Hello NotATether.

This was my first bitcointalk post. I was trying to recover some altcoin airdrop for bitcoin holders and I needed to sign a message. Then I discovered it was not possible.

By the time, in 2018, nullius gave me some technical details about the problems for creating this standard.

Take a look, it might help you:

Quote from: nullius on February 05, 2018, 01:24:34 PM

Known issue. There are some subtle problems here. I’ve wanted to kick around ideas for a potential BIP, but it’s been fairly low on my list.

https://github.com/bitcoin/bitcoin/issues/10542

https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-December/015374.html

https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-December/thread.html#15374

See especially:
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-December/015441.html

(I seem to recall further discussion last month, but I can’t find it now. It may be a memory bitflip.)

Quote from: jtipt on February 05, 2018, 01:01:18 PM

OP which wallet are you using? Because electrum can very well sign and verify messages signed from bech32 addresses. I think some of the other segwit wallets like samurai don't have a feature to sign message yet. I'm assuming since electrum can sign message then bitcoin core 0.16 also should be able to do that when its released.

Just signed one with electrum.

Code:

Message: Signed message
Address: bc1qyjqygpulgd6y69ync6wvd256qjltszekd2pz0x
Signature: HwNkc1x7GtforrqObazbOOure4XV5Jpx51Uf/dQ7hLQNEhkO+914HqUupdYJd3LH0eBtfENXBWRj3mb+HbQOoDw=

I know this, too. I have not yet tried to figure out what Electrum is doing; but it’s nonstandard. Core cannot verify those signatures (as I know for certain), and AFAIK that will not change with v0.16.