Bitcoin Forum

Here's a 2BTC bounty for anyone who can explain from start to finish how to sign a message from a bitcoin address in electrum. The following assumptions should be made before answering:

• This is the first time I've used Electrum desktop client
• The message needing to be signed is multi-lined
• I must use Electrum, nothing else

Make sure electrum is running so do sanitycheck: ( this is done in shell terminal or windows command promp!)


then see what this command tells you. If not works then go to directory where you downloaded electrum and try

and should come back as


If it works and you can reach electrum through terminal and get some response back then you can next do this:


Where is <address> put your address which one you want to prove you have control over.
Where is <message> just copy paste the full message with how many lines you need but make sure to convert it from multiple lines to one LONG line with notepad or something so it is just one huge long line instead of multiple line with space inbetween.

Hope i helped!
Address is 1EvCVytASszoUq6S7ioPaLQScjg8ptt5s9 if you feel generous.
If no works then post here and I can help again

If you really need to have a multi-line message, you could just first hash it with SHA-256 (for example, here (http://www.xorbin.com/tools/sha256-hash-calculator)) then sign the hash!

note: if the address you want to sign with is not in your Electrum wallet, you need to import it first:

oh, I did not see that you wanted a multi line message.
you can use \n for new lines:

Example:


and to verify:

which OS are you using?

the electrum code doesn't handle it very well:

sign:
message = ' '.join(args[2:])
wallet.sign_message(address, message, password)

verify:
message = ' '.join(args[3:])
wallet.verify_message(address, signature, message)

If you feel fine changing the code yourself, you can replace the message= commands the following way:

for signmessage:

message = ' '.join(args[2:])


try:
    f=open(args[2],'r')
    message = f.read()
except IOError as e:
    message = ' '.join(args[2:])


for verifymessage:

message = ' '.join(args[3:])


try:
    f=open(args[3],'r')
    message = f.read()
except IOError as e:
    message = ' '.join(args[3:])


This will change the default behavior to reading the message from the file if it exists.

ADDENDUM: If you feel this is a critical feature you may want to suggest this code to the electrum developer...

btw, there seems to be a bug with verifymessage on Windows.
see https://bitcointalk.org/index.php?topic=50936.msg1135155#msg1135155

follow up: apparently, on Windows you need to add quotes around the signature, like this:

did you solve problem? who receive bounty? :)

Were you planning on signing 10k anytime soon?

By the way, if you are using the Windows builds, note that you need to open the text console first, by holding the SHIFT key down on your keyboard while launching Electrum.

Apart from that, the above posts pretty much nailed it, but I will summarize the process from start to finish:


A. To sign a message using an imported address:

1. Hold SHIFT down while launching Electrum
2. Import your address by typing:
    e -o import 1YourBitcoinAddress:5YourPrivateKey
3. In the virtual console that has appeared, type:
    e signmessage 1YourBitcoinAddress "MessageLine1\nMessageLine2\nMessageLine3"
  
    This should output the base64-encoded cryptographic signature.    


B. To verify a signed message:

1. Hold SHIFT down while launching Electrum
2. In the virtual console that has appeared, type:
    e verifymessage 1YourBitcoinAddress "TheSignature" "MessageLine1\nMessageLine2\nMessageLine3"    
     (Be sure to include the quotes.)

   If successful, this must return True.  


Note that all of the above can be performed on a non-networked computer, if preferred.

PS: hopefully in a future release, these commands will be accessible from the graphical interface. For now, they are only available through the advanced console.

so who got the bounty?
my address is 1EvCVytASszoUq6S7ioPaLQScjg8ptt5s9
i hoped to win 2BTC for helping but what happen :'(
i though bounty supposed to be given out-amirite?

Sent! (I'll be using Bitcoin-QT afterall but I pay my bounties regardless ^^. Cheers!)

Thanks everyone. Electrum is apparently no where near user friendly enough to use.

received. many thx!

Just trust that we are working every day to make it better. Building verification/signing into the GUI is pretty high on my list :)