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Questions tagged [bitcoin-core]

This tag should be used for questions pertaining to Bitcoin Core. Bitcoin Core is an MIT-licensed Qt 5 GUI application for the original Bitcoin codebase. Additional/previous names include "Bitcoin-Qt", "Satoshi-Client", and "Standard Client". This tag should be used when referring to the Bitcoin ...

36
votes
2answers
55k views

How can I export the private key for an address from the satoshi client?

If I want to transfer an address from the satoshi client into a different client, how can I find its private key to do so?
32
votes
2answers
38k views

How do I import a private key into Bitcoin-Core?

How do I import a private key into Bitcoin-Qt? bitcoind is nowhere to be found, and pywallet says it requires "bsddb" when I run it, which is also nowhere to be found. I generated some vanity ...
35
votes
4answers
52k views

Where is the data folder for Bitcoin-Qt?

Where can I find the blockchain, wallet.dat, etc. on each of the operating systems Bitcoin-Qt supports?
20
votes
5answers
33k views

Bitcoin-Qt setup: Change block-chain file location, settings? documentation?

I am installing Bitcoin-Qt and have been reading about Bitcoin basics, but I found very little information on the client. I have a few questions about the Bitcoin-Qt program (v0.8.1-beta under Windows ...
15
votes
3answers
9k views

Are there Bitcoin password crackers I can use to recover forgotten passwords?

I've lost the password to one of my wallets (it's a small one, don't worry). I was sure I remembered the password ... but evidently I don't. Is there a program that I can use to brute-force my ...
10
votes
1answer
3k views

How can I setup Bitcoin to be anonymous with Tor?

Bitcoin is billed as many things, among them its anonymity is highly regarded. While it is true that a transaction does not identify a user or wallet, recent news shows that there is the potential for ...
41
votes
3answers
141k views

Import wallet.dat into a new Bitcoin-Qt client

I had Bitcoin-Qt on my computer with several bitcoins in my wallet, using Vista. Then my computer crashed. Finally I was able to get my computer fixed and download a new version of Bitcoin-Qt. Now I ...
31
votes
4answers
10k views

Why can’t the genesis block coinbase be spent?

According to the bitcoin wiki: The first 50BTC block reward went to address 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa, though this reward can't be spent due to a quirk in the way that the genesis block is ...
4
votes
4answers
7k views

What can I do when the blockchain synchronization is stuck at a specific block?

I hadn't started/used my Bitcoin client for ages. Now, whenever I start the client, it is downloading block 135407 and does not progress past it. What can I do?
7
votes
2answers
2k views

Sync with bitcoin-qt very slow (0,01%)

i have an issue that the synchronisation is very slow. i am 14 weeks behind and it takes 12 weeks to get it synced regarding the client. rate is only 0,01%. I have a fast broadband and no other ...
32
votes
1answer
51k views

How can I restore my wallet?

I just purchased a new laptop and I want to decommission my old one. I have a back-up of my wallet.dat file copied to my new PC. What do I need to do to restore it to my Bitcoin (Windows) client? ...
23
votes
4answers
34k views

How do I import private keys from Bitcoin-qt to Multibit client?

Question says it. I spent 20 mins Googling. Saw several links on bitcointalk.com but amazingly found no solution to this. Am I the first one trying to do this? Note the following are not the ...
15
votes
1answer
17k views

How does “Sign Message” work?

How does "Sign Message" option in the Bitcoin QT client work? I can't find any description or documentation of it. Do I have to use this option to sign some message when I receive bitcoins? If so, ...
16
votes
1answer
7k views

Why the signature is always 65 (1+32+32) bytes long?

A signature created by the Bitcoin-Qt client can always be decoded (base64) to a 65-byte array. This array seems (according to https://github.com/bitcoin/bitcoin/blob/master/src/key.cpp#L217) to ...
5
votes
2answers
626 views

HTLC (Hash Time Lock Contract) using bitcoin-qt

Is it possible to manually create a HTLC using the bitcoin-qt command line? I know how to manually creating createrawtransaction/sendrawtransaction using the bitcoin-qt clients command line, and ...
27
votes
2answers
11k views

How can I combine all the tiny amounts I've received to minimise transaction fees, and do I need to?

