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I started investing a not insignificant part of my salary into BTC a few years ago. I created 10 paper wallets (using bitcoinpaperwallet.com) on a dedicated laptop disconnected from the Internet. I then stored them in my office drawer however I no longer feel safe due to potential theft/elements etc. and I don't have access to a safety deposit box.

I want to digitize them and use strong encryption so I can store them on a few different servers that I own for redundancy. I don't need to regularly withdraw BTC from these wallets as they are for investment, I keep a separate small hot wallet on blockchain.info for spending. I'm confused as to how I should;

a) Digitize the paper wallets. I dont want to have to manually enter the private keys and make a mistake. Is there software I can run on the disconnected laptop that can scan the QR codes for the private keys using the webcam? I know blockchain.info does this but the laptop doesn't have Internet access. b) Once I have the private keys in a digital format (either in a plain text file or some wallet format) what form of encryption do you recommend. I'm currently planning on using PGP with 8k RSA keys.

Any advice would be most appreciated.

  • Something to think about: where do you keep the private keys (or passwords) to your encrypted digital files? To prevent the accidental loss of your coins, you should be certain that they won't be accidentally lost due to data failure, a human forgetting/dying, etc. A common way to do this (e.g. Armory and Electrum) is to have a paper backup (printed, handwritten, whatever) and keep it in a secure place. This is in essence another sort of paper wallet, so it has the issues you do now. I'd strongly consider a safe deposit box. A paltry sum compared to securing a large portion of a salary. – Tim S. Jun 23 '14 at 16:10
  • Can you clarify, when you say "I don't have access to a safety deposit box." that you don't currently own one, or (trustworthy ones, at least) aren't available in your locale? I'm considering writing an answer along the lines of "you're asking the wrong question", but it only applies if you can have some sort of secure storage for paper. – Tim S. Jun 23 '14 at 16:15
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    Thanks Tim. I'd memorize the passphrase and also spread parts of it into other encrypted vaults I use e.g. lastpass. When I do this I usually do something like reverse the order or chars or use a simple substitution cipher on it. I'll always need to remember something though but I feel I can handle that. When I said I don't have access, I'm a perpetual traveler working as a programmer in different parts of the world but never long enough to open local bank accounts. I don't want to store the paper somewhere that I need to constantly move. – user18343 Jun 23 '14 at 17:13
  • Why don't you encrypt, use steganography, and drop that into a few and free cloud drives? – YoMismo Sep 21 '15 at 9:08
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Not completely what you asked for, but if you have a significant amount of money in bitcoin it makes sense to store them on a hardware wallet like trezor, ledger, ... . These cost 100$ or less and are totally worth it for ease of use and peace of mind.

I would sweep the paper wallets with mycelium and send the btc to your hardware wallet. This completely eliminates the threat of your computer being infected/hacked/etc. Since you have 10 paper wallets, I'm presuming the individual amounts might be ok to store on your phone for a few minutes.

Regarding storage, all addresses on the hardware wallet are generated starting from a 24 word seed. So you could write down 2 or 3 copies of this seed and distribute them in vaults/to trusted people. These 24 words can of course also be encrypted etc. If your hardware wallet breaks, all bitcoins can be retrieved by using these 24 words and a new compatible hardware/software wallet.

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To read QRs, download this website and open it. It worked locally offline for me in Firefox. Chrome was a little harder because it blocks the webcam from file:/// urls. I got it to work with this but it requires python to be installed.

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If you have an android phone, you can use the bitcoin wallet app which now has a feature to sweep a paper wallet using the camera. Then you can back up the private key generated by the app and (if you want), delete the app. The mycelium app might also have this functionality.

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The safest way I think to go from a paper wallet -> digitalized one is to simply use a qr reading app on your phone to read the two codes. What happens when you read the QR codes is the public or private key (the one you are reading) will go to your clipboard.

Now you can use the private and public key to import your wallet. You have a couple options, the first one is to use a wallet provider such as blockchain.info However, if you do not trust such a provider you can use Multibit and run it on your computer. Multibit does require internet connection in order to synchronise so simply keeping your private and public key in an encrypted text file could suffice. I am not familiar with the best encryption for such a task but a safe way to get your keys into a digital format is to use your phone or a camera with a qr reader app.

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You might want to use a standized BIP 38 encrypted keys that can be natively imported into a few cell phone or tablet application wallets. Here are two JavaScipt implementations to look at. Others are likely to exist.

  1. Canton Becker
  2. Bitaddres.org
  3. Michael Mure

Cross correlate consistency of results between implementations before betting the bank. (Never really know if someone has hacked these open source Implementions unless you are a software geek.) Be sure to use very high entropy passwords and do a few full cycle checks in advance before sending funds to any new wallet addresses. Some of these application buttons are not as user friendly as you may think, and user errors could bite you.

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If you want to encrypt those keys, i would recommend using RSA-2048.
It is above military grade and will not be factorized in the near future (well, i'll take that as upcoming 15 years or so, who knows the computer technologies booms up?)

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