You are 100% right.

That warning was for people not to message me or the forum their private keys... it happened already
 
Relatives should obviously be treated differently.

Hi All,

ICOs are quite complicated for first-time contributors so I thought I would share my experience.
Most contributors face the same challenges and ask the same questions... One of them being "how to sign a message with my Bitcoin address"?

Here is the (at least one) answer.

Context:
- I used Electrum (portable version) but the procedure should be relatively similar with most wallets that let you control your private keys.
- I tested that procedure with the Windows and Linux versions of Electrum. Sorry Apple users
- The private keys used in that example are worthless and I will discard them once that message published. Do not publish/share yours.

Pre-requisite:
You need the the private key of the address you want to sign the message with.
If you need the private key of an address in a Blockchain wallet click here https://bitcointalk.org/index.php?topic=2517669.0.

  1. Download and install Electrum https://electrum.org/

  2. Create a new wallet (default type)


  3. Import the address you want to sign the message with. The address has to be added to the wallet you have just created in step #2 as it needs the private key to sign the message.


  4. Once the address available in your wallet click on "View > Show addresses" (the path might differ slightly depending on your OS/the version of Electrum)


  5. Fill the form:
    - Message is whatever you want to send to prove you are the owner of the address. Typically a username or an email address.
    - Address is the Bitcoin address you want to sign the message with (should be populated by default, type it otherwise)
    - Signature is generated from your message and the address' private key.
    Note: Any changes to the message will invalidate the signature. If you want to modify the message you will have to generate a new signature.


That's it you can now send the message, the address and the signature to whoever requested it. It is safe to do so as it does not contain any private key or sensitive information that could give access to your wallet.

Useful tool: You can verify the message / signature here: https://tools.bitcoin.com/verify-message/

That's it.

I hope it helps.


** Disclaimer: I provide the information above as-is without any guarantee **

Hi All,

You are here because you need to export Bitcoin private keys from a Blockchain wallet.

Before reading the rest of that message make sure you understand the concepts of wallet, address & private key (there are plenty of useful resources on that forum).
Moreover ask yourself what you want to do with that private key!
The private key gives full access to your address and therefore to your funds.
Keep it secret and never give it to anyone! ANYONE!!

Ok let's get started...

The Blockchain wallet is very easy to use and a like an exchange it allows users store, buy and sell Bitcoins without any technical knowledge.
That's great for most people and most cases but with simplicity and "user-friendliness" come the inability to access advanced features/options.
That's what's happening with the default wallet of the Blockchain wallet. Its addresses are bound to the wallet and cannot be used individually anywhere else without exporting the whole wallet with a third party tool.

I - Exporting the private key of an imported address
It is very straightforward and available through the user interface.
  1. Log on to your wallet
  2. Click on "Settings > Addresses"
  3. Find the address you want to export
  4. Click on "More options > Private key"
  5. Click on "confirm" in the warning window
  6. You should now be able to copy the private key

Here is a screenshot to summarize the steps above:



II - Exporting addresses from the default wallet
As explained above the challenge is to export the private key of an address from the default wallet as they are bound to the wallet.

Here is how to do so:

  1. Make sure you have your seed phrase available (the 12-word phrase generated when you created your wallet)
      Consider the seed phrase as precious and sensitive as a private key as it give full access to you wallet! Again keep it secret and never give it to anyone!
  2. To extract information from your wallet you will need to use the following GitHub project: https://github.com/iancoleman/bip39
  3. Download the file called "bip39-standalone.html" (click on it, then click on the "Download button" and save the file)
  4. Open that html file locally (does not seem to work with IE). It works offline if you are more comfortable manipulating your wallet offline.
  5. Change the number of words to 12
  6. Input your seed phrase in the fields called "BIP39 Mnemonic"
  7. Finally scroll down to the section called "Derived addresses", spot the address you are interested in and copy its private key


That's it.

I hope it helps.

Refs / Credits:
- https://github.com/iancoleman/bip39

** Disclaimer: I provide the information above as-is without any guarantee **

Done.
Good luck everyone.

https://twitter.com/fglxrp

I know that's an old thread but thanks for clarifying.

Good luck with that project.

Well thought it seems promising. I will keep an eye on this project.

Looking forward to knowing more...