python-trezor 0.9.1 required for Trezor T support

[mocmocamoc]

The release notes for Electrum 3.1 say that "The Trezor T hardware wallet is now supported", but at least on Windows this doesn't work with python-trezor 0.9.0 which appears in requirements-hw.txt for 3.1. Electrum 3.1 as released just hangs when trying to create a wallet using a Trezor T. For it to work requires python-trezor 0.9.1 which was tagged a couple of hours after Electrum 3.1.

Tangentially, the Windows build also includes libusb 1.0.21 which has a bug affecting the enumeration of Trezor Ts: trezor/python-trezor#223
The bug is fixed in libusb 1.0.22-rc3 but I don't know if it would be appropriate to include that in the build.

[SomberNight]

Well I've only tested on Ubuntu, with the emulator, but apart from passphrases ( #3996 ), it works for me on 0.9.0.

[SomberNight]

As for the libusb thing; the potential error is that a hw device is listed twice in enumeration, but otherwise it's harmless, right? In that case I think we can wait for a full release of libusb; and feel free to remind us when that happens :)

[mocmocamoc]

I've tested 0.9.0 on Ubuntu now and I see the same behaviour as Windows, it hangs when performing any interaction with the Trezor T. It works as expected with python-trezor 0.9.1. This is with a real device, so if it works with the emulator then it may be a difference in behaviour between the emulator and the device.

[mocmocamoc]

This is the important commit to trezorlib: trezor/python-trezor@4cfcd93

Evidently there was a "v2" protocol that was intended to be used by the Trezor T, but it was removed from the device (and hence the emulator) on 27th Feb: trezor/trezor-core@323714d

So I'd guess that the emulator code you tested with predates 27th Feb, meaning it supports the v2 protocol, which means it works with trezorlib 0.9.0 whereas a real device will not.

TL;DR: If you update the emulator code to latest and test again then I think it will display the same behaviour as I'm seeing with the device?

[SomberNight]

That sounds plausible.
However, I've just tried with Electrum 3.1.0, python-trezor 0.9.0, and git HEAD trezor/trezor-core@a697d48 of trezor-core, on Ubuntu, and it worked as long as I did not enable passphrases.

It might be due to emulator / real device differences though.
I really should get a real device; but I'll have to wait until they enable orders.

In any case, python-trezor 0.9.1 will be included in the binaries for the next release, there isn't much else we can do anyway. We will probably do a minor release relatively soon.

[mocmocamoc]

Thanks, moving to 0.9.1 should sort it out.

I investigated a bit further, so in case you're curious: the emulator works with trezorlib 0.9.0 because the emulator is seen as a UDP device (rather than a WebUSB device like the real thing), and in 0.9.0 UDP devices were already forced to use protocol v1: https://github.com/trezor/python-trezor/blob/v0.9.0/trezorlib/transport_udp.py#L53

[SomberNight]

Ahhh; indeed I should get a real device. :)

[SomberNight]

Can you confirm that the Windows binaries for Electrum 3.1.1 can detect the Trezor T?
A user claims they don't :/