Bug: Message signing; colon cuts off rest of message

[its-DomeE]

When trying to sign a message using the Sparrow Wallet, a colon character : will cut off the rest of the message and therefore doesn't create a valid signature.

In case of e.g. Pocket Bitcoin this will make the Keystone wallet not usable since you have to sign a message in the format of:
Ich bestaetige diese Bitcoin-Adresse alleine zu kontrollieren. Auftragsnummer: ffffffff

Other ASCII characters seem to work fine. I experimented a bit and commas, semicolon, etc. won't cut off a message. But a colon does.

Using firmware v1.8.2

[its-DomeE]

The error seems to lie here:

keystone3-firmware/rust/rust_c/src/common/src/qrcode/mod.rs

Lines 35 to 37 in aa94402

	let mut headers_and_message = value.split(":");
	let headers = headers_and_message.next();
	let message = headers_and_message.next();

The header is split from the message by a colon resulting in additional items which are not checked, if a colon is used inside the message. So maybe this would be resolved if using split_once instead of split?