Bitcoin Forum

There are other ways to achieve the same thing, like using python to convert a random seed to an xprv, then use a fixed derivation path to derive private keys from this xprv, then use the private key to generate a public key, and the public key to generate an address...

priv = sha256('ultrasecure password phrase')

pub = privtopub(priv)
addr= pubtoaddr(pub)

2) disconnect your internet, start electrum, create a new wallet, write down the seed words, generate a new deposit address
~
4) delete the wallet again, reboot, reconnect to the internet, fund the address generated in step 2 (and 3, since that's the same address)

2) Also, is another method to write down the private key and public keys on paper? If so, how are these obtained and then how are they input back into Bitcoin.qt?

Click Help > Debug window > Console > enter importprivkey "privkey" ( "label" ) ( rescan )

Importing private keys into Bitcoin Core is easy:

enter importprivkey "privkey" ( "label" ) ( rescan )

--snip--
Is it actually

importprivkey xxxxxxxxxx mybitcoinsatDec2017 rescan                          where xxxxxxxxxx is the private key and is "label" just a name for reference? What does (rescan) do and do I type it without the brackets?
--snip--

One more question.
I bought and sold Bitcoins using a previous computer and I encrypted that Bitcoin-qt wallet.
I have just built a new computer, installed Bitcoin-qt 15.1 and downloaded the blockchain. Very pleased as it only took about 8 hours.  :o)
What happens now when I swap the default wallet.dat (that shows zeros) with my actual wallet.dat that holds all my Bitcoins.
Is the encryption in my wallet.dat file?
Or do I load my wallet.dat file and then encrypt the new Bitcoin-qt wallet, and if so can I use a different password?

importprivkey xxxxxxxxxx mybitcoinsatDec2017 rescan                          where xxxxxxxxxx is the private key and is "label" just a name for reference? What does (rescan) do and do I type it without the brackets?

Where do you find this information?

So do I just need the private key to reclaim my bitcoins. Are the public keys generated from the private key?

Also, in the bottom right of Bitcoin-qt is a button labelled HD. What does that do?

Thanks for you help. I'm on the verge of understanding this fully

I bought and sold Bitcoins using a previous computer and I encrypted that Bitcoin-qt wallet.
I have just built a new computer, installed Bitcoin-qt 15.1 and downloaded the blockchain. Very pleased as it only took about 8 hours.  :o)
What happens now when I swap the default wallet.dat (that shows zeros) with my actual wallet.dat that holds all my Bitcoins.
Is the encryption in my wallet.dat file?

Or do I load my wallet.dat file and then encrypt the new Bitcoin-qt wallet, and if so can I use a different password?

I bought and sold Bitcoins using a previous computer and I encrypted that Bitcoin-qt wallet.
I have just built a new computer, installed Bitcoin-qt 15.1 and downloaded the blockchain. Very pleased as it only took about 8 hours.  :o)
What happens now when I swap the default wallet.dat (that shows zeros) with my actual wallet.dat that holds all my Bitcoins.
Is the encryption in my wallet.dat file?

Or do I load my wallet.dat file and then encrypt the new Bitcoin-qt wallet, and if so can I use a different password?

If I load my bitcoin loaded wallet.dat file into the newly installed Bitcoin-qt, because you say the encryption is in my wallet.dat file, will the option to encrypt be greyed-out? (I'm not experimenting or doing anything until I fully understand).

I thought the idea of the encryption is to password protect the wallet.dat file? If the encryption is in the bitcoin loaded wallet.dat file, then if someone else gets hold of my file, the encryption protection would be meaningless?

When the bitcoin loaded wallet.dat is loaded into the newly installed bitcoin-qt, will I be able to transact straight away, ie, move bitcoins to my exchange, or do I at some stage enter the encryption password?

I was keen on preparing a paper wallet but frightened off as I'm reading that if loaded using the private key, and then spending a part of the total, my wallet becomes empty.

I think the easiest thing to do now is just make multiple copies of my wallet.dat file, on usb sticks and CD's. I read that USB's and any flash card may not be reliable long term. I would have thought CD copies will be reliable long term.

It works exactly the same as it does now: you make a transaction, and enter the password before sending.

You can easily do that by sending it entirely to your own wallet (this is called swiping, very easy if you use a mobile wallet and QR-code

Can I test the password somehow, instead of actually sending Bitcoins anywhere?

walletpassphrase YOURPASSPHRASE 0

How do I put a small amount on a paper wallet?

3) Updated backups on SD cards and DVD disks so to keep them 'active'. I'm told cards can age and files get corrupted. I'm thinking DVDs should have a reasonable life.

Flash may indeed deteriorate after a few years but also DVDs aren't immune. But with quality media, for example Verbatim, I'd put my bets on DVDs being more likely to be OK after 10 years.

May I take advantage by asking if anyone can supply a web site address that tells me how I benefit from Bitcoin cash?
For example, if I want to sell one bitcoin, how do I get the bitcoin cash value as well?

BTW, can someone find my IP address from comments on the internet regarding Bitcoins and trace back to my computer? I'm asking questions on a couple of forums/ comments pages and I hope it doesn't give a crook some ideas.

