It is the same data folder as the non-QT version of the standard client used to use:
(This defaults to C:\Documents and Settings\YourUserName\Application data\Bitcoin on Windows XP and to C:\Users\YourUserName\Appdata\Roaming\Bitcoin on Windows Vista, 7, 8, and ...
To export a private key from your Satoshi bitcoin-qt client:
launch your bitcoin client as usual and wait for it to load the blockchain and start up
click on 'help' in the menu bar (top right)
click on 'debug window'
select the 'console' tab
type: walletpassphrase "your walletpassphrase here" 600
type: dumpprivkey [your Bitcoin address here]
this will ...
Select Help (to the right of Settings)
Select Debug Window
If you encrypted your wallet, unlock it by entering walletpassphrase "YourLongPassphrase" 600 next to the > input box
Next to the > input box type importprivkey <bitcoinprivkey> (Note that the private key must not have spaces, remove them if they are included in ...
First, close the Bitcoin-Qt client.
Then you have to locate your Bitcoin folder. For Windows, it should be here:
In that folder, there should be a wallet.dat file.
If you currently have no bitcoins in your wallet, you can just delete that file and replace it with your backup.
If you have some bitcoins in this wallet as well, backup ...
There are two different encodings used.
Everything in the Bitcoin protocol, including transaction signatures and alert signatures, uses DER encoding. This results in 71 bytes signatures (on average), as there are several header bytes, and the R and S valued are variable length.
For message signatures, a custom encoding is used which is more compact (and ...
wipes the chainstate (the UTXO set)
wipes the block index (the database with information about which block is where on disk)
rebuilds the block index (by going over all blk*.dat files, and finding things in it that look like blocks)
rebuilds the chainstate (redoing all validation for blocks) based on the blocks now in the index
You need to put the old wallet.dat in your bitcoin data directory.
The default for Windows is:
C:\Documents and Settings\YourUserName\Application data\Bitcoin (XP)
C:\Users\YourUserName\Appdata\Roaming\Bitcoin (Vista and 7)
Then run the bitcoin client with the -rescan option.
Alternatively you can run the bitcoin client with the -datadir=<location of ...
The signing mechanism is a way of proving that a particular message was signed by the holder of an address' private key. A merchant could ask that you sign a message stating where you want your order shipped to, using one of the addresses your payment originated from.
You should sign a statement saying "I, Jane Doe (firstname.lastname@example.org) sent 1.23 BTC to ...
Since bitcoind/Bitcoin-qt 0.8, no transaction index is kept anymore by default, as it is not necessary for validation in the new database model.
Instead, there is only a database of unspent transaction outputs, which has enough information to (slowly) locate transactions in block files. getrawtransaction uses this, but it only works for transactions that ...
The backup file is encrypted using your chosen password. You can use OpenSSL to decrypt:
openssl enc -d -aes-256-cbc -a -in <filename>
The two pieces of software, Bitcoin Core and Bitcoin-XT, are very similar. Bitcoin-XT is actually just a fork of Bitcoin Core with some features added that Bitcoin Core developers didn't deem appropriate, such as a larger block size (BIP 101) and relaying of double spends.
Bitcoin Core is more up-to-date with all of the work that the community doing. ...
Bitcoin Core does have mining components in it. In fact most available mining software actually rely on Core (or something abstracting Core's services) in order to get the block built before it attempts to mine it. Bitcoin Core has the capability to serve the information to other software so that they can mine blocks. Furthermore, Bitcoin Core does have the ...
The Bitcoin Improvement Proposal that defines the Bitcoin URI scheme is BIP21.
The simple syntax is:
On the desktop all of Armory, Electrum and MultiBit respond to Bitcoin URI clicks in a browser and I believe Bitcoin-QT V0.7 does as well.
On mobiles Android ...
Enable txindex=1 in your bitcoin.conf (You'll need to rebuild the database as the transaction index is normally not maintained, start using -reindex to do so), and use the getrawtransaction call to request information about any transaction (it won't work for the genesis block's coinbase transaction though, it's a special case).
Note that this will only give ...
"TL;DR: Bitcoin mining is virtually immune to someone attacking it with a supercomputer, because the mining market is already flooded with supercomputers custom tailored to the job at the hardware level."
(via Cort Ammon in comments)
First of all, the difficulty reset happens after 2016 blocks. That's only after about 14 days if the hashrate is stable. When ...
