Bitcoin

Guide to Store your Bitcoins in a Multisignature Cold Storage Address

Please note, this is only for storing your bitcoins safely offline. It is not a guide to having a secure offline wallet for everyday use.

Also note, there is a million other ways to store your coins offline – I am sure some will be suggested in the comments, however this guide is aimed at simplicity, ease of use and paranoia of loosing coins. However, there are more secure ways of generating private keys than used in this guide, but I think most will agree the method used here is very, very safe.


Ever since I got a few coins I’ve been wanting to secure them properly offline, but haven’t gotten around to it before now. I made this guide because I know it would have helped me, so hopefully it can help someone else sparing some time or even better securing their coins in a safer way.

This guide is intended for the new user, explaining every step thouroughly in the process. It does not involve using specialized software such as Armory or Electrum, however it requires a certain amount of technical know-how (such as changing settings in the bios of a computer).


I HIGHLY SUGGEST TESTING THE METHOD BY COMPLETING THE GUIDE WITH A SMALL AMOUT FIRST. ONLY THEN, REPEAT THE PROCESS WHEN YOU FEEL CERTAIN YOU KNOW AND UNDERSTAND, WHAT YOU ARE DOING.


WHAT THIS GUIDE WILL DO

Create a multisignature M-of-N Shamirs Sharing Secret address to which you will send the coins you want to store. Store the private keys on printed paper and on USB sticks, ready to be distributed to people you trust, bank deposit boxes or something similar.

This is done through an offline Linux invironment, using well known open source software to generate the private keys.


WHAT YOU NEED

  • Bitcoins ready to send to the cold storage address. This could be on an exchange (i.e. Bitstamp), in a hot wallet (i.e. Blockchain) or elsewhere.
  • A(n old) computer. For maximum security (paranoia) a computer that has never been connected to the internet.
  • An online computer.
  • Three or four USB sticks. Brand new or formatted.
  • A printer that can connect to the computer by cable.

STEP BY STEP GUIDE

ON YOUR ONLINE COMPUTER

1. Download Linux Mint .iso file by going to this webpage and click on a proxy near you. (Please note, if your offline computer is a 32bit system, you need to go here instead)

2. Download Universal USB Installer by clicking this link.

3. Insert a USB stick in your computer and run the program Universal USB Installer. Select Linux Mint, the iso file you downloaded in 1. and the flash drive in each of the drop down menus.

ON YOUR OFFLINE (OLD) OFFLINE COMPUTER

4. Get into the bios. If possible, disable all wifi. Set boot priority to USB before disk storage.

5. Insert the USB stick you made in 3 and boot the machine in Linux Mint.

6. On the desktop is a file that reads “Install Linux Mint”. Double click. Choose to erase the disk and install Linux Mint. When prompted, select the “Overwrite free disk space” option. (Can’t remember if that’s the exact wording).

7. Pull out the USB and reboot in Linux Mint from the Hard Drive.

ON YOUR ONLINE COMPUTER

8. Insert the USB stick and format it.

9. Download www.bitaddress.org by clicking this link.

10. Extract the folder and copy it to the USB stick.

ON YOUR OFFLINE (OLD) OFFLINE COMPUTER

11. Insert the USB stick and run the file bitaddress.org.html

12. Move the mouse around until you see the menu tabs. Go to the Split Wallet tab

13. Select the number of shares you want to distribute and the amount of keys needed to re-create the private key. I did 4 and 2 – that way I hold two shares in separate locations and gave the last two to different family members.

14. Shrink the Firefox window so only share1 is visible. Hit Alt + Print Screen and save the screendump to the desktop.

15. Repeat this for the other shares as well as the address.

16. Connect the printer to the computer and install it though the Start -> Printers menu (works 99% as in Windows).

17. Print each screendump to seperate peaces of paper.

18. Insert a new USB stick and copy the bitaddress.org-master folder and the share1 screendump to the USB stick.

19. Do the same for the amount of shares you have on separate USB sticks.

20. Laminate the shit out of each paper.

21. Insert the USB stick you made in step 3. and boot the computer.

22. Repeat step 6. This will format the offline computer once again removing the information of all the shares.

23. Now you have a set of each share comtaining a paper print and an image on a USB stick. Distribute the set of shares in various locations that you can trust.

24. Send your bitcoins to the Address the way you prefer. From an exchange, a hot wallet or something else.


WHEN YOU NEED THE COINS AGAIN

When you need the funds, simply go to the “Split Wallet” tab on bitaddress.org on your offline computer and insert the shares in the bottom white space separated and generate the private key. This can then be used to sweep or import to your preferred bitcoin wallet service in the future.

Guide by lolhat