In this post I’ll show you how to sign a message on the bitcoin blockchain. The process is more or less the same for the other coins.
To sign a message I am going to use the Electrum desktop light wallet. You can download it here.
Signing a message is important because you can use it as a proof of ownership of your funds, forum accounts or something else. By signing a message from an address you own and control, you make sure of that nobody can troll people for the things you didn’t do or say.
Here is how you do it,
Step 1:
Open electrum, click tools, from the menu click “sign/verify message”
Step 2:
Fill the empty spots. Write a message about whatever you want to tell people. Write down your public address. (Only use the address that you own/control, otherwise it is not going to work!) Then click “Sign”
That’s it!
After you clicked “Sign” the program will generate your signature.
If you later click the “Verify” button, you’ll see a message “Signature Verified”
If you want to verify someone else’s message. You basically fill the empty spaces with the information s/he gave you and again you need to click “Verify” to see if s/he is telling the truth or not.
I hope you'll find this information useful in someday.
http://getinbitcoin.com/2018/12/16/how-to-sign-a-message/
edit:
You can also practice this information you learned here: