome. ๐Ÿ™‚

    1. Yes there is a good way to back up the key!
      You should set the key on the device yourself anyway and you can get the key as a 12 word mnemonic to safely store it somewhere (or write it to a second device)

    1. if you would read on the github page, there is an app for that, and for my android with USB C at least, I have an USB 2.0 A to USB C adapter on my key chain. I use it for my typical usb stick (USB 2.0 A) and my FIDO stick if I need it on my phone.

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