Important parts in bold, for those who don't want to read the detail! I've received lots of tiny transactions, in amounts sometimes as low as 0.000003BTC. Even though I've also received (relatively) ...
13
votes
3answers
7k views

What is the exact formula for calculating transaction fees?

According to the Wiki: If the blocksize is more than 250 kB, transactions get increasingly more expensive as the blocksize approaches the limit of 500 kB. Sending a transaction when the blocksize ...
13
votes
3answers
4k views

Can Bitcoin-Qt be configured to trim the blockchain?

I run Bitcoin-Qt and Bitcoin Armory on a laptop. I don't have the space to store the whole 20 GB (or however big it is now) blockchain. I understand the need to run through the entire thing for ...
10
votes
1answer
10k views

How to transfer only the blockchain to a friend's computer?

After installing the bitcoin client (Qt) a friend got interested as well. He doesn't have as fast an internet connection, though, so I thought of burning some DVDs with the blockchains for him to have....
23
votes
2answers
21k views

How exactly does -rescan work?

-rescan is a command line argument that is passed to the bitcoin client after restoring wallet.dat from backup. Which files get recalculated? Which files does the rescan command read? Why is it a ...
9
votes
2answers
3k views

Is there a way to change the wallet.dat location without changing the entire data directory?

I know that Bitcoin supports the -datadir command line option which specifies that the wallet.dat and blockchain should be stored in a custom location rather than %appdata%\roaming\bitcoin but is ...
5
votes
5answers
20k views

My client stopped synchronizing, how can I access my wallet?

My wallet has been stuck synchronizing for 21 days, my transfer is in the block chain but I can't get it to sync with my wallet. I've closed firewalls, uninstalled and reinstalled QT with back up and ...
3
votes
2answers
1k views

How to get a history of incoming and outgoing transactions for a certain address?

Along with the history of incoming and outgoing transactions, how would I find the first block that that address appeared in (to find when the wallet was created)? I want to do this by parsing with ...
10
votes
1answer
2k views

Is there developer documentation for the Bitcoin Core source code?

Is there a documentation somewhere to understand the C++ code of Bitcoin Core (available on Github) "from a to z" and being able to recreate it ?
18
votes
1answer
11k views

Get non-wallet transactions using bitcoin rpc (gettransaction)

I am playing around with Bitcoin-qt. I want to iterate all blocks and all their transactions. So far I've been able to get a list of all tx's in the blocks I want to. Now I want to get information ...
19
votes
1answer
8k views

Bitcoin URL scheme

What is the URL scheme that is used by Bitcoin to copy transaction information directly into the client? Which versions of Bitcoin clients support it?
16
votes
2answers
9k views

What are the safety guidelines for using the Sign Message feature?

bitcoin-qt's dialog box states, "Be careful not to sign anything vague, as phishing attacks may try to trick you into signing your identity over to them. Only sign fully-detailed statements you agree ...
10
votes
3answers
34k views

How to resolve “no block source available”?

I've got some trouble using bitcoin-qt. It stays on: "No block source available... 242 weeks behind." And "Catching up ... Processed 0" etc... Map port using UPnP is activated, and proxy disabled ...
8
votes
2answers
4k views

Can wallets be shared by different machines?

I have a bitcoin client installed on machine one. Let's say it has 5 coins in there. I then have another machine, with another client on it. Can both machines see the same wallet? Do I have to have a ...
20
votes
2answers
45k views

How to use the “Bootstrap.dat” file with bitcoin-qt?

I have searched around, and nothing I find works for me. Downloaded the approx. 10 GB Bootstrap.dat file. Now stuck on trying to link it with Bitcoin-QT. Tried the following command in the console ...
16
votes
1answer
4k views

getrawtransaction error? [Code -5]

I'm trying to read raw transactions but there is a problem; Seems like getrawtransaction only works for recent transactions, old transactions give me the next error: No information available about ...
13
votes
1answer
12k views

How do I specify in which directory Bitcoin blocks and other data should be stored? [duplicate]

I am on Windows and installed the Bitcoin wallet. The block folder seems to grow bigger everyday and is stored on my C drive in the roaming directory. I would like to set this to some other folder on ...
12
votes
2answers
2k views

Estate planning: how can I ensure my bitcoins are inheritable?

What are good ways to ensure my bitcoins can be inherited by my family when I die or become permanently incapacitated? I think there are probably two significantly different situations to account for,...
15
votes
4answers
4k views

Why does the Bitcoin protocol use the little-endian notation?

