Bitcoin watch only wallet
This document shows how to create an offline wallet that holds your Bitcoins and a watching-only online wallet that is used to view its history and to create transactions that have to be signed with the offline wallet before being broadcast on the online one.
Create an offline wallet
Create a wallet on an offline machine, as per the usual process (file -> new) etc.
After creating the wallet, go to Wallet -> Master Public Keys.
The Master Public Key of your wallet is the string shown in this popup window. Transfer that key to your online machine somehow.
Create a watching-only version of your wallet
On your online machine, open up Electrum and select File -> New/Restore. Enter a name for the wallet and select “Restore a wallet or import keys”.
Paste your master public key in the box.
Click Next to complete the creation of your wallet. When you’re done, you should see a popup informing you that you are opening a watching-only wallet.
Then you should see the transaction history of your cold wallet.
Create an unsigned transaction
Go to the “send” tab on your online watching-only wallet, input the transaction data and press “Send...”. A window opens up, informing you that a transaction fee will be added. Continue.
In the window that opens up, press “save” and save the transaction file somewhere on your computer. Close the window and transfer the transaction file to your offline machine (e.g. with a usb stick).
Get your transaction signed
On your offline wallet, select Tools -> Load transaction -> From file in the menu and select the transaction file created in the previous step.