Further. I have been looking at ways to make a paper wallet by printing my private and public keys.
The instructions I have found say I have to transfer my Bitcoins to the paper wallet. How do I do that? If I transfer them to my paper wallet, does that make my wallet.dat file useless? I want to keep my wallet.dat file intact so it still shows my bitcoins when I fire-up Bitcoin-qt, but also have the paper wallet as a further back-up.

Flash may indeed deteriorate after a few years but also DVDs aren't immune. But with quality media, for example Verbatim, I'd put my bets on DVDs being more likely to be OK after 10 years.

If you want to look further into that, there's also the M-Disc disc variants, which claim to be more durable than "normal" discs.
Also, I think in general Bluray (not LTH) might be more durable than DVD.

Storage media are not necessary or optimal for less than some thousands of characters.
Get an old manual typewriter and some high quality paper.

1) walletpassphrase YOURPASSPHRASE 10. This I beleive unlocks the wallet for 10 seconds.

2) During the 10 seconds, type dumpprivkey. Does this leave the bitcoins intact in Bitcoin-QT wallet? Does this dump a file showing all the private and public keys. If so, what is this file called and its extension?

3) Use importprivkey to import private keys back into Bitcoin-QT. If so, what is the procedure.

4) What does importmulti do? Is this relevant?

5) If this works, is there still a problem that if some bitcoins are sold, the 'change' bitcoins are still lost?

I've tried to give feedback/answer the 5 questions:

correct

Ye-esss

Bitcoins aren't something physical, they are not stored on your pc. If you "own" bitcoins, it basically means you have access to the private key that can be used to create a signature for one or more unspent outputs that funded the address that was created by hashing the public key belonging to the private key in question.
In very simple wording: your bitcoins are just lines in blocks that are stored on thousands of computers. Importing or exporting private keys doesn't change anything (unless you use an unsafe procedure/PC and your private keys get exposed, in this case you might get robbed)
So, dumping the private key will not "destroy" your bitcoins.
dumpprivkey only dumps one private key to stdout. If you need to dump all private keys, you can use dumpwallet (dumpwallet actually takes a parameters in which you can define the file that will be used to dump all keys to)
OK, I understand that the Bitcoins are just computer code. So if I use dumpwallet, what file will be created? Can this be read as a text file? Is that how it is done? I have a number of bitcoins in Bitcoin-qt.
 Will these just have the one private key?


open the debug window => importprivkey --privatekey--
This procedure will rescan the blocks on your disk, importprivkey takes an optional argument that will avoid this rescan (if you want to)
So do I copy the private key from the dumped text file and type

importprivkey --privatekey-- with the private key typed between --  and --? I know some of these symbols are instructions and not actually typed, but do I type the -- and --?.



I've never used this, but apparently it's used to import multiple private keys at once

I have a hard time understanding this question. IF you use a decent wallet, it will guide you trough the process of creating a transaction spending one or more of the unspent outputs controlled by you. A decent wallet will make sure it funds the address of whoever you're sending BTC to, and it will make sure the change is being used to fund a change address.
Only if you manually create a raw transaction, or if you use a newbie-unfriendly, bad, wallet, or if you start messing with options you don't understand, you might end up losing your funds.

So, I'm using Bitcoin-qt. If I import the private key, my bitcoin total will show-up, yes, and then I could, for example, send one bitcoin to my exchange and the remainder will still show in Bitcoin-qt for another time?

You don't get the BCH value when you sell BTC... you get the BCH by having had BTC on a private key when the fork happened... it doesn't matter what you do withe BTC "after" the fork has happened... the BCH will stay with the private key... you get your BCH by importing your BTC private key (or BTC wallet file) into a BCH wallet (like BitcoinABC or ElectronCash).

OK, I understand that the Bitcoins are just computer code. So if I use dumpwallet, what file will be created? Can this be read as a text file? Is that how it is done? I have a number of bitcoins in Bitcoin-qt. Will these just have the one private key?

So do I copy the private key from the dumped text file and type

importprivkey --privatekey-- with the private key typed between --  and --? I know some of these symbols are instructions and not actually typed, but do I type the -- and --?.

So, I'm using Bitcoin-qt. If I import the private key, my bitcoin total will show-up, yes, and then I could, for example, send one bitcoin to my exchange and the remainder will still show in Bitcoin-qt for another time?

BTW, when typing-in instructions to the console page, I don't see an activation device, like a button. Is it ok to just highlight the code and hit Enter?
Also BTW, many, many thanks for the help. I don't understand all the terminology so have to take this to grass-roots level. You see, what is a 'raw transaction'? And 'by hashing the public key belonging to the private key in question@ is beyond my understanding.
Bitcoins seems to have terminology all of it's own from what I have seen all over the net.

So, say I sell 1 BTC. If I then use the wallet.dat file with BitcoinABC, will the equivalent BCH still be available?

The only way I can see this working is if the BTC and BCH details are now both in the wallet.dat file. Is this the case? Presumably it would be a useful upgrade to Bitcoin-QT if it would show and allow transactions for both BTC and BCH.

So, say I sell 1 BTC. If I then use the wallet.dat file with BitcoinABC, will the equivalent BCH still be available?

The only way I can see this working is if the BTC and BCH details are now both in the wallet.dat file. Is this the case?

Presumably it would be a useful upgrade to Bitcoin-QT if it would show and allow transactions for both BTC and BCH.