You can sign a message with any address you have control. A "used address" is still a regular address just like any other, but may be labeled like this to prevent you from using the same address more than once by mistake in case you care about privacy.
1. What is your wallet software?
Read this thread on how to sign a message with several major wallets: https://bitcointalksearch.org/topic/how-to-sign-a-message-990345
1. What is your wallet software?
Read this thread on how to sign a message with several major wallets: https://bitcointalksearch.org/topic/how-to-sign-a-message-990345
I use blockchain.info and get my priv key through my 12 word seed under the electrum wallet. I tried signing the message with the available address but when I tried to submit to bitcore claim it told me the signiture was invalid
