I am guessing that many people who own Bitcoin in an Exchange are wondering what to do with their Bitcoins as we approach the various changes that are happening to Bitcoin. I don't profess to fully understand all the changes myself but I have read that Bitcoin could split and there is the potential for losing your coins if they remain on an Exchange. As a disclaimer, I am not making any comments with regards to this and you must decide yourself what you should do after being fully informed of all the risks.
Anyway, having said all of that there appears to be a lot of experts advising that you should remove your coins from the Exchange and deposit them into an offline wallet that you have control of. I am not going to go into the technical reasons as to why you should do this but I am going to tell you how I did this in what I believe was a secure and safe method. If you decide to move your coins to an offline wallet then I hope this is helpful to you. I would also like to point out that while having control of your Bitcoins may be the preferred option for many it does not come without risk. You really do need to know what you are doing to avoid losing your Bitcoins should you lose your key or passphrase or fail to keep a secure backup. Unfortunately, all the Exchange distrusters out there fail to emphasise this when advising to never leave your money in an Exchange. While Exchanges have a risk of being hacked they also do provide a relatively simple and secure way to hold your funds.
Before we go into the details on how to make your PDF version of a paper wallet and storing it securely I will let you know a little about myself. I find Bitcoins fascinating and have been following the technology for the past few years. I first heard about Bitcoin in the early days and considered mining it but unfortunately put my computing power into searching for little green men instead. I do own some Bitcoins and believe this technology is the way of the future. Having dabbled in crypto mining of Litecoin and Ethereum I have managed to learn many of the basic concepts of cryptos in general. While I would not pretend to understand the intricacies of Blockchain technology I have worked in the field of computer forensics for the past 20 years and believe my guide will help you create a secure wallet for your Bitcoin without the fear of your funds being compromised.
Anyway, moving along this is how I look after my own Bitcoins and you can follow this at your own risk. However, I do believe this is a secure way to hold your Bitcoins off line with virtually no risk of being hacked or losing your Bitcoins.
I use a paper wallet (sort of) which I store in an encrypted container. As long as I do not lose my password to the container no one can ever get my funds. If I lose or forget my password then that also includes me! Now there are many advantages to my method, the main ones being that I can have as many backups as I want and I don't care if I lose them as they are useless without the key and you can keep adding funds through the public address as many times as you want. Just remember however as with any paper wallet that you must cash your funds all at once in order not to risk losing them. Also, please ensure you fully understand how to cash in your paper wallet when you are ready to do so as I do not cover this in this paper. I believe that the process described below is better than printing and keeping the paper wallet in physical form because paper wallets can deteriorate over time and need to be stored securely as they can be stolen.
Ok let’s go, here are my detailed instructions:
Try to find an old laptop or computer that you can keep off your home network and the Internet. Unless you are 100 percent confident your system is clean conduct a fresh install of Windows 10 to ensure that there is no malware or nasties sitting in the operating system or other installed software. Do this totally offline while not connected to your network or the Internet. Ensure you have Adobe Acrobat Reader installed.
On another computer that is connected to the internet go to www.bitcoinpaperwallet.com. You can use any paper wallet generator but I like this one as I know it works and I have successfully deposited and withdrawn Bitcoin from it. It can also print an attractive paper wallet if you want. However, we are not going to be printing anything as we want to remain as secure as possible.
Click on the link "Generate keys and Print Paper Wallets". At the next page just click the "Skip" button as you are not going to be generating any wallets while connected to the internet. At the next page click on the link "Secure Download - GitHub zip file". Once at the download page download the "generate wallet-html" file. Once you download this file transfer it via a USB stick onto your laptop or other computer that is not connected to any network - that means that it is totally isolated from anything that could compromise the keys that you want to generate.
Unzip the file on your isolated and sterile computer and double click the HTML file. Now simply follow the instructions to generate your paper wallet. Once generated print the wallet to PDF only. You will only need to create a PDF of the front side of the wallet. This PDF file is now your secure paper wallet. You are not finished yet as we are going to enclose this in an encrypted container which you can then store anywhere with safety. We are also going to clean up the isolated computer to ensure the computer can never be compromised. Also, do not attempt to encrypt the wallet as this will only complicate cashing it in later and there is no need to as we are going to save it in an encrypted container.
