How Would This Procedure Be Performed? Transfer to Offline wallet

Question

I've read alot of questions before I posted this... What I want to do is take my wallet from blockchain.info that contains a few bitcoins, and "store" it offline, however I have some specific questions if anyone can help:

• I understand creating a paper wallet from blockchain.info's My Wallet. However, if I do this then won't any sensitive data still possibly be saved on their server(s), therefore rendering the paper wallet not completely secure?
• In a partial answer to my first question, they have a way to generate and offline bitcoin address and corresponding private key. So would it be best to do that, and then from blockchain.info's My Wallet should I then send all bitcoins to this new bitcoin address, effectively eliminating any wallet that is saved in my account on that site? If that is the case, then:
  • would I even need a wallet? If my "paper wallet" shows the bitcoin address and its' corresponding private key, then is that all I need to put in a safe? just the bitcoin address that I sent all coins to from my wallet, and then that addresses private key?
  • should I delete any backups of the previous wallet that originally had the coins that I sent to this newly created offline address?
  • should I then close/delete my entire account on blockchain.info?

Forgive me if I sound redundant, but I guess I'm wondering if all I need to do is a "transaction" from my online wallet to a newly created 'offline' bitcoin address? In 10 years, in order to access these coins, I ONLY need that new bitcoin address and its private key?

Answer 1

I need to do is a "transaction" from my online wallet to a newly created 'offline' bitcoin address? In 10 years, in order to access these coins, I ONLY need that new bitcoin address and its private key?

Yes.

You can use Blockchain's product or print off an single address page from http://Bitaddress.org. Send a transaction to the public key and safely store that piece of paper until you next need it. Be very careful, though, because if you lose that piece of paper, you will lose the coins associated with that address.

Answer 2

However, if I do this then won't any sensitive data still possibly be saved on their server(s), therefore rendering the paper wallet not completely secure

That's absolutely correct. They're generating the key for you, and promising that they're not keeping the key for later. In the case of Blockchain.info, I trust them at their word, but you can never be sure that their site hasn't been hacked, or that you're a victim of a man-in-the-middle attack. The safest way to generate keys is to do it yourself on an offline computer, encrypt them immediately, and keep them offline forever (either in printed or electronic form). That said, unless you're dealing with incredibly large sums of Bitcoin, I wouldn't worry about it.

If my "paper wallet" shows the bitcoin address and its corresponding private key, then is that all I need to put in a safe?

Yes. In fact, all you need is the private key. To prove this to yourself, make up a test address and visit bitaddress.org. On the Wallet Details tab, paste in the private key. Confirm that the page generates the address from the key. So all you really need is the private key. Nonetheless, it's nice to keep the address handy. You can send more funds to it, and you can easily check its balance, all without regenerating the private key (and in the process putting the private key on a computer where it might be stolen).

should I delete any backups of the previous wallet that originally had the coins that I sent to this newly created offline address

I wouldn't. There is only downside. Suppose you delete your wallet and then realize you deleted the wrong one. Or in the process of emptying your trash can, you also deleted your term paper due tomorrow. Or you accidentally send money to one of the addresses in that wallet (which might happen because you put those addresses in your Bitcoin address book, or a friend had that address and tried to settle your $1,000,000 debt by sending Bitcoin to it). If you understand that having a private key is merely the ability to unforgeably sign a transfer from the signing address to another, then you understand that keeping private keys is power you want to have. And in the case where the corresponding addresses have a zero balance, there's no risk to keeping that power -- if someone obtained your old wallet, they'd find no Bitcoin at the addresses to steal.

Just make sure the old wallet is encrypted with a strong passphrase and offline, and there isn't any risk to keeping it.

should I then close/delete my entire account on blockchain.info

See above. If you don't trust them and worry they kept your private keys, then maybe deleting will help. Then again, if you don't trust them, why would they truly delete your account? They'd just hide it from you and claim to have deleted it.