can i use bitcoin core as an offline (cold) wallet

[pooya87]

can i use bitcoin core as an offline (cold) wallet?

what i want to do is, i want to install bitcoin-QT on an offline pc and just use it to create an address and send my bitcoin there.
can i do this without need of blockchain?


also what should i do (later) if someday i want to spend these bitcoins? how can i send them without having to go online and download blockchain OR exporting private keys

[Dread Pirate Roberts]

 using wallet who never online in internet ( only for get address )
and visit unfamiliar website it will be safe

[Madness]

can i use bitcoin core as an offline (cold) wallet?

what i want to do is, i want to install bitcoin-QT on an offline pc and just use it to create an address and send my bitcoin there.
can i do this without need of blockchain?


also what should i do (later) if someday i want to spend these bitcoins? how can i send them without having to go online and download blockchain OR exporting private keys

It's not possible as far as I know mate .
EDIT : After searching a little bit , I found something that May be useful for you , check it out (look what the other members says ) : https://bitcointalk.org/index.php?topic=265738.0 also this Link from the Bitcoin wiki may help you too : https://en.bitcoin.it/wiki/How_to_set_up_a_secure_offline_savings_wallet . Good luck mate

~ Madness

[buysellbitcoin]

can i use bitcoin core as an offline (cold) wallet?

what i want to do is, i want to install bitcoin-QT on an offline pc and just use it to create an address and send my bitcoin there.
can i do this without need of blockchain?


also what should i do (later) if someday i want to spend these bitcoins? how can i send them without having to go online and download blockchain OR exporting private keys

I will suggest you to look into Multibit or Electrum, but if you want to use Bitcoin core only then you can follow below process :
1. Create offline walllet, generate address, encrypt it with strong passphrase. Note down your bitcoin address.
2. Store passphrase in somewhere else where you can recover it. If you lose passphrase you will loose your coins.
3. Take backup of encrypted wallet and store 2-3 copies somewhere. Dont store passphrase and wallet backup together.


Regards

[pooya87]

can i use bitcoin core as an offline (cold) wallet?

what i want to do is, i want to install bitcoin-QT on an offline pc and just use it to create an address and send my bitcoin there.
can i do this without need of blockchain?


also what should i do (later) if someday i want to spend these bitcoins? how can i send them without having to go online and download blockchain OR exporting private keys

It's not possible as far as I know mate .
EDIT : After searching a little bit , I found something that May be useful for you , check it out (look what the other members says ) : https://bitcointalk.org/index.php?topic=265738.0 also this Link from the Bitcoin wiki may help you too : https://en.bitcoin.it/wiki/How_to_set_up_a_secure_offline_savings_wallet . Good luck mate

~ Madness

the bitcointalk post was interesting but didn't apply to my situation. and the wiki link helped me thanks "How to Deposit Funds" and "How to Retrieve Funds" was useful

but i still want to know if there is a way to send bitcoin without having to import the wallet.dat into bitcoin-qt and going online with it?

[TookDk]

If you want a super easy and reasonable safe setup:

Use your offline computer to generate address with a downloaded version of Ninja's page (https://www.bitaddress.org/).
Print the page as pdf including the QR code for the private address, store locally on your offline computer (or just as txt, if you don't care about the QR).
(you can encrypt the pdf files with truecrypt if you want to add encryption).

When you need to spend coins, then open the pdf file on your offline, use mycelium (or other wallet that support camera) to capture the QR direct from the screen of your offline computer.
You can just make, lets say 10-20 offline wallets, and divide your funds on these, so you don't have to redeem all at once.

With this setup will your offline computer never be connected to the internet.
You really don't need to worry about malware, as long as you make sure that computer never go online.

If you don't trust the random generator in Ninja's page just use a dice to make a 99 digit base6 random number (bitaddress.org can convert this into a bitcoin addy).

The core of this method is to use bitaddress.org offline.

[sho_road_warrior]

can i use bitcoin core as an offline (cold) wallet?

Yes. You dont have to sync to create private keys and corresponding addresses. The next version even allows you to create import watch only addresses.

what i want to do is, i want to install bitcoin-QT on an offline pc and just use it to create an address and send my bitcoin there.
can i do this without need of blockchain?

Yes.

also what should i do (later) if someday i want to spend these bitcoins? how can i send them without having to go online and download blockchain OR exporting private keys

You would have to create a transaction by hand[1][2]. I highly suggest you try to create a raw transaction on the testnet before you try this with your actual coins. Bitcoin core/qt 0.10.0 will have an option to add "watch only" addresses, which will probably enable you to use listunspent on the online wallet. Besides that, if you understand how createrawtransaction work you can use any block explorer to get the information you need to create a transaction. Write the data by hand into your offline wallet and copy the signed transaction via a text file or by hand to your online wallet for broadcasting. The wallet does not have to be fully synced to broadcast a transaction AFAIK.