Why does the Bitcoin use the litte-endian notation? It is less common than big-endian notation, thus when programming low-level applications working with Bitcoin protocol, one quite often has to ...
11
votes
2answers
1k views

How can I choose the address bitcoins are sent from?

So let's say I have multiple bitcoin addresses (some of them already received bitcoins), created a new bitcoin address, received bitcoins on it and would like to use the very same address to send them ...
7
votes
2answers
4k views

What is the minimum transaction fee used for?

I have the bitcoin-qt client running on Ubuntu 12.10 and I see a transaction fee box in the preferences, but I am unsure of what it actually means - the wiki is overly complex, and I am unable to find ...
8
votes
1answer
8k views

How do I configure Bitcoin Core to connect always to a particular node?

By reading https://bitcoin.org/en/full-node I've decided that I want to run a FULL node (let's call it 'X'), to contribute to the P2P network. So, I'll leave its ports open, or have a DMZ zone with a ...
13
votes
2answers
6k views

How can I import a private key into the Bitcoin client? [duplicate]

I have a private key and I want to add it to the keys in the Bitcoin client. Is there an easy way to do this?
12
votes
2answers
5k views

How to make Bitcoin-Qt client portable? (Windows)

It is a nice project and all, but I think in 2013 it shouldn't be a challenge to save all of an application's files into its own folder (maybe even by default), so you can use it without installing/...
11
votes
3answers
6k views

Bitcoin client won't connect to the network

I installed Bitcoin QT yesterday and it was very slow to connect to the network. It didn't actually get there for over an hour. Today I opened it again and it won't connect to the network at all. Any ...
8
votes
1answer
11k views

How do you apply “-zapwallettxes” on Windows?

On May 27 I tried to sell some Bitcoins(for the first time). Since that day the transaction is in the status "unconfirmed". The amount is booked from my wallet, but isn't booked to my bank account. ...
6
votes
2answers
3k views

Why does the initial blockchain download get stuck part way through?

I am trying to get Bitcoin up and running on a fairly underpowered laptop and Windows Vista using Bitcoin-Qt 0.5.0.1. After installing and starting the program, I am stuck at at the syncing stage at ...
4
votes
2answers
587 views

Does the satoshi client always send the change of a transaction to a newely generated address?

Experimentally, this seems to be the case, but is it always like this or depends on some details? Also, does it generate a new address each time this is done, or first searches the wallet if there is ...
3
votes
3answers
1k views

Can I sell my BTC and still claim my BCH?

I held a small amount of BTC back in August (had them since 2014) but now wish to sell them. Do I need to claim my BCH before selling my BTC or am I correct in thinking that the two completely ...
3
votes
1answer
2k views

Since which version the mining functionality removed from wallet?

As I'm starting to learn to create a new altcoin, I found there is a remarkable difference between old and new Bitcoin/Litecoin Core wallet is that old versions (0.6.9 of Litecoin) have mining ...
1
vote
1answer
432 views

Bitcoin Mining as a Newbie (link wallet to another person's miner)

I'm new in bitcoin mining. I would wish to mining to make some profit. I have just talked to someone and he has told me I can partner with him to use his miner. I have some bitcoins ready with me and ...
1
vote
1answer
2k views

how to install Bitcoin and bitcoin cash on the same ubuntu server?

I've installed bitcoin core as the documentation in bitcoin.org and its working great. then, I tried to install bitcoin-ABC manually as following: wget bitcoin-cash-gnu.tar.gz tar xzf bitcoin-cash-...
14
votes
2answers
5k views

When should I use -reindex-chainstate and when -reindex

What is the difference between the options -reindex and -reindex-chianstate? Is one of the options faster? When should each option be used?
14
votes
2answers
10k views

ECDSA r, s encoding as a signature

An ECDSA algorithm when signing a given messages produces a pair of outputs, r and s. How, given a sigStr from a Tx can one extract r and s? Are they just concatenated byte arrays of a specific length,...
24
votes
2answers
11k views

Bitcoin-Qt command line control on Mac

I'm trying to communicate with the new Bitcoin-Qt -server via a command line on Mac. I run ./Bitcoin-Qt -server, the application starts, but my terminal window is stuck on an empty line (no matter ...