Bitcoin Forum

Other => Beginners & Help => Topic started by: Bizmark13 on February 26, 2014, 11:50:49 AM



Title: Is the private key really all that I need?
Post by: Bizmark13 on February 26, 2014, 11:50:49 AM
If I had 100 bitcoins in my wallet and my hard drive was irreversibly destroyed (eg. in a fire), but I managed to write the private key on a piece of paper elsewhere, would I be able to gain access to my 100 bitcoins?

An example private key I found on the bitcoin wiki is something like this:

5Kb8kLf9zgWQnogidDA76MzPL6TsZZY36hWXMssSzNydYXYB9KF

And if so, then why is the process of creating a paper wallet much more complex than just writing down the private key? The bitcoin wiki suggests downloading and booting from a live CD for example and all of the paper wallets that I've seen have additional information on them like QR codes and the wallet address even though the bitcoin wiki says that a wallet address can be generated from a private key anyway (but importantly, not the other way round).

Also, if someone is using something like the Electrum wallet then are there any differences?


Title: Re: Is the private key really all that I need?
Post by: BlockChainLottery on February 26, 2014, 12:03:37 PM
The only thing needed to recover your funds is the private key. So yes, you would have your 100BTC back.
All the other stuff like booting from a live CD are just precautions to prevent others stealing your private key.


Title: Re: Is the private key really all that I need?
Post by: BlockChainLottery on February 26, 2014, 12:06:53 PM
...

Also, if someone is using something like the Electrum wallet then are there any differences?

Electrum's private keys are generated from a seed. Then you can get back your funds if you got that seed or the derived private key.


Title: Re: Is the private key really all that I need?
Post by: Automatic on February 26, 2014, 12:09:59 PM
Yes, that's all you'd need, but, here's the thing that catches most people because they don't realize how Bitcoins work, first of all, a tl;dr, "When you spend any amount of money, the money will probably no longer be in the same address".

Longer version:-
It's impossible to spend less than the amount you received in a previous transaction, but, obviously, the majority of the time you won't want to spend the exact amount of a TXIN (or multiple ones combined), so, what do you do? You send the amount you want to spend to the receiver, then, you send the remainder ('change') back to yourself, normally, on a different address, meaning the private key for the last address is now worthless.

Personally, I recommend Armory (Or any other client that uses a pre-saved seed to generate keys), as, it fights this by using a seed which you print off to generate all addresses, this means even if you receive money on an address after paying, or, send change to a new address, that printed wallet two-line long string still saves all your funds.

EDIT:- I'd just like to point out I've never used Electrum, so, if Electrum also used a pre-saved seed, just back that up (And any other required info) and you're good. This is what the Armory .pdf (you print) looks like:-
https://i.imgur.com/fLv2WUH.png


Title: Re: Is the private key really all that I need?
Post by: Bizmark13 on February 26, 2014, 12:30:17 PM
The only thing needed to recover your funds is the private key. So yes, you would have your 100BTC back.
All the other stuff like booting from a live CD are just precautions to prevent others stealing your private key.


Oh, I see. So in order to make a paper wallet backup the secure way, I would:

1. Remove my computer's hard drive
2. Boot from a live CD
3. Connect to the Internet
4. Download a program that generates private keys offline
5. Disconnect the Internet
6. Use the program to generate a wallet address and a private key which I write down
7. Turn computer off and put hard drive back in
8. Turn computer back on and transfer coins to the new wallet address

Is this correct?


Title: Re: Is the private key really all that I need?
Post by: BlockChainLottery on February 26, 2014, 12:55:24 PM
I have never done it like that, but if it's somehow possible it would be one of the most save ways to do it.
I'm sure if you search this forum, there will be a ton of tutorials to make paper wallets.
They will warn you for even the most less probable ways to get your keys stolen.
I think some of the safety measures are too extreme, but you never can be too sure.
It's is your own responsibility after all.


Title: Re: Is the private key really all that I need?
Post by: bytesnpieces on February 26, 2014, 01:07:03 PM
Yes that is correct, the private key is all you need to get those coins, so keep it safe ;)


Title: Re: Is the private key really all that I need?
Post by: Bizmark13 on February 26, 2014, 01:38:35 PM
...

Also, if someone is using something like the Electrum wallet then are there any differences?

Electrum's private keys are generated from a seed. Then you can get back your funds if you got that seed or the derived private key.

Yes, that's all you'd need, but, here's the thing that catches most people because they don't realize how Bitcoins work, first of all, a tl;dr, "When you spend any amount of money, the money will probably no longer be in the same address".

Longer version:-
It's impossible to spend less than the amount you received in a previous transaction, but, obviously, the majority of the time you won't want to spend the exact amount of a TXIN (or multiple ones combined), so, what do you do? You send the amount you want to spend to the receiver, then, you send the remainder ('change') back to yourself, normally, on a different address, meaning the private key for the last address is now worthless.

Personally, I recommend Armory (Or any other client that uses a pre-saved seed to generate keys), as, it fights this by using a seed which you print off to generate all addresses, this means even if you receive money on an address after paying, or, send change to a new address, that printed wallet two-line long string still saves all your funds.

EDIT:- I'd just like to point out I've never used Electrum, so, if Electrum also used a pre-saved seed, just back that up (And any other required info) and you're good. This is what the Armory .pdf (you print) looks like:-

OK, well thanks for the info. I'm using Electrum so I'll probably be doing this then.


Title: Re: Is the private key really all that I need?
Post by: TrailingComet on February 26, 2014, 04:35:48 PM
Absolutely correct, so keep the prvt key safe