Is the airdrop registration at
https://bitcore.cc/airdrop.php currently broken? I get "Error: BTX public key (your address) or signed message not valid" even though my signed message is valid (I have done similar message signing for Byteball, which worked fine).
Did you copy your complete signed message, including the "=" at the end?
The problem seems to be that I used a Bitcoin wallet to sign the message, not Bitcore. They give different signatures, I guess because Bitcore's strMessageMagic in validation.cpp has "BitCore Signed Message:" instead of "Bitcoin Signed Message:". (And I don't think it's possible to convert one signature to the other, but someone please correct me if I'm wrong.)
Could the airdrop registration be modified to accept both types of signatures?
The issue is that my private keys are in a Trezor, and I'd prefer to have my Trezor sign the message, rather than exposing my private keys or moving my coins to a different wallet. (The Trezor can sign transactions to send BTX without modifying the firmware; but for signing a message, the firmware is hardcoded to use the "Bitcoin Signed Message:" prefix, so it can't be used for registering for the airdrop.)