Bitcoin Forum

I am not very tech-savvy, so please excuse me for asking what may seem like a very tiresome question for most of you, but I would like to know if splitting my hard drive between Mac and Windows would be an effective way to keep my bitcoin wallet offline. It seems like it should work just as well as storing my wallet offline on an entirely seperate computer, right?

You'll likely find many definitions of "cold storage".

Here is the definition I use:
   - storage of bitcoins using bitcoin addresses that have never been on any computer connected to a network.

So it all depends on your risk profile and what you're trying to accomplish.

For me, I did the following:
   a) re-image a blank mac laptop.  disable its network capability.  verify that the image matches Apple's.
   b) encrypt the hard drive
   c) manually load software (via USB) for creating a bitcoin address.  I built this from scratch; verifying the source code signatures.
   d) extract the public keys of that address only.
   e) send coins to your public keys from anywhere.  They're cold.
   f) finally, I made a couple of encrypted USB sticks with my private keys and keep them as backups.

I'm open to feedback on this approach.

I believe Armory claims to do some form of cold storage for you too.

Hope this helps,
Mike


 

You can also print off paper wallets and keep it safe. I prefer this type of paper wallet as it is not only aesthetically pleasing and looks like paper money, but it also has a secure 3-fold piece to keep your private key safe. I would recommend using a laser printer than an inkjet printer as the quality is not only higher, but inkjet ink can run off if wet.

https://bitcoinpaperwallet.com/

Ideally you would want to keep your paper wallets in a fire proof safe or deed box which has protection against water and fire. The paper wallets have private and public keys which you only need the public key to send a deposit to your wallet. When you want to spend bitcoins, use your private key. The advice that the paper wallet sites say is that once you extract the private key, you must take out all your bitcoins from that wallet as it might be in danger of someone else using it. Personally, I distribute my bitcoins across many wallets so if something happens to one, my losses are minimized; you dictate what that paper wallet is worth.

There is also the hardware version which is a USB bitcoin wallet called Trezor. It is available for pre-order for 1BTC for the plastic version and 3BTC for the metal case version. Personally, I would wait until the cost of such device goes down and manufacturing processes mature.

HI,

I was just wondering if those paper wallet you talked about can be used for others alt currency like litecoin, worldcoin and etc?

If you find a service providing such feature then yes, I guess.

Anyone knows if its possible to have the private key on the paper wallet encrypted? Ideally also the public key.
I dont really like the idea of paper wallets if anyone who finds/steals one can claim the bitcoins.

You can add that extra layer of security, but in doing so, you would be adding an extra hurdle if you want to spend your BTC. Currently there is no service that I know of that can do it "automagically", you would have to do it manually for every wallet you produce.

There must be services similar to the one I mentioned. Look at http://www.paperwalletprints.co.uk/ though it did timeout when I was trying to look at it.

An easy and effective way to store your coins can be found at https://safepaperwallet.com/ (https://safepaperwallet.com/).  You receive a kit with materials and instructions to make great looking paper wallets that can be safely stored away for decades. All you need is a printer, a usb stick and your computer. Each wallet has a backup stub that should be stored at a different location to recover from fire, flood or other disaster. The starter kit comes with a HTML file that you would load onto a safe, offline computer via USB. Then following the instructions, you should have your own secure paper wallets in no time. :)

I personally find it all useless.

There are two types of attacks targeted and non-targeted.
To be safe from non-targeted attack you need to use up-to-date Windows or some 'unpopular' OS, like MacOS ; ) .. basically just using common sense and using any modern updated OS will keep you safe from non-targeted attacks.

But almost nothing will keep you 100% safe from targeted attack with a hot soldering iron ; )

Marcus,

Encrypting private keys is possible. It is part of a proposed standard BIP0038. We will be implementing it the next version of the Safe Paper Wallet and Open Paper Wallet software.

I create a backup encrypted wallet and put on my usb. Cold storage?

Not really - USB drives are notoriously unreliable.

I would not trust a flash drive with money.

Encryption is easy. Key management and key retention is hard.

Neither would I trust a USB stick. Just use a good old fashioned safe!

Here's what I did.

I generated a private key using my own code (software script) and then make a public address from it using my own code.

No bitcoin wallet was used.

The private key I wrote on a 3x5 and put it inside a security envelope. It will be kept in my bank safe deposit box next time I have reason to go there.

The public address I have written down several places.

I can send coins to that address whenever I want and check the balance using blockinfo or whatever I want, and should I have reason to suspect my devices with software wallet(s) have been compromised, I can send all currency in those wallets to that address.

I can't spend from that address until I import it in a wallet, and it is not saved in any data files, I'll have to enter the key into a wallet.
Hence any bitcoin I send to that address is in cold storage and is not readily accessible. In the near future it will require picking up envelope from safety deposit box.

I actually made two envelopes, one I'll ask mom and dad to store in their safety deposit box. That increases the risk a little but it also means I can access it if I'm visiting them and suddenly need coins (I spend a lot of time down there).

To me, that's what cold storage means.

Cold storage is safest storage.

I don't trust banks :D

they can't do anything with it.  so until the banks stop allowing withdrawals, it's a perfectly acceptable place to keep a second backup.

They can't tamper with a safety deposit box without leaving some evidence, if you lose your key it is a pain the *** to deal with.

I suppose it is possible they could but it is highly doubtful a bank would risk its reputation and charter by tampering with customer deposit boxes without a court order.

Although I am new here, I recommend paper wallets and use them frequently

Yes, paper wallets are one of the finer aspects of bitcoin.

You can have the actual paper wallet in a secure location and keep feeding currency to it, it's like having access to store physical money in that secure location without constantly having to go there. And you can keep an eye on the balance too.

It's such a simple concept yet so powerful.