If the only library is closed source, then there's a project to make
an open source one.
If the only library is GPL, then there's a project to make a non-GPL
If the best library is MIT, Boost, new-BSD or public domain, then we
can stop re-writing it.
I don't question that GPL is a good license for operating systems,
Suppose Alice wants to add a fake transaction where she receives X ammount of BTC. I understand that in order to add that transaction to the blockchain she would have to compete against all the other miners to generate the next block, which makes it improbable to happen as an individual against them.
No, that isn't correct. No matter how much mining power ...
Copy your public receiving addresses from Bitcoin-Qt.
Go to the Bitcoin-Qt console: click Help/Debug Window and then select the Console tab.
Run walletpassphrase [your password] [timeout in seconds] to unlock your password protected wallet.
Run dumpprivkey [Receiving Bitcoin Address] for each receiving address to be migrated to MultiBit. There ...
You can either run bitcoin-qt or bitcoind, not both at the same time (the Qt part is not just a frontend on top of the RPC code, it uses the core directly).
You can however run Bitcoin-Qt with the -server command-line switch, in which case it will also expose an RPC service (essentially functioning like bitcoind in addition to the GUI interface). The RPC ...
ZeroMQ is a publisher / subscriber messaging system. In the case of Bitcoin Core it is a socket which other applications can connect to and get notifications of new events in real time, without having to repeatedly ask the daemon if there are any new events. ZMQ support is useful for any systems interfacing with the network like miners and wallets, which can ...
Miners have started signalling for BIP 91, which sets bit 4 in version numbers. When BIP 91 activates, it will force miners to set bit 1 (which then indirectly will cause activation of BIP 141 SegWit).
No software release has implemented BIP 91, as a result, it warns because it sees an unknown feature rollout with significant support from miners.
The bitcoin client stores, in the wallet, the transactions that affect coins it manages. If it sees a new transaction, it checks to see if that transaction affects any accounts stored in the wallet. If so, the wallet is updated. Similarly, if the chain is reorganized, the wallet is updated.
However, the client doesn't check to make sure the wallet is ...
If you want, you can pay $100 for the standard, ANSI X9.62. Or, you can cheat and look at RFC3278, section 8.2. It is in DER format consisting of a SEQUENCE of two INTEGERs. The first INTEGER is r, the second s.
If you look at this transaction you can see that one of the signatures is:
The Bitcoin client has been hosted on GitHub for a while now. It's very close to what Satoshi initially wrote. Here's the first commit dated back to 2009: https://github.com/bitcoin/bitcoin/tree/4405b78d6059e536c36974088a8ed4d9f0f29898
You could also browse all the commits from way back: https://github.com/bitcoin/bitcoin/commits/master?page=151
Some other ...
P2PKH: "Pay To Public Key Hash"
This is how transactions are made. You are requiring the sender to supply a valid signature (from the private key) and public key. The transaction output script will use the signature and public key and through some cryptographic functions will check if it matches with the public key hash, if it does, then the funds will be ...
You can start it from the command-line using:
open Bitcoin-Qt.app --args -server
I think the --args option to open is OSX 10.6 and later; if you are running an older OSX put server=1 in your ~/Library/Application Support/Bitcoin/bitcoin.conf file. In fact, to use the -server command you must set a -rpcuser/-rpcpassword, so I'd suggest creating a bitcoin....
Since Bitcoin-Core 0.11.0 you can prune (trim) the blockchain in Bitcoin-Qt.
But not from the UI.
You need to add prune=550 to your bitcoin.conf file and restart Bitcoin-Qt.
-prune=<target in MiB> will tell bitcoin-core to remove blocks which are older than oldest block that can be kept with a chainsize (sum of block-sizes) of <target&...
This is not a thorough schooling on Tor and only shows how to configure it to work together with Bitcoin Core.
Bitcoin Core includes Tor integration
When Tor is correctly setup on your system, Bitcoin Core automatically identifies Tor and creates an anonymous service. Little configuration is required to be 'off the grid' and, just a tiny bit more to be ...
Use the -datadir option.
Right-click on your bitcoin-qt shortcut, press properties, and add -datadir=D:\Bitcoin
Go make that directory, then run bitcoin. If a bunch of files show up in there, you've done it correctly.
File > Backup Wallet