As others have pointed out, there are other wallets that are easier to use as an offline/online combi wallet.


[1] https://en.bitcoin.it/wiki/Raw_Transactions
[2] https://bitcoin.org/en/developer-examples#simple-raw-transaction

[TookDk]

but i still want to know if there is a way to send bitcoin without having to import the wallet.dat into bitcoin-qt and going online with it?

You can always import single private keys into bitcoin core by using the command importprivkey.
The private key will just be added to your current wallet.dat

[ranochigo]

can i use bitcoin core as an offline (cold) wallet?

what i want to do is, i want to install bitcoin-QT on an offline pc and just use it to create an address and send my bitcoin there.
can i do this without need of blockchain?


also what should i do (later) if someday i want to spend these bitcoins? how can i send them without having to go online and download blockchain OR exporting private keys

You can generate a wallet without internet, it is also possible to generate it without electronics. The internet is not so vulnerable such that your bitcoin would be stolen once you switch on your internet. As long as you do regular security patches, don't install anything suspicious or visit unsafe websites, you won't be hacked. I would really recommend you to use paper wallets and create new once when they are spent. Hardware failures are very possible, paper would have a longer lifespan than typical hard disk.

[TookDk]

You can generate a wallet without internet, it is also possible to generate it without electronics. The internet is not so vulnerable such that your bitcoin would be stolen once you switch on your internet. As long as you do regular security patches, don't install anything suspicious or visit unsafe websites, you won't be hacked. I would really recommend you to use paper wallets and create new once when they are spent. Hardware failures are very possible, paper would have a longer lifespan than typical hard disk.

True.

Also, you simple sleep better with paper wallets under your bed.
OP, you should try it, you will have the best sleep ever 

[pooya87]

If you want a super easy and reasonable safe setup:

Use your offline computer to generate address with a downloaded version of Ninja's page (https://www.bitaddress.org/).
Print the page as pdf including the QR code for the private address, store locally on your offline computer (or just as txt, if you don't care about the QR).
(you can encrypt the pdf files with truecrypt if you want to add encryption).

When you need to spend coins, then open the pdf file on your offline, use mycelium (or other wallet that support camera) to capture the QR direct from the screen of your offline computer.
You can just make, lets say 10-20 offline wallets, and divide your funds on these, so you don't have to redeem all at once.

With this setup will your offline computer never be connected to the internet.
You really don't need to worry about malware, as long as you make sure that computer never go online.

If you don't trust the random generator in Ninja's page just use a dice to make a 99 digit base6 random number (bitaddress.org can convert this into a bitcoin addy).

The core of this method is to use bitaddress.org offline.

thanks for putting time to explain this, but unfortunately this is not what i needed

[pooya87]

can i use bitcoin core as an offline (cold) wallet?

Yes. You dont have to sync to create private keys and corresponding addresses. The next version even allows you to create import watch only addresses.

what i want to do is, i want to install bitcoin-QT on an offline pc and just use it to create an address and send my bitcoin there.
can i do this without need of blockchain?

Yes.

also what should i do (later) if someday i want to spend these bitcoins? how can i send them without having to go online and download blockchain OR exporting private keys

You would have to create a transaction by hand[1][2]. I highly suggest you try to create a raw transaction on the testnet before you try this with your actual coins. Bitcoin core/qt 0.10.0 will have an option to add "watch only" addresses, which will probably enable you to use listunspent on the online wallet. Besides that, if you understand how createrawtransaction work you can use any block explorer to get the information you need to create a transaction. Write the data by hand into your offline wallet and copy the signed transaction via a text file or by hand to your online wallet for broadcasting. The wallet does not have to be fully synced to broadcast a transaction AFAIK.

As others have pointed out, there are other wallets that are easier to use as an offline/online combi wallet.


[1] https://en.bitcoin.it/wiki/Raw_Transactions
[2] https://bitcoin.org/en/developer-examples#simple-raw-transaction

thanks man, that is exactly what i needed. i didn't know the term "raw transaction" by reading it i now know what to do. also there was a good example at the bottom of the page. now i have to do some test runs

[shorena]

-snip-
thanks man, that is exactly what i needed. i didn't know the term "raw transaction" by reading it i now know what to do. also there was a good example at the bottom of the page. now i have to do some test runs

Yep, run some tests first to be familiar with it. I did a few on testnet before I made my first raw tx on the main net, but as in the example regtest should be faster as you dont have to sync the testnet. Also keep in mind that there are no checks when you create a rawtransaction, the wallet will just do it, even if your inputs do not exists.