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.

  • Unfortunately it's not possible.
    – MCCCS
    Jan 16, 2018 at 13:30
  • Is that a fundamental limitation or can it be programmed to do so?
    – Elias Naur
    Feb 2, 2018 at 16:34
  • It's actually a good suggestion, you should ask Trezor devs: gitter.im/trezor/community
    – MCCCS
    Feb 3, 2018 at 14:26
  • Don't do it - printers have really weak security - would never print a private key that should hold any value
    – ligi
    Feb 4, 2018 at 23:30

1 Answer 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

  • Can you expand on the reason(s) this is insecure?
    – Elias Naur
    Feb 6, 2018 at 0:17
  • I edited my answer adding some reasons. Hope this helps understanding the problem.
    – ligi
    Feb 6, 2018 at 10:46
  • 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
    Feb 7, 2018 at 11:20

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