>It's not possible to sign an arbitrary message with any sort of signature scheme by Trezor. > >It would be really stupid to allow this: if the message is arbitrary, you can stuff in, say, a valid Bitcoin transaction. Then it's a matter of crafting a clever malware, telling the user: "Security check: please confirm the following characters on your Trezor screen to validate your wallet", and stealing their money. > >The SignMessage APIs look like they accept an arbitrary message, but they don't sign it: the data that is actually signed is "Bitcoin Signed Message:\n(11 bytes)hello world" or something along these lines. > >Even if that is good enough for you, this feature currently does not support Schnorr signatures :( because there hasn't yet emerged a standard for taproot message signing. Source:

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