Connect Trezor (T) directly to a printer to generate paper wallets

2

Is it possible for a Trezor or Trezor T to connect with and directly interface with a printer? The Mycelium Entropy device is very useful to print paper wallets while minimizing MITM attacks. I'd like the Trezor to do the same.

Elias Naur

Posted 2018-01-16T13:16:11.093

Reputation: 121

Unfortunately it's not possible. – MCCCS – 2018-01-16T13:30:26.083

Is that a fundamental limitation or can it be programmed to do so? – Elias Naur – 2018-02-02T16:34:37.717

It's actually a good suggestion, you should ask Trezor devs: https://gitter.im/trezor/community

– MCCCS – 2018-02-03T14:26:52.910

Don't do it - printers have really weak security - would never print a private key that should hold any value – ligi – 2018-02-04T23:30:29.717

Answers

1

It is a feature that this is not possible. You do not want to use a printer to print paper wallets as this is highly insecure. Printers have a track record of having low security - so people can hack the printers - wait for it to print something that looks like a private key and send them home(not yours). Also some printers have build-in hard drives that save every document printed - so there are also attack vectors where the printer does not need to be compromised before printing. Also have a look here: https://events.ccc.de/congress/2011/Fahrplan/events/4780.en.html https://media.ccc.de/v/28c3-4780-en-print_me_if_you_dare

ligi

Posted 2018-01-16T13:16:11.093

Reputation: 143

Can you expand on the reason(s) this is insecure? – Elias Naur – 2018-02-06T00:17:41.163

I edited my answer adding some reasons. Hope this helps understanding the problem. – ligi – 2018-02-06T10:46:16.923

I'm using the USB-interface on the printer exactly to avoid these security issues. The printer does not have wireless networking and its network port has never been connected. In fact, it has never been connected to anything other than USB-sticks and the Mycelium Entropy. Of course, there is still a risk, but nowhere big enough to rule out this mode of cold storage. – Elias Naur – 2018-02-07T11:20:43.413