Do not attempt to print the PDF paper wallet file as you will produce spool files on the computer and potentially have copies left on your printer. Do not copy the PDF file to another computer. Never open the PDF file on another computer as again you may generate cached copies and lose control of your secure private key to your Bitcoin.
Ok so I think you see where we are at now. You should have one copy of the PDF file on the isolated computer. Open the PDF file (on the isolated computer) to make sure you can clearly read both the public and private keys to your wallet. Ensure that nobody can see your private key as one simple photo of this could compromise your funds.
Once you are happy that you have a secure and readable wallet take a copy of the public key only and save that somewhere else so you can deposit your funds to. Close the PDF file.
Ok now download a copy of TrueCrypt version 7.1 a from the Internet. There are many sites that will have this but just make sure the site is reputable. Don't download the latest version from the official TrueCrypt site as this will no longer work. Also, don't worry about the claims that TrueCrypt is not secure as it has now been independently verified more than any other encryption program out there. If you are still not comfortable to use TrueCrypt feel free to use another software. However, remember that TrueCrypt is so widely used now you will always be able to get at your data provided you have your password.
Install TrueCrypt on the isolated computer where the PDF paper wallet is located. Make sure you transfer the installation file via USB and not through connecting the isolated computer to the any network. Once you install TrueCrypt follow these instructions to create a secure container. First click the menu item “Volumes” and then “Create New Volume”. You then want to select the default which is “Create an encrypted file container”. Click “Next” and then select “Standard TrueCrypt Volume”. You then select “Next” and then when you get to “Volume Location” select “Select File”. This is where you give your container a filename which you can call what you want. You then save the file. This will be the container where you keep your PDF paper wallet secure. Just follow the remaining instructions that TrueCrypt gives you including setting the password. The file size only needs to be a few megabytes in size. Keep it small so it is easy to copy and save in different places. It only needs to be large enough to host the PDF file. Ensure you use a strong password. I would recommend a password made up of several words containing upper and lower cases separated by symbols or numbers. The reason is that these are extremely secure but also easy to remember. For example "County&Pacific£cROCODILES;EAT-grass". Now it is up to you to decide on whether or not you want to write this down and keep it secure or just memorise it. If you decide to just memorise it DON’T FORGET IT! or you will not be able to access your private key to your Bitcoin.
Once you have created the container mount the container file within Truecrypt using the password phrase generated. To do this open TrueCrypt and on the first screen click “Select File” Point to the container file that you previously created and click “Open”. Then select a drive letter you want to give it. Make sure it does not clash with any existing drive letters. Then click “Mount”. You will be prompted for the password. Enter the password and click “Ok”. Provided you entered the correct password the file will open as a new drive on your computer. Now copy your PDF paper wallet to the container. Once copied dismount the drive by selecting “Dismount”. Mount and dismount the container a couple of times to make sure it works OK. Make sure you always dismount the container correctly in the Truecrypt software as they can easily corrupt. Don't worry however as you can take as many backups of this container as you want just in case you do end up corrupting it. It also does not matter how many copies you make or leave around on USB sticks or computers as they are completely secure without the password. Obviously do not leave the container mounted anywhere.
Once you are satisfied you have created the container and have copied the PDF paper wallet to the container then you can copy the container to another computer and make your backups.
Important note - once you mount the container file in TrueCrypt on a computer connected to the Internet your information is vulnerable so only do this when offline and are sure the computer is clean of all threats (malware etc). Avoid opening the PDF unless necessary as this could generate copies of your private key on the computer in various hidden locations on your file system and may not be easy to erase. You should not open the PDF paper wallet again or mount the container until you intend to cash the contents and need to access the private key.
Finally, you should clean up the isolated computer that you used to make your PDF paper wallet. To do this, you should do a forensic wipe of the entire hard drive. Now this might sound over the top but if anyone should get hold of this computer they could use specialised software to recover the PDF paper wallet file or any of the HTML files generated in the process. You could have 10's of thousands or hundreds of thousands of dollars sitting in this PDF paper wallet so why take any risks? There are many utilities you can use to do a full disk wipe. Acronis True Image is great and not too expensive. There are many free ones too but you may have to test them. If you can get your hands on something like Encase then that is even better. Also, don't just think you can format the drive as this will NOT wipe it.
Good luck and I hope this article helps. I welcome any feedback on this process or suggestions for improvement. Always try anything new with a small amount of Bitcoin first. And remember everything you do with Bitcoin is done at your own risk – but that’s what makes it all fun!