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I used openAI, and she said this address is invalid, thanks for the reply.
There's a reason why ChatGPT answers are banned in multiple platforms and forums, that's on example.
I've also seen users here who referenced ChatGPT answers and some are too generic, if not, incorrect.
Give it a few more years before taking its answers into account.
I wanted to know if signing a message with invalid address was possible or not.
If it was possible, wouldn't everyone sign a message with any address they wish to? I guess this would break all the security rules of bitcoin, lol.
I think you misunderstood the question.